檢視型別資訊

發行項
08/21/2008

更新：2007 年 11 月

System.Type 類別為反映的核心。當反映要求時，Common Language Runtime 會為載入的型別建立 Type。您可以使用 Type 物件的方法、欄位、屬性和巢狀類別，找出該型別的一切事項。

使用 Assembly.GetType 或 Assembly.GetTypes，可以從尚未載入的組件取得 Type 物件，傳入型別名稱或您所需的型別。使用 Type.GetType 可以從已載入的組件取得 Type 物件。使用 Module.GetType 和 Module.GetTypes 可取得模組 Type 物件。

注意事項：
如果您想要檢視和使用泛型型別和方法，請參閱反映和泛型型別和 HOW TO：使用反映檢視和執行個體化泛型型別中提供的其他資訊。

下列範例說明取得 Assembly 物件和組件模組的必要語法。

' Gets the mscorlib assembly in which the object is defined.
Dim a As Reflection.Assembly = GetType(Object).Module.Assembly

// Gets the mscorlib assembly in which the object is defined.
Assembly a = typeof(Object).Module.Assembly;

下列範例示範從載入的組件取得 Type 物件。

' Loads an assembly using its file name.
Dim a As Reflection.Assembly = Reflection.Assembly.LoadFrom("MyExe.exe")
' Gets the type names from the assembly.
Dim types2 As Type() = a.GetTypes()
Dim t As Type
For Each t In  types2
    Console.WriteLine(t.FullName)
Next t

// Loads an assembly using its file name.
Assembly a = Assembly.LoadFrom ("MyExe.exe");
// Gets the type names from the assembly.
Type [] types2 = a.GetTypes ();
foreach (Type t in types2)
{
    Console.WriteLine (t.FullName);
}

一旦您取得 Type，有許多方式可供您尋找關於該型別成員的資訊。例如，您可以呼叫 Type.GetMembers 方法，取得描述目前型別每一個成員的 MemberInfo 物件陣列，以找出型別的所有成員。

您也可以使用 Type 類別上的方法，擷取一個或多個您按名稱指定的建構函式、方法、事件、欄位或屬性的資訊。例如，Type.GetConstructor 會封裝目前類別的特定建構函式。

如果有 Type，便可以使用 Type.Module 屬性，取得封裝含有該型別模組的物件。使用 Module.Assembly 屬性，找出封裝含有模組組件的物件。您可以取得組件，使用 Type.Assembly 屬性直接封裝型別。

System.Type 和 ConstructorInfo

下列程式碼範例說明如何列出類別的建構函式，在此例中為 String 類別。

' This program lists all the public constructors 
' of the System.String class.
Imports System
Imports System.Reflection
Class ListMembers
    Public Shared Sub Main()
        Dim t As Type = GetType(String)
        Console.WriteLine("Listing all the public constructors of the {0} type", t)
        ' Constructors.
        Dim ci As ConstructorInfo() = t.GetConstructors((BindingFlags.Public Or BindingFlags.Instance))
        Console.WriteLine("//Constructors")
        PrintMembers(ci)
    End Sub
    Public Shared Sub PrintMembers(ms() As MemberInfo)
        Dim m As MemberInfo
        For Each m In ms
            Console.WriteLine("{0}{1}", "     ", m)
        Next m
        Console.WriteLine()
    End Sub
End Class

// This program lists all the public constructors 
// of the System.String class.
using System;
using System.Reflection;
class ListMembers {
    public static void Main(String[] args) {
        Type t = typeof(System.String);
        Console.WriteLine ("Listing all the public constructors of the {0} type", t);
        // Constructors.
        ConstructorInfo[] ci = t.GetConstructors(BindingFlags.Public | BindingFlags.Instance);
        Console.WriteLine ("//Constructors");
        PrintMembers (ci);
    }
    public static void PrintMembers(MemberInfo [] ms) {
        foreach (MemberInfo m in ms) {
            Console.WriteLine ("{0}{1}", "     ", m);
        }
        Console.WriteLine();
    }
}

MemberInfo、MethodInfo、FieldInfo 和 PropertyInfo

使用 MemberInfo、MethodInfo、FieldInfo 或 PropertyInfo 物件，取得型別的方法、屬性、事件和欄位的資訊。

下列範例使用 MemberInfo 列出 System.IO.File 類別中成員的數目，並使用 System.Type.IsPublic 屬性判斷類別的可視性。

