Attribute.GetCustomAttribute 方法
重要
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检索应用于程序集、模块、类型成员或方法参数的指定类型的自定义属性。
| GetCustomAttribute(ParameterInfo, Type, Boolean) |
检索应用于方法参数的自定义属性。 参数指定方法参数、要搜索的自定义属性的类型以及是否搜索方法参数的祖先。 |
| GetCustomAttribute(MemberInfo, Type, Boolean) |
检索应用于类型成员的自定义属性。 参数指定成员、要搜索的自定义属性的类型以及是否搜索成员的祖先。 |
| GetCustomAttribute(Assembly, Type, Boolean) |
检索应用于程序集的自定义属性。 参数指定程序集、要搜索的自定义属性的类型以及忽略的搜索选项。 |
| GetCustomAttribute(Module, Type, Boolean) |
检索应用于模块的自定义属性。 参数指定模块、要搜索的自定义属性的类型以及忽略的搜索选项。 |
| GetCustomAttribute(Module, Type) |
检索应用于模块的自定义属性。 参数指定模块和要搜索的自定义属性的类型。 |
| GetCustomAttribute(MemberInfo, Type) |
检索应用于类型成员的自定义属性。 参数指定成员和要搜索的自定义属性的类型。 |
| GetCustomAttribute(Assembly, Type) |
检索应用于指定程序集的自定义属性。 参数指定程序集和要搜索的自定义属性的类型。 |
| GetCustomAttribute(ParameterInfo, Type) |
检索应用于方法参数的自定义属性。 参数指定方法参数和要搜索的自定义属性的类型。 |
GetCustomAttribute(ParameterInfo, Type, Boolean)
检索应用于方法参数的自定义属性。 参数指定方法参数、要搜索的自定义属性的类型以及是否搜索方法参数的祖先。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::ParameterInfo ^ element, Type ^ attributeType, bool inherit);C#
public static Attribute? GetCustomAttribute (System.Reflection.ParameterInfo element, Type attributeType, bool inherit);C#
public static Attribute GetCustomAttribute (System.Reflection.ParameterInfo element, Type attributeType, bool inherit);static member GetCustomAttribute : System.Reflection.ParameterInfo * Type * bool -> AttributePublic Shared Function GetCustomAttribute (element As ParameterInfo, attributeType As Type, inherit As Boolean) As Attribute参数
- element
- ParameterInfo
一个从 ParameterInfo 类派生的对象，该类描述类成员的参数。
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
- inherit
- Boolean
如果为 true，则指定还在 element 的祖先中搜索自定义属性。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
找到多个请求的属性。
无法加载自定义属性类型。
示例
下面的代码示例定义自定义参数 Attribute 类，并将自定义属性应用于派生类和派生类的基的方法。 该示例演示如何使用 GetCustomAttribute 该方法返回属性。
// Example for the Attribute::GetCustomAttribute( ParameterInfo*, Type*, bool )
// method.
using namespace System;
using namespace System::Collections;
using namespace System::Reflection;
namespace NDP_UE_CPP
{
// Define a custom parameter attribute that takes a single message argument.
[AttributeUsage(AttributeTargets::Parameter)]
public ref class ArgumentUsageAttribute: public Attribute
{
protected:
// usageMsg is storage for the attribute message.
String^ usageMsg;
public:
// This is the attribute constructor.
ArgumentUsageAttribute( String^ UsageMsg )
{
this->usageMsg = UsageMsg;
}
property String^ Message
{
// This is the Message property for the attribute.
String^ get()
{
return usageMsg;
}
void set( String^ value )
{
this->usageMsg = value;
}
}
};
public ref class BaseClass
{
public:
// Assign an ArgumentUsage attribute to the strArray parameter.
// Assign a ParamArray attribute to strList.
virtual void TestMethod( [ArgumentUsage("Must pass an array here.")]array<String^>^strArray,
...array<String^>^strList ){}
};
public ref class DerivedClass: public BaseClass
{
public:
// Assign an ArgumentUsage attributes to the strList parameter.
virtual void TestMethod( array<String^>^strArray, [ArgumentUsage(
"Can pass a parameter list or array here.")]array<String^>^strList ) override {}
};
void DisplayParameterAttributes( MethodInfo^ mInfo, array<ParameterInfo^>^pInfoArray, bool includeInherited )
{
Console::WriteLine( "\nParameter attribute information for method \"{0}"
"\"\nincludes inheritance from base class: {1}.", mInfo->Name, includeInherited ? (String^)"Yes" : "No" );
// This implements foreach( ParameterInfo* paramInfo in pInfoArray ).
IEnumerator^ myEnum = pInfoArray->GetEnumerator();
while ( myEnum->MoveNext() )
{
ParameterInfo^ paramInfo = safe_cast<ParameterInfo^>(myEnum->Current);
// See if the ParamArray attribute is defined.
bool isDef = Attribute::IsDefined( paramInfo, ParamArrayAttribute::typeid );
if ( isDef )
Console::WriteLine( "\n The ParamArray attribute is defined "
"for \n parameter {0} of method {1}.", paramInfo->Name, mInfo->Name );
// See if ParamUsageAttribute is defined.
// If so, display a message.
ArgumentUsageAttribute^ usageAttr = static_cast<ArgumentUsageAttribute^>(Attribute::GetCustomAttribute( paramInfo, ArgumentUsageAttribute::typeid, includeInherited ));
if ( usageAttr != nullptr )
{
Console::WriteLine( "\n The ArgumentUsage attribute is defined "
"for \n parameter {0} of method {1}.", paramInfo->Name, mInfo->Name );
Console::WriteLine( "\n The usage "
"message for {0} is:\n \"{1}\".", paramInfo->Name, usageAttr->Message );
}
}
}
}
int main()
{
Console::WriteLine( "This example of Attribute::GetCustomAttribute( ParameterInfo*, "
"Type*, bool )\ngenerates the following output." );
// Get the class type, and then get the MethodInfo object
// for TestMethod to access its metadata.
Type^ clsType = NDP_UE_CPP::DerivedClass::typeid;
MethodInfo^ mInfo = clsType->GetMethod( "TestMethod" );
// Iterate through the ParameterInfo array for the method parameters.
array<ParameterInfo^>^pInfoArray = mInfo->GetParameters();
if ( pInfoArray != nullptr )
{
NDP_UE_CPP::DisplayParameterAttributes( mInfo, pInfoArray, false );
NDP_UE_CPP::DisplayParameterAttributes( mInfo, pInfoArray, true );
}
else
Console::WriteLine( "The parameters information could "
"not be retrieved for method {0}.", mInfo->Name );
}
/*
This example of Attribute::GetCustomAttribute( ParameterInfo*, Type*, bool )
generates the following output.
Parameter attribute information for method "TestMethod"
includes inheritance from base class: No.
The ParamArray attribute is defined for
parameter strList of method TestMethod.
The ArgumentUsage attribute is defined for
parameter strList of method TestMethod.
The usage message for strList is:
"Can pass a parameter list or array here.".
Parameter attribute information for method "TestMethod"
includes inheritance from base class: Yes.
The ArgumentUsage attribute is defined for
parameter strArray of method TestMethod.
The usage message for strArray is:
"Must pass an array here.".
The ParamArray attribute is defined for
parameter strList of method TestMethod.
The ArgumentUsage attribute is defined for
parameter strList of method TestMethod.
The usage message for strList is:
"Can pass a parameter list or array here.".
*/
C#
// Example for the Attribute.GetCustomAttribute( ParameterInfo, Type, Boolean )
// method.
using System;
using System.Reflection;
namespace NDP_UE_CS
{
// Define a custom parameter attribute that takes a single message argument.
[AttributeUsage( AttributeTargets.Parameter )]
public class ArgumentUsageAttribute : Attribute
{
// This is the attribute constructor.
public ArgumentUsageAttribute( string UsageMsg )
{
this.usageMsg = UsageMsg;
}
// usageMsg is storage for the attribute message.
protected string usageMsg;
// This is the Message property for the attribute.
public string Message
{
get { return usageMsg; }
set { usageMsg = value; }
}
}
public class BaseClass
{
// Assign an ArgumentUsage attribute to the strArray parameter.
// Assign a ParamArray attribute to strList using the params keyword.
public virtual void TestMethod(
[ArgumentUsage("Must pass an array here.")]
String[] strArray,
params String[] strList)
{ }
}
public class DerivedClass : BaseClass
{
// Assign an ArgumentUsage attribute to the strList parameter.
// Assign a ParamArray attribute to strList using the params keyword.
public override void TestMethod(
String[] strArray,
[ArgumentUsage("Can pass a parameter list or array here.")]
params String[] strList)
{ }
}
class CustomParamDemo
{
static void Main( )
{
Console.WriteLine(
"This example of Attribute.GetCustomAttribute( Parameter" +
"Info, Type, Boolean )\ngenerates the following output." );
// Get the class type, and then get the MethodInfo object
// for TestMethod to access its metadata.
Type clsType = typeof(DerivedClass);
MethodInfo mInfo = clsType.GetMethod("TestMethod");
// Iterate through the ParameterInfo array for the method parameters.
