MulticastDelegate MulticastDelegate MulticastDelegate MulticastDelegate Class

定义

表示多路广播委托;即,其调用列表中可以拥有多个元素的委托。Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.

public ref class MulticastDelegate abstract : Delegate
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public abstract class MulticastDelegate : Delegate
type MulticastDelegate = class
    inherit Delegate
Public MustInherit Class MulticastDelegate
Inherits Delegate
继承
MulticastDelegateMulticastDelegateMulticastDelegateMulticastDelegate
属性

示例

下面的示例定义了一个类StringContainer,其中包括字符串的集合。The following example defines a class, StringContainer, which includes a collection of strings. 其成员之一是CheckAndDisplayDelegate委托,用于显示字符串存储在StringContainer满足特定条件的对象。One of its members is the CheckAndDisplayDelegate delegate, which is used to display strings stored in a StringContainer object that satisfy particular criteria. 委托采用单个字符串用作参数并返回void(或在 Visual Basic 中,它是Sub过程)。The delegate takes a single string as a parameter and returns void (or, in Visual Basic, it's a Sub procedure). 它还包括一种方法, DisplayAllQualified,它具有单个参数,CheckAndDisplayDelegate委托。It also includes a method, DisplayAllQualified, that has a single parameter, a CheckAndDisplayDelegate delegate. 这样,要调用的方法和显示的字符串进行筛选后的一组基于包含该委托的方法。This allows the method to be called and to display a set of strings that are filtered based on the methods that the delegate contains.

该示例还定义了一个实用工具类StringExtensions,有两种方法:The example also defines a utility class, StringExtensions, that has two methods:

  • ConStart其中显示以辅音字母开头的字符串。ConStart, which displays strings that begin with a consonant.

  • VowelStart其中显示元音开头的字符串。VowelStart, which displays strings that begin with a vowel.

请注意,这两种方法包括单个字符串参数和返回voidNote that both methods include a single string parameter and return void. 换而言之,这两种方法可以分配给CheckAndDisplayDelegate委托。In other words, both methods can be assigned to the CheckAndDisplayDelegate delegate.

Test.Main方法是应用程序入口点。The Test.Main method is the application entry point. 它实例化StringContainer对象,其中填充字符串,并创建两个CheckAndDisplayDelegate委托conStartvowelStart,调用单个方法。It instantiates a StringContainer object, populates it with strings, and creates two CheckAndDisplayDelegate delegates, conStart and vowelStart, that invoke a single method. 然后,它调用Delegate.Combine方法来创建multipleDelegates委托,它最初包含ConStartVowelStart委托。It then calls the Delegate.Combine method to create the multipleDelegates delegate, which initially contains the ConStart and VowelStart delegates. 请注意,当multipleDelegates调用委托时,它显示按原始顺序集合中的所有字符串。Note that when the multipleDelegates delegate is invoked, it displays all the strings in the collection in their original order. 这是因为每个字母被单独传递到每个委托,并且每个字母满足筛选条件的两个委托之一。This is because each letter is passed separately to each delegate, and each letter meets the filtering criteria of only one of the two delegates. 最后之后调用,Delegate.RemoveDelegate.CombinemultipleDelegates包含两个conStart委托。Finally, after calls to Delegate.Remove and Delegate.Combine, multipleDelegates contains two conStart delegates. 调用时,在每个字符串StringContainer对象显示两次。When it is invoked, each string in the StringContainer object is displayed twice.

using namespace System;
using namespace System::Collections::Generic;

ref class StringContainer
{
private:
   // A generic list object that holds the strings.
   List<String^>^ container = gcnew List<String^>;

public:
   // Define a delegate to handle string display.
   delegate void CheckAndDisplayDelegate(String^ str);

   // A method that adds more strings to the collection.
   void AddString(String^ str)
   {
      container->Add(str);
   }