Option Explicit
Option Strict
Imports System
Imports System.IO
Imports System.Reflection
Imports Microsoft.VisualBasic
Class Mymemberinfo
    Public Shared Sub Main()
        Console.WriteLine(ControlChars.Cr & "Reflection.MemberInfo")
        ' Gets the Type and MemberInfo.
        Dim MyType As Type = Type.GetType("System.IO.File")
        Dim Mymemberinfoarray As MemberInfo() = MyType.GetMembers()
        ' Gets and displays the DeclaringType method. 
        Console.WriteLine(ControlChars.Cr & "There are {0} members in {1}.", Mymemberinfoarray.Length, MyType.FullName)
        Console.WriteLine("{0}.", MyType.FullName)
        If MyType.IsPublic Then
            Console.WriteLine("{0} is public.", MyType.FullName)
        End If
    End Sub
End Class

using System;
using System.IO;
using System.Reflection;

class Mymemberinfo
{ 
    public static void Main(string[] args)
    { 
        Console.WriteLine ("\nReflection.MemberInfo");
        // Gets the Type and MemberInfo.
        Type MyType =Type.GetType("System.IO.File");
        MemberInfo[] Mymemberinfoarray = MyType.GetMembers(); 
        // Gets and displays the DeclaringType method. 
        Console.WriteLine("\nThere are {0} members in {1}.", 
            Mymemberinfoarray.Length, MyType.FullName);
        Console.WriteLine("{0}.", MyType.FullName); 
        if (MyType.IsPublic)
        {
            Console.WriteLine("{0} is public.", MyType.FullName);
        }
    }
}

下列範例檢查指定成員的型別。它執行 MemberInfo 類別成員上的反映，並列出它的型別。

' This code displays information about the GetValue method of FieldInfo.
Option Explicit
Option Strict
Imports System
Imports System.Reflection
Class MyMethodInfo
    Public Shared Sub Main()
        Console.WriteLine("Reflection.MethodInfo")
        ' Gets and displays the Type.
        Dim MyType As Type = Type.GetType("System.Reflection.FieldInfo")
        ' Specifies the member for which you want type information.
        Dim Mymethodinfo As MethodInfo = MyType.GetMethod("GetValue")
        Console.WriteLine((MyType.FullName & "." & Mymethodinfo.Name))
        ' Gets and displays the MemberType property.
        Dim Mymembertypes As MemberTypes = Mymethodinfo.MemberType
        If MemberTypes.Constructor = Mymembertypes Then
            Console.WriteLine("MemberType is of type All")
        ElseIf MemberTypes.Custom = Mymembertypes Then
            Console.WriteLine("MemberType is of type Custom")
        ElseIf MemberTypes.Event = Mymembertypes Then
            Console.WriteLine("MemberType is of type Event")
        ElseIf MemberTypes.Field = Mymembertypes Then
            Console.WriteLine("MemberType is of type Field")
        ElseIf MemberTypes.Method = Mymembertypes Then
            Console.WriteLine("MemberType is of type Method")
        ElseIf MemberTypes.Property = Mymembertypes Then
            Console.WriteLine("MemberType is of type Property")
        ElseIf MemberTypes.TypeInfo = Mymembertypes Then
            Console.WriteLine("MemberType is of type TypeInfo")
        End If
        Return
    End Sub
End Class

// This code displays information about the GetValue method of FieldInfo.
using System;
using System.Reflection;
class MyMethodInfo {
    public static int Main() {
        Console.WriteLine("Reflection.MethodInfo");
        // Gets and displays the Type.
        Type MyType = Type.GetType("System.Reflection.FieldInfo");
        // Specifies the member for which you want type information.
        MethodInfo Mymethodinfo = MyType.GetMethod("GetValue");
        Console.WriteLine(MyType.FullName + "." + Mymethodinfo.Name);
        // Gets and displays the MemberType property.
        MemberTypes Mymembertypes = Mymethodinfo.MemberType;
        if (MemberTypes.Constructor == Mymembertypes) {
            Console.WriteLine("MemberType is of type All"); 
        }
        else if (MemberTypes.Custom == Mymembertypes) {
            Console.WriteLine("MemberType is of type Custom"); 
        }
        else if (MemberTypes.Event == Mymembertypes) {
            Console.WriteLine("MemberType is of type Event"); 
        }
        else if (MemberTypes.Field == Mymembertypes) {
            Console.WriteLine("MemberType is of type Field"); 
        }
        else if (MemberTypes.Method == Mymembertypes) {
            Console.WriteLine("MemberType is of type Method"); 
        }
        else if (MemberTypes.Property == Mymembertypes) {
            Console.WriteLine("MemberType is of type Property"); 
        }
        else if (MemberTypes.TypeInfo == Mymembertypes) {
            Console.WriteLine("MemberType is of type TypeInfo"); 
        }
        return 0;
    }
}