ParameterInfo[] pInfoArray = mInfo.GetParameters();
if (pInfoArray != null)
{
DisplayParameterAttributes( mInfo, pInfoArray, false );
DisplayParameterAttributes( mInfo, pInfoArray, true );
}
else
Console.WriteLine("The parameters information could " +
"not be retrieved for method {0}.", mInfo.Name);
}
static void DisplayParameterAttributes( MethodInfo mInfo,
ParameterInfo[] pInfoArray, bool includeInherited )
{
Console.WriteLine(
"\nParameter attribute information for method \"" +
"{0}\"\nincludes inheritance from base class: {1}.",
mInfo.Name, includeInherited ? "Yes" : "No" );
// Display the attribute information for the parameters.
foreach( ParameterInfo paramInfo in pInfoArray )
{
// See if the ParamArray attribute is defined.
bool isDef = Attribute.IsDefined( paramInfo,
typeof(ParamArrayAttribute));
if( isDef )
Console.WriteLine(
"\n The ParamArray attribute is defined " +
"for \n parameter {0} of method {1}.",
paramInfo.Name, mInfo.Name);
// See if ParamUsageAttribute is defined.
// If so, display a message.
ArgumentUsageAttribute usageAttr = (ArgumentUsageAttribute)
Attribute.GetCustomAttribute( paramInfo,
typeof(ArgumentUsageAttribute),
includeInherited );
if( usageAttr != null )
{
Console.WriteLine(
"\n The ArgumentUsage attribute is def" +
"ined for \n parameter {0} of method {1}.",
paramInfo.Name, mInfo.Name );
Console.WriteLine( "\n The usage " +
"message for {0} is:\n \"{1}\".",
paramInfo.Name, usageAttr.Message);
}
}
}
}
}
/*
This example of Attribute.GetCustomAttribute( ParameterInfo, Type, Boolean )
generates the following output.
Parameter attribute information for method "TestMethod"
includes inheritance from base class: No.
The ParamArray attribute is defined for
parameter strList of method TestMethod.
The ArgumentUsage attribute is defined for
parameter strList of method TestMethod.
The usage message for strList is:
"Can pass a parameter list or array here.".
Parameter attribute information for method "TestMethod"
includes inheritance from base class: Yes.
The ArgumentUsage attribute is defined for
parameter strArray of method TestMethod.
The usage message for strArray is:
"Must pass an array here.".
The ParamArray attribute is defined for
parameter strList of method TestMethod.
The ArgumentUsage attribute is defined for
parameter strList of method TestMethod.
The usage message for strList is:
"Can pass a parameter list or array here.".
*/
open System
open System.Reflection
// Define a custom parameter attribute that takes a single message argument.
[<AttributeUsage(AttributeTargets.Parameter); AllowNullLiteral>]
type ArgumentUsageAttribute(usageMsg) =
inherit Attribute()
// This is the Message property for the attribute.
member val Message: string = usageMsg
type BaseClass() =
// Assign an ArgumentUsage attribute to the strArray parameter.
// Assign a ParamArray attribute to strList.
abstract member TestMethod: string [] * string[] -> unit
default _.TestMethod(
[<ArgumentUsage "Must pass an array here.">]
strArray,
[<ParamArray>]
strList) = ()
type DerivedClass() =
inherit BaseClass()
// Assign an ArgumentUsage attribute to the strList parameter.
// Assign a ParamArray attribute to strList.
override _.TestMethod(
strArray,
[<ArgumentUsage "Can pass a parameter list or array here."; ParamArray>]
strList) = ()
let displayParameterAttributes (mInfo: MethodInfo) (pInfoArray: ParameterInfo []) includeInherited =
printfn $"""
Parameter attribute information for method "{mInfo.Name}"
includes inheritance from base class: {if includeInherited then "Yes" else "No"}."""
// Display the attribute information for the parameters.
for paramInfo in pInfoArray do
// See if the ParamArray attribute is defined.
let isDef = Attribute.IsDefined(paramInfo, typeof<ParamArrayAttribute>)
if isDef then
printfn $"\n The ParamArray attribute is defined for \n parameter {paramInfo.Name} of method {mInfo.Name}."
// See if ParamUsageAttribute is defined.
// If so, display a message.
let usageAttr =
Attribute.GetCustomAttribute(paramInfo, typeof<ArgumentUsageAttribute>, includeInherited)
:?> ArgumentUsageAttribute
if usageAttr <> null then
printfn $"\n The ArgumentUsage attribute is defined for \n parameter {paramInfo.Name} of method {mInfo.Name}."
printfn $"\n The usage message for {paramInfo.Name} is:\n \"{usageAttr.Message}\"."
printfn "This example of Attribute.GetCustomAttribute(ParameterInfo, Type, Boolean)\ngenerates the following output."
// Get the class type, and then get the MethodInfo object
// for TestMethod to access its metadata.
let clsType = typeof<DerivedClass>
let mInfo = clsType.GetMethod "TestMethod"
// Iterate through the ParameterInfo array for the method parameters.
let pInfoArray = mInfo.GetParameters()
if pInfoArray <> null then
displayParameterAttributes mInfo pInfoArray false
displayParameterAttributes mInfo pInfoArray true
else
printfn $"The parameters information could not be retrieved for method {mInfo.Name}."
// This example of Attribute.GetCustomAttribute( ParameterInfo, Type, Boolean )
// generates the following output.
//
// Parameter attribute information for method "TestMethod"
// includes inheritance from base class: No.
//
// The ParamArray attribute is defined for
// parameter strList of method TestMethod.
//
// The ArgumentUsage attribute is defined for
// parameter strList of method TestMethod.
//
// The usage message for strList is:
// "Can pass a parameter list or array here.".
//
// Parameter attribute information for method "TestMethod"
// includes inheritance from base class: Yes.
//
// The ArgumentUsage attribute is defined for
// parameter strArray of method TestMethod.
//
// The usage message for strArray is:
// "Must pass an array here.".
//
// The ParamArray attribute is defined for
// parameter strList of method TestMethod.
//
// The ArgumentUsage attribute is defined for
// parameter strList of method TestMethod.
//
// The usage message for strList is:
// "Can pass a parameter list or array here.".
' Example for the Attribute.GetCustomAttribute( ParameterInfo, Type, Boolean )
' method.
Imports System.Reflection
Namespace NDP_UE_VB
' Define a custom parameter attribute that takes a single message argument.
<AttributeUsage(AttributeTargets.Parameter)> _
Public Class ArgumentUsageAttribute
Inherits Attribute
' This is the attribute constructor.
Public Sub New(UsageMsg As String)
Me.usageMsg = UsageMsg
End Sub
' usageMsg is storage for the attribute message.
Protected usageMsg As String
' This is the Message property for the attribute.
Public Property Message() As String
Get
Return usageMsg
End Get
Set
usageMsg = value
End Set
End Property
End Class
Public Class BaseClass
' Assign an ArgumentUsage attribute to the strArray parameter.
' Assign a ParamArray attribute to the strList parameter.
Public Overridable Sub TestMethod( _
<ArgumentUsage("Must pass an array here.")> _
strArray() As String, _
ParamArray strList() As String)
End Sub
End Class
Public Class DerivedClass
Inherits BaseClass
' Assign an ArgumentUsage attribute to the strList parameter.
' Assign a ParamArray attribute to the strList parameter.
Public Overrides Sub TestMethod( _
strArray() As String, _
<ArgumentUsage("Can pass a parameter list or array here.")> _
ParamArray strList() As String)
End Sub
End Class
Class DemoClass
Shared Sub DisplayParameterAttributes(mInfo As MethodInfo, _
pInfoArray() As ParameterInfo, includeInherited As Boolean)
Console.WriteLine( vbCrLf & _
"Parameter attribute information for method ""{0}""" & _
vbCrLf & "includes inheritance from the base class: {1}.", _
mInfo.Name, IIf(includeInherited, "Yes", "No"))
' Display attribute information for the parameters.
Dim paramInfo As ParameterInfo
For Each paramInfo In pInfoArray
' See if the ParamArray attribute is defined.
Dim isDef As Boolean = _
Attribute.IsDefined(paramInfo, GetType(ParamArrayAttribute))
If isDef Then
Console.WriteLine( vbCrLf & " The " & _
"ParamArray attribute is defined for " & _
vbCrLf & " parameter {0} of method {1}.", _
paramInfo.Name, mInfo.Name)
End If
' See if ParamUsageAttribute is defined.
' If so, display a message.
Dim usageAttr As ArgumentUsageAttribute = _
Attribute.GetCustomAttribute(paramInfo, _
GetType(ArgumentUsageAttribute), _
includeInherited)
If Not (usageAttr Is Nothing) Then
Console.WriteLine( vbCrLf & " The " & _
"ArgumentUsage attribute is defined for " & _
vbCrLf & " parameter {0} of method {1}.", _
paramInfo.Name, mInfo.Name)
Console.WriteLine( vbCrLf & _
" The usage message for {0} is: " & _
vbCrLf & " ""{1}"".", _
paramInfo.Name, usageAttr.Message)
End If
Next paramInfo
End Sub
Public Shared Sub Main()
Console.WriteLine( _
"This example of Attribute.GetCustomAttribute" & _
"( ParameterInfo, Type, Boolean )" & vbCrLf & _
"generates the following output." )
' Get the class type, and then get the MethodInfo object
' for TestMethod to access its metadata.
Dim clsType As Type = GetType(DerivedClass)
Dim mInfo As MethodInfo = clsType.GetMethod("TestMethod")
' Iterate through the ParameterInfo array for the method parameters.
