CustomAttributeBuilder 類別

定義

命名空間:

System.Reflection.Emit

組件:

System.Reflection.Emit.ILGeneration.dll

來源:

CustomAttributeBuilder.cs

協助建立自訂屬性 (Attribute)。

C#

public class CustomAttributeBuilder

繼承

Object

CustomAttributeBuilder

範例

下列程式代碼範例說明 如何使用 CustomAttributeBuilder。

C#

using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;

// We will apply this custom attribute to our dynamic type.
public class ClassCreator: Attribute

{
   private string creator;
   public string Creator
   {
    get
    {
       return creator;
    }
   }	

   public ClassCreator(string name)
   {
      this.creator = name;
   }
}

// We will apply this dynamic attribute to our dynamic method.
public class DateLastUpdated: Attribute

{
   private string dateUpdated;
   public string DateUpdated
   {
    get
    {
       return dateUpdated;
    }
   }

   public DateLastUpdated(string theDate)
   {
    this.dateUpdated = theDate;
   }
}

class MethodBuilderCustomAttributesDemo

{

   public static Type BuildTypeWithCustomAttributesOnMethod()
   {
    
    AppDomain currentDomain = Thread.GetDomain();
    
    AssemblyName myAsmName = new AssemblyName();
    myAsmName.Name = "MyAssembly";

    AssemblyBuilder myAsmBuilder = currentDomain.DefineDynamicAssembly(
                       myAsmName, AssemblyBuilderAccess.Run);

    ModuleBuilder myModBuilder = myAsmBuilder.DefineDynamicModule("MyModule");

    // First, we'll build a type with a custom attribute attached.

    TypeBuilder myTypeBuilder = myModBuilder.DefineType("MyType",
                        TypeAttributes.Public);
    
    Type[] ctorParams = new Type[] { typeof(string) };
    ConstructorInfo classCtorInfo = typeof(ClassCreator).GetConstructor(ctorParams);

    CustomAttributeBuilder myCABuilder = new CustomAttributeBuilder(
                        classCtorInfo,
                        new object[] { "Joe Programmer" });

    myTypeBuilder.SetCustomAttribute(myCABuilder);

    // Now, let's build a method and add a custom attribute to it.

    MethodBuilder myMethodBuilder = myTypeBuilder.DefineMethod("HelloWorld",
                    MethodAttributes.Public,
                    null,
                    new Type[] { });

    ctorParams = new Type[] { typeof(string) };
    classCtorInfo = typeof(DateLastUpdated).GetConstructor(ctorParams);

    CustomAttributeBuilder myCABuilder2 = new CustomAttributeBuilder(
                        classCtorInfo,
                        new object[] { DateTime.Now.ToString() });

    myMethodBuilder.SetCustomAttribute(myCABuilder2);

    ILGenerator myIL = myMethodBuilder.GetILGenerator();

    myIL.EmitWriteLine("Hello, world!");
    myIL.Emit(OpCodes.Ret);

    return myTypeBuilder.CreateType();
   }

   public static void Main()
   {

    Type myType = BuildTypeWithCustomAttributesOnMethod();

    object myInstance = Activator.CreateInstance(myType);

    object[] customAttrs = myType.GetCustomAttributes(true);

    Console.WriteLine("Custom Attributes for Type 'MyType':");

    object attrVal = null;

    foreach (object customAttr in customAttrs)
    {
       attrVal = typeof(ClassCreator).InvokeMember("Creator",
                      BindingFlags.GetProperty,
                      null, customAttr, new object[] { });
       Console.WriteLine("-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal);
        }

    Console.WriteLine("Custom Attributes for Method 'HelloWorld()' in 'MyType':");

    customAttrs = myType.GetMember("HelloWorld")[0].GetCustomAttributes(true);	

    foreach (object customAttr in customAttrs)
    {
       attrVal = typeof(DateLastUpdated).InvokeMember("DateUpdated",
                      BindingFlags.GetProperty,
                      null, customAttr, new object[] { });
       Console.WriteLine("-- Attribute: [{0} = \"{1}\"]", customAttr, attrVal);
        }

    Console.WriteLine("---");

    Console.WriteLine(myType.InvokeMember("HelloWorld",
              BindingFlags.InvokeMethod,
              null, myInstance, new object[] { }));
   }
}

備註

使用建 CustomAttributeBuilder 構函式傳回的物件來描述自定義屬性。 CustomAttribute藉由在該產生器實例上呼叫 方法，將 SetCustomAttribute 與產生器實例產生關聯。 例如，藉由提供的建構函式及其自變數，建立 來CustomAttributeBuilder描述的AssemblyCultureAttribute實例AssemblyCultureAttribute。 然後呼叫 SetCustomAttribute 以 AssemblyBuilder 建立關聯。

建構函式

CustomAttributeBuilder(ConstructorInfo, Object[])	指定自訂屬性的建構函式與建構函式的引數，初始化 CustomAttributeBuilder 類別的執行個體。
CustomAttributeBuilder(ConstructorInfo, Object[], FieldInfo[], Object[])	初始化 CustomAttributeBuilder 類別的執行個體，該類別指定了自訂屬性的建構函式、建構函式的引數，以及一組命名的欄位/值配對。
CustomAttributeBuilder(ConstructorInfo, Object[], PropertyInfo[], Object[])	初始化 CustomAttributeBuilder 類別的執行個體，該類別指定了自訂屬性的建構函式、建構函式的引數，以及一組命名的屬性或值配對。
CustomAttributeBuilder(ConstructorInfo, Object[], PropertyInfo[], Object[], FieldInfo[], Object[])	初始化 CustomAttributeBuilder 類別的執行個體，該類別指定了自訂屬性的建構函式、建構函式的引數、一組命名的屬性或值配對，以及一組命名的欄位或值配對。

方法

Equals(Object)	判斷指定的物件是否等於目前的物件。 (繼承來源 Object)
GetHashCode()	做為預設雜湊函式。 (繼承來源 Object)
GetType()	取得目前執行個體的 Type。 (繼承來源 Object)
MemberwiseClone()	建立目前 Object 的淺層複製。 (繼承來源 Object)
ToString()	傳回代表目前物件的字串。 (繼承來源 Object)

適用於