下列程式碼範例使用所有的 Reflection *Info 類別，連同 BindingFlags，列出指定類別的所有成員 (建構函式、欄位、屬性、事件和方法)，並將成員區分為靜態和執行個體分類。

' This program lists all the members of the 
' System.IO.BufferedStream class.
Imports System
Imports System.IO
Imports System.Reflection
Imports Microsoft.VisualBasic
Class ListMembers
    Public Shared Sub Main()
        ' Specifies the class.
        Dim t As Type = GetType(System.IO.BufferedStream)
        Console.WriteLine("Listing all the members (public and non public) of the {0} type", t)
        ' Lists static fields first.
        Dim fi As FieldInfo() = t.GetFields((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Fields")
        PrintMembers(fi)
        ' Static properties.
        Dim pi As PropertyInfo() = t.GetProperties((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Properties")
        PrintMembers(pi)
        ' Static events.
        Dim ei As EventInfo() = t.GetEvents((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Events")
        PrintMembers(ei)
        ' Static methods.
        Dim mi As MethodInfo() = t.GetMethods((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Methods")
        PrintMembers(mi)
        ' Constructors.
        Dim ci As ConstructorInfo() = t.GetConstructors((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Constructors")
        PrintMembers(ci)
        ' Instance fields.
        fi = t.GetFields((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Fields")
        PrintMembers(fi)
        ' Instance properites.
        pi = t.GetProperties((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Properties")
        PrintMembers(pi)
        ' Instance events.
        ei = t.GetEvents((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Events")
        PrintMembers(ei)
        ' Instance methods.
        mi = t.GetMethods((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Methods")
        PrintMembers(mi)
        Console.WriteLine(ControlChars.CrLf & "Press ENTER to exit.")
        Console.Read()
    End Sub
    Public Shared Sub PrintMembers(ms() As MemberInfo)
        Dim m As MemberInfo
        For Each m In  ms
            Console.WriteLine("{0}{1}", "     ", m)
        Next m
        Console.WriteLine()
    End Sub
End Class

// This program lists all the members of the 
// System.IO.BufferedStream class.
using System;
using System.IO;
using System.Reflection;

class ListMembers {
    public static void Main(String[] args) {
        // Specifies the class.
        Type t = typeof (System.IO.BufferedStream);
        Console.WriteLine ("Listing all the members (public and non public) of the {0} type", t);

        // Lists static fields first.
        FieldInfo [] fi = t.GetFields (BindingFlags.Static | 
         BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine ("// Static Fields");
        PrintMembers (fi);

        // Static properties.
        PropertyInfo [] pi = t.GetProperties (BindingFlags.Static | 
         BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine ("// Static Properties");
        PrintMembers (pi);

        // Static events.
        EventInfo [] ei = t.GetEvents (BindingFlags.Static | 
         BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine ("// Static Events");
        PrintMembers (ei);

        // Static methods.
        MethodInfo [] mi = t.GetMethods (BindingFlags.Static | 
         BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine ("// Static Methods");
        PrintMembers (mi);

        // Constructors.
        ConstructorInfo [] ci = t.GetConstructors (BindingFlags.Instance | 
         BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine ("// Constructors");
        PrintMembers (ci);

        // Instance fields.
        fi = t.GetFields (BindingFlags.Instance | BindingFlags.NonPublic | 
         BindingFlags.Public);
        Console.WriteLine ("// Instance Fields");
        PrintMembers (fi);

        // Instance properites.
        pi = t.GetProperties (BindingFlags.Instance | BindingFlags.NonPublic | 
         BindingFlags.Public);
        Console.WriteLine ("// Instance Properties");
        PrintMembers (pi);

        // Instance events.
        ei = t.GetEvents (BindingFlags.Instance | BindingFlags.NonPublic | 
         BindingFlags.Public);
        Console.WriteLine ("// Instance Events");
        PrintMembers (ei);

        // Instance methods.
        mi = t.GetMethods (BindingFlags.Instance | BindingFlags.NonPublic   
         | BindingFlags.Public);
        Console.WriteLine ("// Instance Methods");
        PrintMembers (mi);

        Console.WriteLine ("\r\nPress ENTER to exit.");
        Console.Read();
    }

    public static void PrintMembers (MemberInfo [] ms) {
        foreach (MemberInfo m in ms) {
            Console.WriteLine ("{0}{1}", "     ", m);
        }
        Console.WriteLine();
    }
}