Dim pInfoArray As ParameterInfo() = mInfo.GetParameters()
If Not (pInfoArray Is Nothing) Then
DisplayParameterAttributes(mInfo, pInfoArray, False)
DisplayParameterAttributes(mInfo, pInfoArray, True)
Else
Console.WriteLine( _
"The parameters information could " & _
"not be retrieved for method {0}.", mInfo.Name)
End If
End Sub
End Class
End Namespace ' NDP_UE_VB
' This example of Attribute.GetCustomAttribute( ParameterInfo, Type, Boolean )
' generates the following output.
'
' Parameter attribute information for method "TestMethod"
' includes inheritance from the base class: No.
'
' The ParamArray attribute is defined for
' parameter strList of method TestMethod.
'
' The ArgumentUsage attribute is defined for
' parameter strList of method TestMethod.
'
' The usage message for strList is:
' "Can pass a parameter list or array here.".
'
' Parameter attribute information for method "TestMethod"
' includes inheritance from the base class: Yes.
'
' The ArgumentUsage attribute is defined for
' parameter strArray of method TestMethod.
'
' The usage message for strArray is:
' "Must pass an array here.".
'
' The ParamArray attribute is defined for
' parameter strList of method TestMethod.
'
' The ArgumentUsage attribute is defined for
' parameter strList of method TestMethod.
'
' The usage message for strList is:
' "Can pass a parameter list or array here.".
注解
如果 element 表示派生类型的方法中的参数，则返回值包括应用于重写基方法中相同参数的可继承自定义属性。
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |
GetCustomAttribute(MemberInfo, Type, Boolean)
检索应用于类型成员的自定义属性。 参数指定成员、要搜索的自定义属性的类型以及是否搜索成员的祖先。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::MemberInfo ^ element, Type ^ attributeType, bool inherit);C#
public static Attribute? GetCustomAttribute (System.Reflection.MemberInfo element, Type attributeType, bool inherit);C#
public static Attribute GetCustomAttribute (System.Reflection.MemberInfo element, Type attributeType, bool inherit);static member GetCustomAttribute : System.Reflection.MemberInfo * Type * bool -> AttributePublic Shared Function GetCustomAttribute (element As MemberInfo, attributeType As Type, inherit As Boolean) As Attribute参数
- element
- MemberInfo
一个从 MemberInfo 类派生的对象，该类描述类的构造函数、事件、字段、方法或属性成员。
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
- inherit
- Boolean
如果为 true，则指定还在 element 的祖先中搜索自定义属性。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
element 不是构造函数、方法、属性、事件、类型或字段。
找到多个请求的属性。
无法加载自定义属性类型。
示例
下面的代码示例演示如何使用 GetCustomAttribute 采用参数 MemberInfo 的方法。
using namespace System;
using namespace System::Reflection;
namespace IsDef4CS
{
public ref class TestClass
{
public:
// Assign the Obsolete attribute to a method.
[Obsolete("This method is obsolete. Use Method2 instead.")]
void Method1(){}
void Method2(){}
};
ref class DemoClass
{
public:
static void Main()
{
// Get the class type to access its metadata.
Type^ clsType = TestClass::typeid;
// Get the MethodInfo object for Method1.
MethodInfo^ mInfo = clsType->GetMethod( "Method1" );
// See if the Obsolete attribute is defined for this method.
bool isDef = Attribute::IsDefined( mInfo, ObsoleteAttribute::typeid );
// Display the result.
Console::WriteLine( "The Obsolete Attribute {0} defined for {1} of class {2}.", isDef ? (String^)"is" : "is not", mInfo->Name, clsType->Name );
// If it's defined, display the attribute's message.
if ( isDef )
{
ObsoleteAttribute^ obsAttr = dynamic_cast<ObsoleteAttribute^>(Attribute::GetCustomAttribute( mInfo, ObsoleteAttribute::typeid ));
if ( obsAttr != nullptr )
Console::WriteLine( "The message is: \"{0}\".", obsAttr->Message );
else
Console::WriteLine( "The message could not be retrieved." );
}
}
};
}
/*
* Output:
* The Obsolete Attribute is defined for Method1 of class TestClass.
* The message is: "This method is obsolete. Use Method2 instead.".
*/
C#
using System;
using System.Reflection;
namespace IsDef4CS
{
public class TestClass
{
// Assign the Obsolete attribute to a method.
[Obsolete("This method is obsolete. Use Method2 instead.")]
public void Method1()
{}
public void Method2()
{}
}
public class DemoClass
{
static void Main(string[] args)
{
// Get the class type to access its metadata.
Type clsType = typeof(TestClass);
// Get the MethodInfo object for Method1.
MethodInfo mInfo = clsType.GetMethod("Method1");
// See if the Obsolete attribute is defined for this method.
bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
// Display the result.
Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
isDef ? "is" : "is not", mInfo.Name, clsType.Name);
// If it's defined, display the attribute's message.
if (isDef)
{
ObsoleteAttribute obsAttr =
(ObsoleteAttribute)Attribute.GetCustomAttribute(
mInfo, typeof(ObsoleteAttribute));
if (obsAttr != null)
Console.WriteLine("The message is: \"{0}\".",
obsAttr.Message);
else
Console.WriteLine("The message could not be retrieved.");
}
}
}
}
/*
* Output:
* The Obsolete Attribute is defined for Method1 of class TestClass.
* The message is: "This method is obsolete. Use Method2 instead.".
*/
open System
type TestClass() =
// Assign the Obsolete attribute to a method.
[<Obsolete "This method is obsolete. Use Method2 instead.">]
member _.Method1() = ()
member _.Method2() = ()
// Get the class type to access its metadata.
let clsType = typeof<TestClass>
// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"
// See if the Obsolete attribute is defined for this method.
let isDef = Attribute.IsDefined(mInfo, typeof<ObsoleteAttribute>)
// Display the result.
printfn $"""The Obsolete Attribute {if isDef then "is" else "is not"} defined for {mInfo.Name} of class {clsType.Name}."""
// If it's defined, display the attribute's message.
if isDef then
let obsAttr =
Attribute.GetCustomAttribute(mInfo, typeof<ObsoleteAttribute>)
:?> ObsoleteAttribute
if obsAttr <> null then
printfn $"The message is: \"{obsAttr.Message}\"."
else
printfn "The message could not be retrieved."
// Output:
// The Obsolete Attribute is defined for Method1 of class TestClass.
// The message is: "This method is obsolete. Use Method2 instead.".
Imports System.Reflection
Module DemoModule
Public Class TestClass
' Assign the Obsolete attribute to a method.
<Obsolete("This method is obsolete. Use Method2() instead.")> _
Public Sub Method1()
End Sub
Public Sub Method2()
End Sub
End Class
Sub Main()
' Get the class type to access its metadata.
Dim clsType As Type = GetType(TestClass)
' Get the MethodInfo object for Method1.
Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
' See if the Obsolete attribute is defined for this method.
Dim isDef As Boolean = Attribute.IsDefined(mInfo, _
GetType(ObsoleteAttribute))
Dim strDef As String
If isDef = True Then
strDef = "is"
Else
strDef = "is not"
End If
' Display the results.
Console.WriteLine("The Obsolete attribute {0} defined for " & _
"method {1} of class {2}.", strDef, mInfo.Name, clsType.Name)
' If it's defined, display the attribute's message.
If isDef = True Then
Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo, _
GetType(ObsoleteAttribute))
If Not attr Is Nothing And TypeOf attr Is ObsoleteAttribute Then
Dim obsAttr As ObsoleteAttribute = _
CType(attr, ObsoleteAttribute)
Console.WriteLine("The message is: ""{0}""", obsAttr.Message)
Else
Console.WriteLine("The message could not be retrieved.")
End If
End If
End Sub
End Module
' Output:
' The Obsolete attribute is defined for method Method1 of class TestClass.
' The message is: "This method is obsolete. Use Method2() instead."
注解
备注
从 .NET Framework 版本 2.0 开始，如果属性以新的元数据格式存储，此方法将返回类型、方法和构造函数的安全属性。 使用版本 2.0 或更高版本编译的程序集使用新格式。 使用早期版本的.NET Framework编译的动态程序集和程序集使用旧的 XML 格式。 请参阅 发出声明性安全属性。
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |
GetCustomAttribute(Assembly, Type, Boolean)
检索应用于程序集的自定义属性。 参数指定程序集、要搜索的自定义属性的类型以及忽略的搜索选项。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::Assembly ^ element, Type ^ attributeType, bool inherit);C#
public static Attribute? GetCustomAttribute (System.Reflection.Assembly element, Type attributeType, bool inherit);C#
public static Attribute GetCustomAttribute (System.Reflection.Assembly element, Type attributeType, bool inherit);static member GetCustomAttribute : System.Reflection.Assembly * Type * bool -> AttributePublic Shared Function GetCustomAttribute (element As Assembly, attributeType As Type, inherit As Boolean) As Attribute参数
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
- inherit
- Boolean
此参数被忽略，并且不会影响此方法的操作。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
找到多个请求的属性。
示例
下面的代码示例演示了采用 GetCustomAttribute 参数 Assembly 的方法的使用。
using namespace System;
using namespace System::Reflection;
// Add an AssemblyDescription attribute
[assembly:AssemblyDescription("A sample description")];
namespace IsDef1CS
{
ref class DemoClass
{
public:
static void Main()
{
// Get the class type to access its metadata.
Type^ clsType = DemoClass::typeid;
// Get the assembly object.