   // Iterate through the strings and invoke the method(s) that the delegate points to.
   void DisplayAllQualified(CheckAndDisplayDelegate^ displayDelegate)
   {
      for each (String^ str in container)
         displayDelegate(str);
//       System::Collections::IEnumerator^ myEnum = container->GetEnumerator();
//       while ( myEnum->MoveNext() )
//       {
//          String^ str = safe_cast<String^>(myEnum->Current);
//          displayDelegate(str);
//      }
   }
};

//end of class StringContainer
// This class contains a few sample methods
ref class StringFuncs
{
public:

   // This method prints a String* that it is passed if the String* starts with a vowel
   static void ConStart(String^ str)
   {
      if (  !(str[ 0 ] == 'a' || str[ 0 ] == 'e' || str[ 0 ] == 'i' || str[ 0 ] == 'o' || str[ 0 ] == 'u') )
            Console::WriteLine( str );
   }

   // This method prints a String* that it is passed if the String* starts with a consonant
   static void VowelStart( String^ str )
   {
      if ( (str[ 0 ] == 'a' || str[ 0 ] == 'e' || str[ 0 ] == 'i' || str[ 0 ] == 'o' || str[ 0 ] == 'u') )
            Console::WriteLine( str );
   }
};

// This function demonstrates using Delegates, including using the Remove and
// Combine methods to create and modify delegate combinations.
int main()
{
   // Declare the StringContainer class and add some strings
   StringContainer^ container = gcnew StringContainer;
   container->AddString( "This" );
   container->AddString( "is" );
   container->AddString( "a" );
   container->AddString( "multicast" );
   container->AddString( "delegate" );
   container->AddString( "example" );

// RETURN HERE.
   // Create two delegates individually using different methods
   StringContainer::CheckAndDisplayDelegate^ conStart = gcnew StringContainer::CheckAndDisplayDelegate( StringFuncs::ConStart );
   StringContainer::CheckAndDisplayDelegate^ vowelStart = gcnew StringContainer::CheckAndDisplayDelegate( StringFuncs::VowelStart );

   // Get the list of all delegates assigned to this MulticastDelegate instance. 
   array<Delegate^>^ delegateList = conStart->GetInvocationList();
   Console::WriteLine("conStart contains {0} delegate(s).", delegateList->Length);
   delegateList = vowelStart->GetInvocationList();
   Console::WriteLine("vowelStart contains {0} delegate(s).\n", delegateList->Length );

   // Determine whether the delegates are System::Multicast delegates
   if ( dynamic_cast<System::MulticastDelegate^>(conStart) && dynamic_cast<System::MulticastDelegate^>(vowelStart) )
   {
      Console::WriteLine("conStart and vowelStart are derived from MulticastDelegate.\n");
   }

   // Execute the two delegates.
   Console::WriteLine("Executing the conStart delegate:" );
   container->DisplayAllQualified(conStart);
   Console::WriteLine();
   Console::WriteLine("Executing the vowelStart delegate:" );
   container->DisplayAllQualified(vowelStart);

   // Create a new MulticastDelegate and call Combine to add two delegates.
   StringContainer::CheckAndDisplayDelegate^ multipleDelegates =
           dynamic_cast<StringContainer::CheckAndDisplayDelegate^>(Delegate::Combine(conStart, vowelStart));

   // How many delegates does multipleDelegates contain?
   delegateList = multipleDelegates->GetInvocationList();
   Console::WriteLine("\nmultipleDelegates contains {0} delegates.\n", 
                      delegateList->Length );

   //       // Pass this multicast delegate to DisplayAllQualified.
   Console::WriteLine("Executing the multipleDelegate delegate.");
   container->DisplayAllQualified(multipleDelegates);
   // Call remove and combine to change the contained delegates.
   multipleDelegates = dynamic_cast<StringContainer::CheckAndDisplayDelegate^>
                      (Delegate::Remove(multipleDelegates, vowelStart));
   multipleDelegates = dynamic_cast<StringContainer::CheckAndDisplayDelegate^>
                      (Delegate::Combine(multipleDelegates, conStart));

