MemberInfo.IsDefined(Type, Boolean) Metode

Definisi

Ruang nama:

System.Reflection

Rakitan:

System.Runtime.dll

Sumber:

MemberInfo.cs

Ketika ditimpa di kelas turunan, menunjukkan apakah satu atau beberapa atribut dari jenis yang ditentukan atau jenis turunannya diterapkan kepada anggota ini.

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

Parameter

attributeType

Type

Jenis atribut kustom yang akan dicari. Pencarian mencakup jenis turunan.

inherit

Boolean

true untuk mencari rantai warisan anggota ini untuk menemukan atribut; jika tidak, false. Parameter ini diabaikan untuk properti dan peristiwa.

Mengembalikan

Boolean

true jika satu atau beberapa instans attributeType atau salah satu jenis turunannya diterapkan pada anggota ini; jika tidak, false.

Penerapan

IsDefined(Type, Boolean)

Contoh

Contoh berikut menentukan apakah atribut yang ditentukan diterapkan ke anggota yang ditentukan.

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.Reflection

' 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

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

' 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
End Class

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
End Class

Keterangan

Metode ini mengabaikan inherit parameter untuk properti dan peristiwa. Untuk mencari rantai pewarisan untuk atribut pada properti dan peristiwa, gunakan kelebihan beban metode yang Attribute.IsDefined sesuai.

Catatan

Dalam .NET Framework versi 2.0, metode ini mengembalikan true jika jenis, metode, atau konstruktor memiliki atribut keamanan yang disimpan dalam format metadata baru. Rakitan yang dikompilasi dengan versi 2.0 menggunakan format ini. Rakitan dan rakitan dinamis yang dikompilasi dengan versi .NET Framework sebelumnya menggunakan format XML lama. Lihat Memancarkan Atribut Keamanan Deklaratif.