Assembly^ assy = clsType->Assembly;
// Store the assembly's name.
String^ assyName = assy->GetName()->Name;
//Type assyType = assy.GetType();
// See if the Assembly Description is defined.
bool isdef = Attribute::IsDefined( assy, AssemblyDescriptionAttribute::typeid );
if ( isdef )
{
// Affirm that the attribute is defined.
Console::WriteLine( "The AssemblyDescription attribute "
"is defined for assembly {0}.", assyName );
// Get the description attribute itself.
AssemblyDescriptionAttribute^ adAttr = dynamic_cast<AssemblyDescriptionAttribute^>(Attribute::GetCustomAttribute( assy, AssemblyDescriptionAttribute::typeid ));
// Display the description.
if ( adAttr != nullptr )
Console::WriteLine( "The description is \"{0}\".", adAttr->Description );
else
Console::WriteLine( "The description could not "
"be retrieved." );
}
else
Console::WriteLine( "The AssemblyDescription attribute is not "
"defined for assembly {0}.", assyName );
}
};
}
/*
* Output:
* The AssemblyDescription attributeis defined for assembly IsDef1CS.
* The description is "A sample description".
*/
C#
using System;
using System.Reflection;
// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]
namespace IsDef1CS
{
public class DemoClass
{
static void Main(string[] args)
{
// Get the class type to access its metadata.
Type clsType = typeof(DemoClass);
// Get the assembly object.
Assembly assy = clsType.Assembly;
// Store the assembly's name.
String assyName = assy.GetName().Name;
// See if the Assembly Description is defined.
bool isdef = Attribute.IsDefined(assy,
typeof(AssemblyDescriptionAttribute));
if (isdef)
{
// Affirm that the attribute is defined.
Console.WriteLine("The AssemblyDescription attribute " +
"is defined for assembly {0}.", assyName);
// Get the description attribute itself.
AssemblyDescriptionAttribute adAttr =
(AssemblyDescriptionAttribute)Attribute.GetCustomAttribute(
assy, typeof(AssemblyDescriptionAttribute));
// Display the description.
if (adAttr != null)
Console.WriteLine("The description is \"{0}\".",
adAttr.Description);
else
Console.WriteLine("The description could not " +
"be retrieved.");
}
else
Console.WriteLine("The AssemblyDescription attribute is not " +
"defined for assembly {0}.", assyName);
}
}
}
/*
* Output:
* The AssemblyDescription attribute is defined for assembly IsDef1CS.
* The description is "A sample description".
*/
open System
open System.Reflection
// Add an AssemblyDescription attribute
[<assembly: AssemblyDescription "A sample description">]
do ()
type DemoClass = class end
// Get the class type to access its metadata.
let clsType = typeof<DemoClass>
// Get the assembly object.
let assembly = clsType.Assembly;
// Store the assembly's name.
let assemblyName = assembly.GetName().Name
// See if the Assembly Description is defined.
let isdef =
Attribute.IsDefined(assembly, typeof<AssemblyDescriptionAttribute>)
if isdef then
// Affirm that the attribute is defined.
printfn $"The AssemblyDescription attribute is defined for assembly {assemblyName}."
// Get the description attribute itself.
let adAttr =
Attribute.GetCustomAttribute(assembly, typeof<AssemblyDescriptionAttribute>)
:?> AssemblyDescriptionAttribute
// Display the description.
if adAttr <> null then
printfn $"The description is \"{adAttr.Description}\"."
else
printfn $"The description could not be retrieved."
else
printfn $"The AssemblyDescription attribute is not defined for assembly {assemblyName}."
// Output:
// The AssemblyDescription attribute is defined for assembly IsDef1FS.
// The description is "A sample description".
Imports System.Reflection
' Add an AssemblyDescription attribute.
<Assembly: AssemblyDescription("A sample description")>
Module DemoModule
Sub Main()
' Get the assembly for this module.
Dim assy As System.Reflection.Assembly = GetType(DemoModule).Assembly
' Store the assembly name.
Dim assyName As String = assy.GetName().Name
' See if the AssemblyDescription attribute is defined.
If Attribute.IsDefined(assy, GetType(AssemblyDescriptionAttribute)) _
Then
' Affirm that the attribute is defined. Assume the filename of
' this code example is "IsDef1VB".
Console.WriteLine("The AssemblyDescription attribute is " & _
"defined for assembly {0}.", assyName)
' Get the description attribute itself.
Dim attr As Attribute = Attribute.GetCustomAttribute( _
assy, GetType(AssemblyDescriptionAttribute))
' Display the description.
If Not attr Is Nothing And _
TypeOf attr Is AssemblyDescriptionAttribute Then
Dim adAttr As AssemblyDescriptionAttribute = _
CType(attr, AssemblyDescriptionAttribute)
Console.WriteLine("The description is " & _
Chr(34) & "{0}" & Chr(34) & ".", adAttr.Description)
Else
Console.WriteLine("The description could not be retrieved.")
End If
Else
Console.WriteLine("The AssemblyDescription attribute is not " & _
"defined for assembly {0}.", assyName)
End If
End Sub
End Module
' Output:
' The AssemblyDescription attribute is defined for assembly IsDef1VB.
' The description is "A sample description".
注解
备注
从 .NET Framework 版本 2.0 开始，如果属性以新的元数据格式存储，此方法将返回安全属性。 使用版本 2.0 或更高版本编译的程序集使用新格式。 使用早期版本的.NET Framework编译的动态程序集和程序集使用旧的 XML 格式。 请参阅 发出声明性安全属性。
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |
GetCustomAttribute(Module, Type, Boolean)
检索应用于模块的自定义属性。 参数指定模块、要搜索的自定义属性的类型以及忽略的搜索选项。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::Module ^ element, Type ^ attributeType, bool inherit);C#
public static Attribute? GetCustomAttribute (System.Reflection.Module element, Type attributeType, bool inherit);C#
public static Attribute GetCustomAttribute (System.Reflection.Module element, Type attributeType, bool inherit);static member GetCustomAttribute : System.Reflection.Module * Type * bool -> AttributePublic Shared Function GetCustomAttribute (element As Module, attributeType As Type, inherit As Boolean) As Attribute参数
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
- inherit
- Boolean
此参数被忽略，并且不会影响此方法的操作。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
找到多个请求的属性。
示例
下面的代码示例演示如何使用 GetCustomAttribute 采用参数 Module 的方法。
using namespace System;
using namespace System::Diagnostics;
// Add the Debuggable attribute to the module.
[module:Debuggable(true,false)];
namespace IsDef2CS
{
ref class DemoClass
{
public:
static void Main()
{
// Get the class type to access its metadata.
Type^ clsType = DemoClass::typeid;
// See if the Debuggable attribute is defined for this module.
bool isDef = Attribute::IsDefined( clsType->Module, DebuggableAttribute::typeid );
// Display the result.
Console::WriteLine( "The Debuggable attribute {0} "
"defined for Module {1}.", isDef ? (String^)"is" : "is not", clsType->Module->Name );
// If the attribute is defined, display the JIT settings.
if ( isDef )
{
// Retrieve the attribute itself.
DebuggableAttribute^ dbgAttr = dynamic_cast<DebuggableAttribute^>(Attribute::GetCustomAttribute( clsType->Module, DebuggableAttribute::typeid ));
if ( dbgAttr != nullptr )
{
Console::WriteLine( "JITTrackingEnabled is {0}.", dbgAttr->IsJITTrackingEnabled );
Console::WriteLine( "JITOptimizerDisabled is {0}.", dbgAttr->IsJITOptimizerDisabled );
}
else
Console::WriteLine( "The Debuggable attribute "
"could not be retrieved." );
}
}
};
}
/*
* Output:
* The Debuggable attribute is defined for Module IsDef2CS.exe.
* JITTrackingEnabled is True.
* JITOptimizerDisabled is False.
*/
C#
using System;
using System.Diagnostics;
// Add the Debuggable attribute to the module.
[module:Debuggable(true, false)]
namespace IsDef2CS
{
public class DemoClass
{
static void Main(string[] args)
{
// Get the class type to access its metadata.
Type clsType = typeof(DemoClass);
// See if the Debuggable attribute is defined for this module.
bool isDef = Attribute.IsDefined(clsType.Module,
typeof(DebuggableAttribute));
// Display the result.
Console.WriteLine("The Debuggable attribute {0} " +
"defined for Module {1}.",
isDef ? "is" : "is not",
clsType.Module.Name);
// If the attribute is defined, display the JIT settings.
if (isDef)
{
// Retrieve the attribute itself.
DebuggableAttribute dbgAttr = (DebuggableAttribute)
Attribute.GetCustomAttribute(clsType.Module,
typeof(DebuggableAttribute));
if (dbgAttr != null)
{
Console.WriteLine("JITTrackingEnabled is {0}.",
dbgAttr.IsJITTrackingEnabled);
Console.WriteLine("JITOptimizerDisabled is {0}.",
dbgAttr.IsJITOptimizerDisabled);
}
else
Console.WriteLine("The Debuggable attribute " +
"could not be retrieved.");
}
}
}
}
/*
* Output:
* The Debuggable attribute is defined for Module IsDef2CS.exe.
* JITTrackingEnabled is True.
* JITOptimizerDisabled is False.
*/
open System
open System.Diagnostics
// Add the Debuggable attribute to the module.
