MemberInfo.IsDefined(Type, Boolean) MemberInfo.IsDefined(Type, Boolean) MemberInfo.IsDefined(Type, Boolean) MemberInfo.IsDefined(Type, Boolean) Method

定义

在派生类中重写时,指示是否将指定类型或其派生类型的一个或多个特性应用于此成员。When overridden in a derived class, indicates whether one or more attributes of the specified type or of its derived types is applied to this member.

public:
 abstract bool IsDefined(Type ^ attributeType, bool inherit);
public abstract bool IsDefined (Type attributeType, bool inherit);
abstract member IsDefined : Type * bool -> bool
Public MustOverride Function IsDefined (attributeType As Type, inherit As Boolean) As Boolean

参数

attributeType
Type Type Type Type

要搜索的自定义属性的类型。The type of custom attribute to search for. 该搜索包括派生类型。The search includes derived types.

inherit
Boolean Boolean Boolean Boolean

如果要搜索此成员的继承链以查找属性,则为 true;否则为 falsetrue to search this member's inheritance chain to find the attributes; otherwise, false. 会忽略属性和事件的此参数。This parameter is ignored for properties and events.

返回

如果将 attributeType 或其任何派生类型的一个或多个实例应用于此成员,则为 true;否则为 falsetrue if one or more instances of attributeType or any of its derived types is applied to this member; otherwise, false.

实现

示例

下面的示例确定是否将指定的特性应用于指定的成员。The following example determines whether the specified attribute is applied to the specified member.

using namespace System;
using namespace System::Reflection;

// Define a custom attribute with one named parameter.

[AttributeUsage(AttributeTargets::All)]
public ref class MyAttribute: public Attribute
{
private:
   String^ myName;

public:
   MyAttribute( String^ name )
   {
      myName = name;
   }

   property String^ Name 
   {
      String^ get()
      {
         return myName;
      }
   }
};

// Define a class that has the custom attribute associated with one of its members.
public ref class MyClass1
{
public:

   [MyAttribute("This is an example attribute.")]
   void MyMethod( int i ){}
};

int main()
{
   try
   {
      // Get the type of MyClass1.
      Type^ myType = MyClass1::typeid;

      // Get the members associated with MyClass1.
      array<MemberInfo^>^myMembers = myType->GetMembers();

      // Display the attributes for each of the members of MyClass1.
      for ( int i = 0; i < myMembers->Length; i++ )
      {
         // Display the attribute if it is of type MyAttribute.
         if ( myMembers[ i ]->IsDefined( MyAttribute::typeid, false ) )
         {
            array<Object^>^myAttributes = myMembers[ i ]->GetCustomAttributes( MyAttribute::typeid, false );
            Console::WriteLine( "\nThe attributes of type MyAttribute for the member {0} are: \n", myMembers[ i ] );
            for ( int j = 0; j < myAttributes->Length; j++ )

               // Display the value associated with the attribute.
               Console::WriteLine( "The value of the attribute is : \"{0}\"",
                        (safe_cast<MyAttribute^>(myAttributes[ j ]))->Name );
         }
      }
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "An exception occurred: {0}", e->Message );
   }
}

using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets.All)]
public class MyAttribute : Attribute
{
    private string myName;
    public MyAttribute(string name)
    {
        myName = name;
    }
    public string Name
    {
        get
        {
            return myName;
        }
    }
}

// Define a class that has the custom attribute associated with one of its members.
public class MyClass1
{
    [MyAttribute("This is an example attribute.")]
    public void MyMethod(int i)
    {
        return;
    }
}

public class MemberInfo_GetCustomAttributes_IsDefined
{
    public static void Main()
    {
        try
        {
            // Get the type of MyClass1.
            Type myType = typeof(MyClass1);
            // Get the members associated with MyClass1.
            MemberInfo[] myMembers = myType.GetMembers();

            // Display the attributes for each of the members of MyClass1.
            for(int i = 0; i < myMembers.Length; i++)
            {
                // Display the attribute if it is of type MyAttribute.
                if(myMembers[i].IsDefined(typeof(MyAttribute), false))
                {
                    Object[] myAttributes = myMembers[i].GetCustomAttributes(typeof(MyAttribute), false);
                    Console.WriteLine("\nThe attributes of type MyAttribute for the member {0} are: \n",
                        myMembers[i]);
                    for(int j = 0; j < myAttributes.Length; j++)
                        // Display the value associated with the attribute.
                        Console.WriteLine("The value of the attribute is : \"{0}\"",
                            ((MyAttribute)myAttributes[j]).Name);
                }
            }
        }
        catch(Exception e)
        {
            Console.WriteLine("An exception occurred: {0}", e.Message);
        }
    }
}
Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

' Define a custom attribute with one named parameter.
<AttributeUsage(AttributeTargets.All)> Public Class MyAttribute
    Inherits Attribute
    Private myName As String

    Public Sub New(ByVal name As String)
        myName = name
    End Sub 'New

    Public ReadOnly Property Name() As String
        Get
            Return myName
        End Get
    End Property
End Class 'MyAttribute

' Define a class that has the custom attribute associated with one of its members.
Public Class MyClass1

    <MyAttribute("This is an example attribute.")> Public Sub MyMethod(ByVal i As Integer)
        Return
    End Sub 'MyMethod
End Class 'MyClass1

Public Class MemberInfo_GetCustomAttributes_IsDefined

    Public Shared Sub Main()
        Try
            ' Get the type of MyClass1.
            Dim myType As Type = GetType(MyClass1)
            ' Get the members associated with MyClass1.
            Dim myMembers As MemberInfo() = myType.GetMembers()

            ' Display the attributes for each of the members of MyClass1.
            Dim i As Integer
            For i = 0 To myMembers.Length - 1
                ' Display the attribute if it is of type MyAttribute.
                If myMembers(i).IsDefined(GetType(MyAttribute), False) Then
                    Dim myAttributes As [Object]() = myMembers(i).GetCustomAttributes(GetType(MyAttribute), False)
                    Console.WriteLine(ControlChars.Cr + "The attributes of type MyAttribute for the member {0} are: " + ControlChars.Cr, myMembers(i))
                    Dim j As Integer
                    For j = 0 To myAttributes.Length - 1
                        ' Display the value associated with the attribute.
                        Console.WriteLine("The value of the attribute is : ""{0}""", CType(myAttributes(j), MyAttribute).Name)
                    Next j
                End If
            Next i
        Catch e As Exception
            Console.WriteLine("An exception occurred: {0}", e.Message)
        End Try
    End Sub 'Main
End Class 'MemberInfo_GetCustomAttributes_IsDefined

注解

此方法会忽略inherit属性和事件的参数。This method ignores the inherit parameter for properties and events. 若要搜索的属性和事件属性的继承链,使用的适当重载Attribute.IsDefined方法。To search the inheritance chain for attributes on properties and events, use the appropriate overloads of the Attribute.IsDefined method.

备注

在.NET Framework 2.0 版中,此方法返回true类型、 方法或构造函数具有新的元数据格式存储的安全属性。In the .NET Framework version 2.0, this method returns true if a type, method, or constructor has security attributes stored in the new metadata format. 使用版本 2.0 编译的程序集使用此格式。Assemblies compiled with version 2.0 use this format. 动态程序集和与早期版本的.NET Framework 编译的程序集使用旧的 XML 格式。Dynamic assemblies and assemblies compiled with earlier versions of the .NET Framework use the old XML format. 请参阅发出的声明性安全特性See Emitting Declarative Security Attributes.

适用于