[<``module``: Debuggable(true, false)>]
do ()
type DemoClass = class end
// Get the class type to access its metadata.
let clsType = typeof<DemoClass>
// See if the Debuggable attribute is defined for this module.
let isDef = Attribute.IsDefined(clsType.Module, typeof<DebuggableAttribute>)
// Display the result.
printfn $"""The Debuggable attribute {if isDef then "is" else "is not"} defined for Module {clsType.Module.Name}."""
// If the attribute is defined, display the JIT settings.
if isDef then
// Retrieve the attribute itself.
let dbgAttr =
Attribute.GetCustomAttribute(clsType.Module, typeof<DebuggableAttribute>)
:?> DebuggableAttribute
if dbgAttr <> null then
printfn $"JITTrackingEnabled is {dbgAttr.IsJITTrackingEnabled}."
printfn $"JITOptimizerDisabled is {dbgAttr.IsJITOptimizerDisabled}."
else
printfn "The Debuggable attribute could not be retrieved."
// Output:
// The Debuggable attribute is defined for Module IsDef2CS.exe.
// JITTrackingEnabled is True.
// JITOptimizerDisabled is False.
Imports System.Reflection
Imports System.Diagnostics
' Add the Debuggable attribute to the module.
<Module: Debuggable(True, False)>
Module DemoModule
Sub Main()
' Get the module type information to access its metadata.
Dim modType As Type = GetType(DemoModule)
' See if the Debuggable attribute is defined.
Dim isDef As Boolean = Attribute.IsDefined(modType.Module, _
GetType(DebuggableAttribute))
Dim strDef As String
If isDef = True Then
strDef = "is"
Else
strDef = "is not"
End If
' Display the result
Console.WriteLine("The debuggable attribute {0} defined for " & _
"module {1}.", strDef, modType.Name)
' If the attribute is defined, display the JIT settings.
If isDef = True Then
' Retrieve the attribute itself.
Dim attr As Attribute = _
Attribute.GetCustomAttribute(modType.Module, _
GetType(DebuggableAttribute))
If Not attr Is Nothing And TypeOf attr Is DebuggableAttribute Then
Dim dbgAttr As DebuggableAttribute = _
CType(attr, DebuggableAttribute)
Console.WriteLine("JITTrackingEnabled is {0}.", _
dbgAttr.IsJITTrackingEnabled.ToString())
Console.WriteLine("JITOptimizerDisabled is {0}.", _
dbgAttr.IsJITOptimizerDisabled.ToString())
Else
Console.WriteLine("The Debuggable attribute could " & _
"not be retrieved.")
End If
End If
End Sub
End Module
' Output:
' The debuggable attribute is defined for module DemoModule.
' JITTrackingEnabled is True.
' JITOptimizerDisabled is False.
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |
GetCustomAttribute(Module, Type)
检索应用于模块的自定义属性。 参数指定模块和要搜索的自定义属性的类型。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::Module ^ element, Type ^ attributeType);C#
public static Attribute? GetCustomAttribute (System.Reflection.Module element, Type attributeType);C#
public static Attribute GetCustomAttribute (System.Reflection.Module element, Type attributeType);static member GetCustomAttribute : System.Reflection.Module * Type -> AttributePublic Shared Function GetCustomAttribute (element As Module, attributeType As Type) As Attribute参数
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
找到多个请求的属性。
示例
下面的代码示例演示如何使用 GetCustomAttribute 采用参数 Module 的方法。
using namespace System;
using namespace System::Diagnostics;
// Add the Debuggable attribute to the module.
[module:Debuggable(true,false)];
namespace IsDef2CS
{
ref class DemoClass
{
public:
static void Main()
{
// Get the class type to access its metadata.
Type^ clsType = DemoClass::typeid;
// See if the Debuggable attribute is defined for this module.
bool isDef = Attribute::IsDefined( clsType->Module, DebuggableAttribute::typeid );
// Display the result.
Console::WriteLine( "The Debuggable attribute {0} "
"defined for Module {1}.", isDef ? (String^)"is" : "is not", clsType->Module->Name );
// If the attribute is defined, display the JIT settings.
if ( isDef )
{
// Retrieve the attribute itself.
DebuggableAttribute^ dbgAttr = dynamic_cast<DebuggableAttribute^>(Attribute::GetCustomAttribute( clsType->Module, DebuggableAttribute::typeid ));
if ( dbgAttr != nullptr )
{
Console::WriteLine( "JITTrackingEnabled is {0}.", dbgAttr->IsJITTrackingEnabled );
Console::WriteLine( "JITOptimizerDisabled is {0}.", dbgAttr->IsJITOptimizerDisabled );
}
else
Console::WriteLine( "The Debuggable attribute "
"could not be retrieved." );
}
}
};
}
/*
* Output:
* The Debuggable attribute is defined for Module IsDef2CS.exe.
* JITTrackingEnabled is True.
* JITOptimizerDisabled is False.
*/
C#
using System;
using System.Diagnostics;
// Add the Debuggable attribute to the module.
[module:Debuggable(true, false)]
namespace IsDef2CS
{
public class DemoClass
{
static void Main(string[] args)
{
// Get the class type to access its metadata.
Type clsType = typeof(DemoClass);
// See if the Debuggable attribute is defined for this module.
bool isDef = Attribute.IsDefined(clsType.Module,
typeof(DebuggableAttribute));
// Display the result.
Console.WriteLine("The Debuggable attribute {0} " +
"defined for Module {1}.",
isDef ? "is" : "is not",
clsType.Module.Name);
// If the attribute is defined, display the JIT settings.
if (isDef)
{
// Retrieve the attribute itself.
DebuggableAttribute dbgAttr = (DebuggableAttribute)
Attribute.GetCustomAttribute(clsType.Module,
typeof(DebuggableAttribute));
if (dbgAttr != null)
{
Console.WriteLine("JITTrackingEnabled is {0}.",
dbgAttr.IsJITTrackingEnabled);
Console.WriteLine("JITOptimizerDisabled is {0}.",
dbgAttr.IsJITOptimizerDisabled);
}
else
Console.WriteLine("The Debuggable attribute " +
"could not be retrieved.");
}
}
}
}
/*
* Output:
* The Debuggable attribute is defined for Module IsDef2CS.exe.
* JITTrackingEnabled is True.
* JITOptimizerDisabled is False.
*/
open System
open System.Diagnostics
// Add the Debuggable attribute to the module.
[<``module``: Debuggable(true, false)>]
do ()
type DemoClass = class end
// Get the class type to access its metadata.
let clsType = typeof<DemoClass>
// See if the Debuggable attribute is defined for this module.
let isDef = Attribute.IsDefined(clsType.Module, typeof<DebuggableAttribute>)
// Display the result.
printfn $"""The Debuggable attribute {if isDef then "is" else "is not"} defined for Module {clsType.Module.Name}."""
// If the attribute is defined, display the JIT settings.
if isDef then
// Retrieve the attribute itself.
let dbgAttr =
Attribute.GetCustomAttribute(clsType.Module, typeof<DebuggableAttribute>)
:?> DebuggableAttribute
if dbgAttr <> null then
printfn $"JITTrackingEnabled is {dbgAttr.IsJITTrackingEnabled}."
printfn $"JITOptimizerDisabled is {dbgAttr.IsJITOptimizerDisabled}."
else
printfn "The Debuggable attribute could not be retrieved."
// Output:
// The Debuggable attribute is defined for Module IsDef2CS.exe.
// JITTrackingEnabled is True.
// JITOptimizerDisabled is False.
Imports System.Reflection
Imports System.Diagnostics
' Add the Debuggable attribute to the module.
<Module: Debuggable(True, False)>
Module DemoModule
Sub Main()
' Get the module type information to access its metadata.
Dim modType As Type = GetType(DemoModule)
' See if the Debuggable attribute is defined.
Dim isDef As Boolean = Attribute.IsDefined(modType.Module, _
GetType(DebuggableAttribute))
Dim strDef As String
If isDef = True Then
strDef = "is"
Else
strDef = "is not"
End If
' Display the result
Console.WriteLine("The debuggable attribute {0} defined for " & _
"module {1}.", strDef, modType.Name)
' If the attribute is defined, display the JIT settings.
If isDef = True Then
' Retrieve the attribute itself.
Dim attr As Attribute = _
Attribute.GetCustomAttribute(modType.Module, _
GetType(DebuggableAttribute))
If Not attr Is Nothing And TypeOf attr Is DebuggableAttribute Then
Dim dbgAttr As DebuggableAttribute = _
CType(attr, DebuggableAttribute)
Console.WriteLine("JITTrackingEnabled is {0}.", _
dbgAttr.IsJITTrackingEnabled.ToString())
Console.WriteLine("JITOptimizerDisabled is {0}.", _
dbgAttr.IsJITOptimizerDisabled.ToString())
Else
Console.WriteLine("The Debuggable attribute could " & _
"not be retrieved.")
End If
End If
End Sub
End Module
' Output:
' The debuggable attribute is defined for module DemoModule.
' JITTrackingEnabled is True.
' JITOptimizerDisabled is False.
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |
GetCustomAttribute(MemberInfo, Type)
检索应用于类型成员的自定义属性。 参数指定成员和要搜索的自定义属性的类型。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::MemberInfo ^ element, Type ^ attributeType);C#
public static Attribute? GetCustomAttribute (System.Reflection.MemberInfo element, Type attributeType);C#
public static Attribute GetCustomAttribute (System.Reflection.MemberInfo element, Type attributeType);static member GetCustomAttribute : System.Reflection.MemberInfo * Type -> AttributePublic Shared Function GetCustomAttribute (element As MemberInfo, attributeType As Type) As Attribute参数
- element
- MemberInfo
一个从 MemberInfo 类派生的对象，该类描述类的构造函数、事件、字段、方法或属性成员。
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
element 不是构造函数、方法、属性、事件、类型或字段。
找到多个请求的属性。
无法加载自定义属性类型。
示例
下面的代码示例演示如何使用 GetCustomAttribute 采用参数 MemberInfo 的方法。
using namespace System;
using namespace System::Reflection;
namespace IsDef4CS
{
public ref class TestClass
{
public:
// Assign the Obsolete attribute to a method.
[Obsolete("This method is obsolete. Use Method2 instead.")]
void Method1(){}
void Method2(){}
};
ref class DemoClass
{
public:
static void Main()
{
// Get the class type to access its metadata.
Type^ clsType = TestClass::typeid;
// Get the MethodInfo object for Method1.
MethodInfo^ mInfo = clsType->GetMethod( "Method1" );
// See if the Obsolete attribute is defined for this method.
bool isDef = Attribute::IsDefined( mInfo, ObsoleteAttribute::typeid );
// Display the result.
Console::WriteLine( "The Obsolete Attribute {0} defined for {1} of class {2}.", isDef ? (String^)"is" : "is not", mInfo->Name, clsType->Name );
// If it's defined, display the attribute's message.
if ( isDef )
{
ObsoleteAttribute^ obsAttr = dynamic_cast<ObsoleteAttribute^>(Attribute::GetCustomAttribute( mInfo, ObsoleteAttribute::typeid ));
if ( obsAttr != nullptr )
Console::WriteLine( "The message is: \"{0}\".", obsAttr->Message );
else
Console::WriteLine( "The message could not be retrieved." );
}
}
};
}
/*
* Output:
* The Obsolete Attribute is defined for Method1 of class TestClass.
* The message is: "This method is obsolete. Use Method2 instead.".
*/
C#
using System;
using System.Reflection;
namespace IsDef4CS
{
public class TestClass
{
// Assign the Obsolete attribute to a method.
[Obsolete("This method is obsolete. Use Method2 instead.")]
public void Method1()
{}
public void Method2()
{}
}
public class DemoClass
{
static void Main(string[] args)
{
// Get the class type to access its metadata.
Type clsType = typeof(TestClass);
// Get the MethodInfo object for Method1.
MethodInfo mInfo = clsType.GetMethod("Method1");
// See if the Obsolete attribute is defined for this method.
bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
// Display the result.
Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
isDef ? "is" : "is not", mInfo.Name, clsType.Name);
// If it's defined, display the attribute's message.
if (isDef)
{
ObsoleteAttribute obsAttr =
(ObsoleteAttribute)Attribute.GetCustomAttribute(
mInfo, typeof(ObsoleteAttribute));
if (obsAttr != null)
Console.WriteLine("The message is: \"{0}\".",
obsAttr.Message);
else
Console.WriteLine("The message could not be retrieved.");
}
}
}
}
/*
* Output:
* The Obsolete Attribute is defined for Method1 of class TestClass.
* The message is: "This method is obsolete. Use Method2 instead.".
*/
open System
type TestClass() =
// Assign the Obsolete attribute to a method.
[<Obsolete "This method is obsolete. Use Method2 instead.">]
member _.Method1() = ()
member _.Method2() = ()
// Get the class type to access its metadata.
let clsType = typeof<TestClass>
// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"
// See if the Obsolete attribute is defined for this method.
let isDef = Attribute.IsDefined(mInfo, typeof<ObsoleteAttribute>)
// Display the result.
printfn $"""The Obsolete Attribute {if isDef then "is" else "is not"} defined for {mInfo.Name} of class {clsType.Name}."""
// If it's defined, display the attribute's message.
if isDef then
let obsAttr =
Attribute.GetCustomAttribute(mInfo, typeof<ObsoleteAttribute>)
:?> ObsoleteAttribute
if obsAttr <> null then
printfn $"The message is: \"{obsAttr.Message}\"."
else
printfn "The message could not be retrieved."
// Output:
// The Obsolete Attribute is defined for Method1 of class TestClass.
// The message is: "This method is obsolete. Use Method2 instead.".
Imports System.Reflection
Module DemoModule
Public Class TestClass
' Assign the Obsolete attribute to a method.
<Obsolete("This method is obsolete. Use Method2() instead.")> _
Public Sub Method1()
End Sub
Public Sub Method2()
End Sub
End Class
Sub Main()
' Get the class type to access its metadata.
Dim clsType As Type = GetType(TestClass)
' Get the MethodInfo object for Method1.
Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
' See if the Obsolete attribute is defined for this method.
Dim isDef As Boolean = Attribute.IsDefined(mInfo, _
GetType(ObsoleteAttribute))
Dim strDef As String
If isDef = True Then
strDef = "is"
Else
strDef = "is not"
End If
' Display the results.
Console.WriteLine("The Obsolete attribute {0} defined for " & _
"method {1} of class {2}.", strDef, mInfo.Name, clsType.Name)
' If it's defined, display the attribute's message.
If isDef = True Then
Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo, _
GetType(ObsoleteAttribute))
If Not attr Is Nothing And TypeOf attr Is ObsoleteAttribute Then
Dim obsAttr As ObsoleteAttribute = _
CType(attr, ObsoleteAttribute)
Console.WriteLine("The message is: ""{0}""", obsAttr.Message)
Else
Console.WriteLine("The message could not be retrieved.")
End If
End If
End Sub
End Module
' Output:
' The Obsolete attribute is defined for method Method1 of class TestClass.
' The message is: "This method is obsolete. Use Method2() instead."
注解
匹配项的确定方式与 “返回值”部分 Type.IsAssignableFrom中所述的方式相同。
备注
从 .NET Framework 版本 2.0 开始，如果属性以新的元数据格式存储，此方法将返回类型、方法和构造函数的安全属性。 使用版本 2.0 或更高版本编译的程序集使用新格式。 使用早期版本的.NET Framework编译的动态程序集和程序集使用旧的 XML 格式。 请参阅 发出声明性安全属性。
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |
GetCustomAttribute(Assembly, Type)
检索应用于指定程序集的自定义属性。 参数指定程序集和要搜索的自定义属性的类型。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::Assembly ^ element, Type ^ attributeType);C#
public static Attribute? GetCustomAttribute (System.Reflection.Assembly element, Type attributeType);C#
public static Attribute GetCustomAttribute (System.Reflection.Assembly element, Type attributeType);static member GetCustomAttribute : System.Reflection.Assembly * Type -> AttributePublic Shared Function GetCustomAttribute (element As Assembly, attributeType As Type) As Attribute参数
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
找到多个请求的属性。
示例
下面的代码示例演示了采用 GetCustomAttribute 参数 Assembly 的方法的使用。
using namespace System;
using namespace System::Reflection;
// Add an AssemblyDescription attribute
[assembly:AssemblyDescription("A sample description")];
namespace IsDef1CS
{
ref class DemoClass
{
public:
static void Main()
{
// Get the class type to access its metadata.
Type^ clsType = DemoClass::typeid;
// Get the assembly object.
Assembly^ assy = clsType->Assembly;
// Store the assembly's name.
String^ assyName = assy->GetName()->Name;
//Type assyType = assy.GetType();
// See if the Assembly Description is defined.
bool isdef = Attribute::IsDefined( assy, AssemblyDescriptionAttribute::typeid );
if ( isdef )
{
// Affirm that the attribute is defined.
Console::WriteLine( "The AssemblyDescription attribute "
"is defined for assembly {0}.", assyName );
// Get the description attribute itself.
AssemblyDescriptionAttribute^ adAttr = dynamic_cast<AssemblyDescriptionAttribute^>(Attribute::GetCustomAttribute( assy, AssemblyDescriptionAttribute::typeid ));
// Display the description.
if ( adAttr != nullptr )
Console::WriteLine( "The description is \"{0}\".", adAttr->Description );
else
Console::WriteLine( "The description could not "
"be retrieved." );
}
else
Console::WriteLine( "The AssemblyDescription attribute is not "
"defined for assembly {0}.", assyName );
}
};
}
/*
* Output:
* The AssemblyDescription attributeis defined for assembly IsDef1CS.
* The description is "A sample description".
*/
C#
using System;
using System.Reflection;
// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]
namespace IsDef1CS
{
public class DemoClass
{
static void Main(string[] args)
{
// Get the class type to access its metadata.
Type clsType = typeof(DemoClass);
// Get the assembly object.
Assembly assy = clsType.Assembly;
// Store the assembly's name.
String assyName = assy.GetName().Name;
// See if the Assembly Description is defined.
bool isdef = Attribute.IsDefined(assy,
typeof(AssemblyDescriptionAttribute));
if (isdef)
{
// Affirm that the attribute is defined.
Console.WriteLine("The AssemblyDescription attribute " +
"is defined for assembly {0}.", assyName);
// Get the description attribute itself.
AssemblyDescriptionAttribute adAttr =
(AssemblyDescriptionAttribute)Attribute.GetCustomAttribute(
assy, typeof(AssemblyDescriptionAttribute));
// Display the description.
if (adAttr != null)
Console.WriteLine("The description is \"{0}\".",
adAttr.Description);
else
Console.WriteLine("The description could not " +
"be retrieved.");
}
else
Console.WriteLine("The AssemblyDescription attribute is not " +
"defined for assembly {0}.", assyName);
}
}
}
/*
* Output:
* The AssemblyDescription attribute is defined for assembly IsDef1CS.
* The description is "A sample description".
*/
open System
open System.Reflection
// Add an AssemblyDescription attribute
[<assembly: AssemblyDescription "A sample description">]
do ()
type DemoClass = class end
// Get the class type to access its metadata.
let clsType = typeof<DemoClass>
// Get the assembly object.
let assembly = clsType.Assembly;
// Store the assembly's name.
let assemblyName = assembly.GetName().Name
// See if the Assembly Description is defined.
let isdef =
Attribute.IsDefined(assembly, typeof<AssemblyDescriptionAttribute>)
if isdef then
// Affirm that the attribute is defined.
printfn $"The AssemblyDescription attribute is defined for assembly {assemblyName}."
// Get the description attribute itself.
let adAttr =
Attribute.GetCustomAttribute(assembly, typeof<AssemblyDescriptionAttribute>)
:?> AssemblyDescriptionAttribute
// Display the description.
if adAttr <> null then
printfn $"The description is \"{adAttr.Description}\"."
else
printfn $"The description could not be retrieved."
else
printfn $"The AssemblyDescription attribute is not defined for assembly {assemblyName}."
// Output:
// The AssemblyDescription attribute is defined for assembly IsDef1FS.
// The description is "A sample description".
Imports System.Reflection
' Add an AssemblyDescription attribute.
<Assembly: AssemblyDescription("A sample description")>
Module DemoModule
Sub Main()
' Get the assembly for this module.
Dim assy As System.Reflection.Assembly = GetType(DemoModule).Assembly
' Store the assembly name.
Dim assyName As String = assy.GetName().Name
' See if the AssemblyDescription attribute is defined.
If Attribute.IsDefined(assy, GetType(AssemblyDescriptionAttribute)) _
Then
' Affirm that the attribute is defined. Assume the filename of
' this code example is "IsDef1VB".
Console.WriteLine("The AssemblyDescription attribute is " & _
"defined for assembly {0}.", assyName)
' Get the description attribute itself.
Dim attr As Attribute = Attribute.GetCustomAttribute( _
assy, GetType(AssemblyDescriptionAttribute))
' Display the description.
If Not attr Is Nothing And _
TypeOf attr Is AssemblyDescriptionAttribute Then
Dim adAttr As AssemblyDescriptionAttribute = _
CType(attr, AssemblyDescriptionAttribute)
Console.WriteLine("The description is " & _
Chr(34) & "{0}" & Chr(34) & ".", adAttr.Description)
Else
Console.WriteLine("The description could not be retrieved.")
End If
Else
Console.WriteLine("The AssemblyDescription attribute is not " & _
"defined for assembly {0}.", assyName)
End If
End Sub
End Module
' Output:
' The AssemblyDescription attribute is defined for assembly IsDef1VB.
' The description is "A sample description".
注解
GetCustomAttributes如果希望返回多个值或将引发，AmbiguousMatchException请使用该方法。
备注
从 .NET Framework 版本 2.0 开始，如果属性以新的元数据格式存储，此方法将返回安全属性。 使用版本 2.0 或更高版本编译的程序集使用新格式。 使用早期版本的.NET Framework编译的动态程序集和程序集使用旧的 XML 格式。 请参阅 发出声明性安全属性。
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |
GetCustomAttribute(ParameterInfo, Type)
检索应用于方法参数的自定义属性。 参数指定方法参数和要搜索的自定义属性的类型。
public:
static Attribute ^ GetCustomAttribute(System::Reflection::ParameterInfo ^ element, Type ^ attributeType);C#
public static Attribute? GetCustomAttribute (System.Reflection.ParameterInfo element, Type attributeType);C#
public static Attribute GetCustomAttribute (System.Reflection.ParameterInfo element, Type attributeType);static member GetCustomAttribute : System.Reflection.ParameterInfo * Type -> AttributePublic Shared Function GetCustomAttribute (element As ParameterInfo, attributeType As Type) As Attribute参数
- element
- ParameterInfo
一个从 ParameterInfo 类派生的对象，该类描述类成员的参数。
- attributeType
- Type
要搜索的自定义属性的类型或基类型。
返回
一个引用，指向应用于 attributeType 的 element 类型的单个自定义属性；如果没有此类属性，则为 null。
例外
element 或 attributeType 为 null。
attributeType 不是从 Attribute 派生的。
找到多个请求的属性。
无法加载自定义属性类型。
示例
下面的代码示例定义自定义参数 Attribute 类，并将自定义属性应用于派生类和派生类的基的方法。 该示例演示如何使用 GetCustomAttribute 该方法返回属性。
// Example for the Attribute::GetCustomAttribute( ParameterInfo*, Type* )
// method.
using namespace System;
using namespace System::Collections;
using namespace System::Reflection;
namespace NDP_UE_CPP
{
// Define a custom parameter attribute that takes a single message argument.
[AttributeUsage(AttributeTargets::Parameter)]
public ref class ArgumentUsageAttribute: public Attribute
{
protected:
// usageMsg is storage for the attribute message.
String^ usageMsg;
public:
// This is the attribute constructor.
ArgumentUsageAttribute( String^ UsageMsg )
{
this->usageMsg = UsageMsg;
}
property String^ Message
{
// This is the Message property for the attribute.
String^ get()
{
return usageMsg;
}
void set( String^ value )
{
this->usageMsg = value;
}
}
};
public ref class BaseClass
{
public:
// Assign an ArgumentUsage attribute to the strArray parameter.
// Assign a ParamArray attribute to strList.
virtual void TestMethod( [ArgumentUsage("Must pass an array here.")]array<String^>^strArray,
...array<String^>^strList ){}
};
public ref class DerivedClass: public BaseClass
{
public:
// Assign an ArgumentUsage attributes to the strList parameter.
virtual void TestMethod( array<String^>^strArray, [ArgumentUsage(
"Can pass a parameter list or array here.")]array<String^>^strList ) override {}
};
}
int main()
{
Console::WriteLine( "This example of Attribute::GetCustomAttribute( Param"
"eterInfo*, Type* )\ngenerates the following output." );
// Get the class type, and then get the MethodInfo object
// for TestMethod to access its metadata.
Type^ clsType = NDP_UE_CPP::DerivedClass::typeid;
MethodInfo^ mInfo = clsType->GetMethod( "TestMethod" );
// Iterate through the ParameterInfo array for the method parameters.
array<ParameterInfo^>^pInfoArray = mInfo->GetParameters();
if ( pInfoArray != nullptr )
{
// This implements foreach( ParameterInfo* paramInfo in pInfoArray ).
IEnumerator^ myEnum = pInfoArray->GetEnumerator();
while ( myEnum->MoveNext() )
{
ParameterInfo^ paramInfo = safe_cast<ParameterInfo^>(myEnum->Current);
// See if the ParamArray attribute is defined.
bool isDef = Attribute::IsDefined( paramInfo, ParamArrayAttribute::typeid );
if ( isDef )
Console::WriteLine( "\nThe ParamArray attribute is defined for \n"
"parameter {0} of method {1}.", paramInfo->Name, mInfo->Name );
// See if ParamUsageAttribute is defined.
// If so, display a message.
NDP_UE_CPP::ArgumentUsageAttribute^ usageAttr = static_cast<NDP_UE_CPP::ArgumentUsageAttribute^>(Attribute::GetCustomAttribute( paramInfo, NDP_UE_CPP::ArgumentUsageAttribute::typeid ));
if ( usageAttr != nullptr )
{
Console::WriteLine( "\nThe ArgumentUsage attribute is defined for \n"
"parameter {0} of method {1}.", paramInfo->Name, mInfo->Name );
Console::WriteLine( "\n The usage "
"message for {0} is:\n \"{1}\".", paramInfo->Name, usageAttr->Message );
}
}
}
else
Console::WriteLine( "The parameters information could "
"not be retrieved for method {0}.", mInfo->Name );
}
/*
This example of Attribute::GetCustomAttribute( ParameterInfo*, Type* )
generates the following output.
The ArgumentUsage attribute is defined for
parameter strArray of method TestMethod.
The usage message for strArray is:
"Must pass an array here.".
The ParamArray attribute is defined for
parameter strList of method TestMethod.
The ArgumentUsage attribute is defined for
parameter strList of method TestMethod.
The usage message for strList is:
"Can pass a parameter list or array here.".
*/
C#
// Example for the Attribute.GetCustomAttribute( ParameterInfo, Type ) method.
using System;
using System.Reflection;
namespace NDP_UE_CS
{
// Define a custom parameter attribute that takes a single message argument.
[AttributeUsage( AttributeTargets.Parameter )]
public class ArgumentUsageAttribute : Attribute
{
// This is the attribute constructor.
public ArgumentUsageAttribute( string UsageMsg )
{
this.usageMsg = UsageMsg;
}
// usageMsg is storage for the attribute message.
protected string usageMsg;
// This is the Message property for the attribute.
public string Message
{
get { return usageMsg; }
set { usageMsg = value; }
}
}
public class BaseClass
{
// Assign an ArgumentUsage attribute to the strArray parameter.
// Assign a ParamArray attribute to strList using the params keyword.
public virtual void TestMethod(
[ArgumentUsage("Must pass an array here.")]
String[] strArray,
params String[] strList)
{ }
}
public class DerivedClass : BaseClass
{
// Assign an ArgumentUsage attribute to the strList parameter.
// Assign a ParamArray attribute to strList using the params keyword.
public override void TestMethod(
String[] strArray,
[ArgumentUsage("Can pass a parameter list or array here.")]
params String[] strList)
{ }
}
class CustomParamDemo
{
static void Main( )
{
Console.WriteLine(
"This example of Attribute.GetCustomAttribute( Param" +
"eterInfo, Type )\ngenerates the following output." );
// Get the class type, and then get the MethodInfo object
// for TestMethod to access its metadata.
Type clsType = typeof( DerivedClass );
MethodInfo mInfo = clsType.GetMethod("TestMethod");
// Iterate through the ParameterInfo array for the method parameters.
ParameterInfo[] pInfoArray = mInfo.GetParameters();
if (pInfoArray != null)
{
foreach( ParameterInfo paramInfo in pInfoArray )
{
// See if the ParamArray attribute is defined.
bool isDef = Attribute.IsDefined(
paramInfo, typeof(ParamArrayAttribute));
if( isDef )
Console.WriteLine(
"\nThe ParamArray attribute is defined " +
"for \nparameter {0} of method {1}.",
paramInfo.Name, mInfo.Name);
// See if ParamUsageAttribute is defined.
// If so, display a message.
ArgumentUsageAttribute usageAttr = (ArgumentUsageAttribute)
Attribute.GetCustomAttribute(
paramInfo, typeof(ArgumentUsageAttribute) );
if( usageAttr != null )
{
Console.WriteLine(
"\nThe ArgumentUsage attribute is defined " +
"for \nparameter {0} of method {1}.",
paramInfo.Name, mInfo.Name );
Console.WriteLine( "\n The usage " +
"message for {0} is:\n \"{1}\".",
paramInfo.Name, usageAttr.Message);
}
}
}
else
Console.WriteLine(
"The parameters information could not " +
"be retrieved for method {0}.", mInfo.Name);
}
}
}
/*
This example of Attribute.GetCustomAttribute( ParameterInfo, Type )
generates the following output.
The ArgumentUsage attribute is defined for
parameter strArray of method TestMethod.
The usage message for strArray is:
"Must pass an array here.".
The ParamArray attribute is defined for
parameter strList of method TestMethod.
The ArgumentUsage attribute is defined for
parameter strList of method TestMethod.
The usage message for strList is:
"Can pass a parameter list or array here.".
*/
open System
open System.Reflection
// Define a custom parameter attribute that takes a single message argument.
[<AttributeUsage(AttributeTargets.Parameter); AllowNullLiteral>]
type ArgumentUsageAttribute(usageMsg) =
inherit Attribute()
// This is the Message property for the attribute.
member val Message = usageMsg with get, set
type BaseClass() =
// Assign an ArgumentUsage attribute to the strArray parameter.
// Assign a ParamArray attribute to strList.
abstract member TestMethod: strArray: string[] * strList: string[] -> unit
default _.TestMethod([<ArgumentUsage("Must pass an array here.")>] strArray, [<ParamArray>] strList) = ()
type DerivedClass() =
inherit BaseClass()
// Assign an ArgumentUsage attribute to the strList parameter.
// Assign a ParamArray attribute to strList.
override _.TestMethod(
strArray,
[<ArgumentUsage "Can pass a parameter list or array here."; ParamArray>]
strList) = ()
printfn "This example of Attribute.GetCustomAttribute( ParameterInfo, Type )\ngenerates the following output."
// Get the class type, and then get the MethodInfo object
// for TestMethod to access its metadata.
let clsType = typeof<DerivedClass>
let mInfo = clsType.GetMethod "TestMethod"
// Iterate through the ParameterInfo array for the method parameters.
let pInfoArray = mInfo.GetParameters()
if pInfoArray <> null then
for paramInfo in pInfoArray do
// See if the ParamArray attribute is defined.
let isDef = Attribute.IsDefined(paramInfo, typeof<ParamArrayAttribute>)
if isDef then
printfn $"\nThe ParamArray attribute is defined for \nparameter {paramInfo.Name} of method {mInfo.Name}."
// See if ParamUsageAttribute is defined.
// If so, display a message.
let usageAttr =
Attribute.GetCustomAttribute(paramInfo, typeof<ArgumentUsageAttribute>)
:?> ArgumentUsageAttribute
if usageAttr <> null then
printfn $"\nThe ArgumentUsage attribute is defined for \nparameter {paramInfo.Name} of method {mInfo.Name}."
printfn $"\n The usage message for {paramInfo.Name} is:\n \"{usageAttr.Message}\"."
else
printfn $"The parameters information could not be retrieved for method {mInfo.Name}."
// This example of Attribute.GetCustomAttribute(ParameterInfo, Type)
// generates the following output:
// The ArgumentUsage attribute is defined for
// parameter strArray of method TestMethod.
//
// The usage message for strArray is:
// "Must pass an array here.".
//
// The ParamArray attribute is defined for
// parameter strList of method TestMethod.
//
// The ArgumentUsage attribute is defined for
// parameter strList of method TestMethod.
//
// The usage message for strList is:
// "Can pass a parameter list or array here.".
' Example for the Attribute.GetCustomAttribute( ParameterInfo, Type ) method.
Imports System.Reflection
Namespace NDP_UE_VB
' Define a custom parameter attribute that takes a single message argument.
<AttributeUsage(AttributeTargets.Parameter)> _
Public Class ArgumentUsageAttribute
Inherits Attribute
' This is the attribute constructor.
Public Sub New(UsageMsg As String)
Me.usageMsg = UsageMsg
End Sub
' usageMsg is storage for the attribute message.
Protected usageMsg As String
' This is the Message property for the attribute.
Public Property Message() As String
Get
Return usageMsg
End Get
Set
usageMsg = value
End Set
End Property
End Class
Public Class BaseClass
' Assign an ArgumentUsage attribute to the strArray parameter.
' Assign a ParamArray attribute to strList using the ParamArray keyword.
Public Overridable Sub TestMethod( _
<ArgumentUsage("Must pass an array here.")> _
strArray() As String, _
ParamArray strList() As String)
End Sub
End Class
Public Class DerivedClass
Inherits BaseClass
' Assign an ArgumentUsage attribute to the strList parameter.
' Assign a ParamArray attribute to strList using the ParamArray keyword.
Public Overrides Sub TestMethod( _
strArray() As String, _
<ArgumentUsage("Can pass a parameter list or array here.")> _
ParamArray strList() As String)
End Sub
End Class
Module CustomParamDemo
Sub Main()
Console.WriteLine( _
"This example of Attribute.GetCustomAttribute" & _
"( ParameterInfo, Type )" & vbCrLf & _
"generates the following output.")
' Get the class type, and then get the MethodInfo object
' for TestMethod to access its metadata.
Dim clsType As Type = GetType(DerivedClass)
Dim mInfo As MethodInfo = clsType.GetMethod("TestMethod")
' Iterate through the ParameterInfo array for the method parameters.
Dim pInfoArray As ParameterInfo() = mInfo.GetParameters()
If Not (pInfoArray Is Nothing) Then
Dim paramInfo As ParameterInfo
For Each paramInfo In pInfoArray
' See if the ParamArray attribute is defined.
Dim isDef As Boolean = _
Attribute.IsDefined(paramInfo, _
GetType(ParamArrayAttribute))
If isDef Then
Console.WriteLine( vbCrLf & _
"The ParamArray attribute is defined for " & _
vbCrLf & "parameter {0} of method {1}.", _
paramInfo.Name, mInfo.Name)
End If
' See if ParamUsageAttribute is defined.
' If so, display a message.
Dim usageAttr As ArgumentUsageAttribute = _
Attribute.GetCustomAttribute(paramInfo, _
GetType(ArgumentUsageAttribute))
If Not (usageAttr Is Nothing) Then
Console.WriteLine( vbCrLf & "The " & _
"ArgumentUsage attribute is defined for " & _
vbCrLf & "parameter {0} of method {1}.", _
paramInfo.Name, mInfo.Name)
Console.WriteLine( vbCrLf & _
" The usage message for {0} is: " & _
vbCrLf & " ""{1}"".", _
paramInfo.Name, usageAttr.Message)
End If
Next paramInfo
Else
Console.WriteLine( _
"The parameters information could " & _
"not be retrieved for method {0}.", mInfo.Name)
End If
End Sub
End Module ' DemoClass
End Namespace ' NDP_UE_VB
' This example of Attribute.GetCustomAttribute( ParameterInfo, Type )
' generates the following output.
'
' The ArgumentUsage attribute is defined for
' parameter strArray of method TestMethod.
'
' The usage message for strArray is:
' "Must pass an array here.".
'
' The ParamArray attribute is defined for
' parameter strList of method TestMethod.
'
' The ArgumentUsage attribute is defined for
' parameter strList of method TestMethod.
'
' The usage message for strList is:
' "Can pass a parameter list or array here.".
注解
如果 element 表示派生类型的方法中的参数，则返回值包括应用于重写基方法中相同参数的可继承自定义属性。
适用于
.NET 7 和其他版本
| 产品 | 版本 |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| .NET Standard | 2.0, 2.1 |