   // Pass multipleDelegates to DisplayAllQualified again.
   Console::WriteLine("\nExecuting the multipleDelegate delegate with two conStart delegates:");
   container->DisplayAllQualified(multipleDelegates);
} 
// The example displays the following output:
//    conStart contains 1 delegate(s).
//    vowelStart contains 1 delegate(s).
//    
//    conStart and vowelStart are derived from MulticastDelegate.
//    
//    Executing the conStart delegate:
//    This
//    multicast
//    delegate
//    
//    Executing the vowelStart delegate:
//    is
//    a
//    example
//    
//    
//    multipleDelegates contains 2 delegates.
//    
//    Executing the multipleDelegate delegate.
//    This
//    is
//    a
//    multicast
//    delegate
//    example
//    
//    Executing the multipleDelegate delegate with two conStart delegates:
//    This
//    This
//    multicast
//    multicast
//    delegate
//    delegate
using System;
using System.Collections.Generic;

class StringContainer
{
   // Define a delegate to handle string display. 
   public delegate void CheckAndDisplayDelegate(string str);

   // A generic list object that holds the strings. 
   private List<String> container = new List<String>();

   // A method that adds strings to the collection. 
   public void AddString(string str) 
   {
      container.Add(str);
   }

   // Iterate through the strings and invoke the method(s) that the delegate points to. 
   public void DisplayAllQualified(CheckAndDisplayDelegate displayDelegate) 
   {
      foreach (var str in container) {
         displayDelegate(str);
      }
   }
 }    

// This class defines some methods to display strings. 
class StringExtensions
{
   // Display a string if it starts with a consonant. 
   public static void ConStart(string str) 
   {
      if (!(str[0]=='a'||str[0]=='e'||str[0]=='i'||str[0]=='o'||str[0]=='u'))
          Console.WriteLine(str);
   }

   // Display a string if it starts with a vowel.
   public static void VowelStart(string str) 
   {
      if ((str[0]=='a'||str[0]=='e'||str[0]=='i'||str[0]=='o'||str[0]=='u'))
          Console.WriteLine(str);
   }
}

// Demonstrate the use of delegates, including the Remove and 
// Combine methods to create and modify delegate combinations. 
class Test
{
   static public void Main()
   {
      // Declare the StringContainer class and add some strings
      StringContainer container = new StringContainer();
      container.AddString("This");
      container.AddString("is");
      container.AddString("a");
      container.AddString("multicast");
      container.AddString("delegate");
      container.AddString("example");

      // Create two delegates individually using different methods.
      StringContainer.CheckAndDisplayDelegate conStart = StringExtensions.ConStart;
      StringContainer.CheckAndDisplayDelegate vowelStart = StringExtensions.VowelStart;

      // Get the list of all delegates assigned to this MulticastDelegate instance. 
      Delegate[] delegateList = conStart.GetInvocationList();
      Console.WriteLine("conStart contains {0} delegate(s).", delegateList.Length);
      delegateList = vowelStart.GetInvocationList();
      Console.WriteLine("vowelStart contains {0} delegate(s).\n", delegateList.Length);

      // Determine whether the delegates are System.Multicast delegates. 
      if (conStart is System.MulticastDelegate && vowelStart is System.MulticastDelegate) 
          Console.WriteLine("conStart and vowelStart are derived from MulticastDelegate.\n");

      // Execute the two delegates.
      Console.WriteLine("Executing the conStart delegate:");
      container.DisplayAllQualified(conStart);
      Console.WriteLine();
      Console.WriteLine("Executing the vowelStart delegate:");
      container.DisplayAllQualified(vowelStart);
      Console.WriteLine();
      
      // Create a new MulticastDelegate and call Combine to add two delegates.
      StringContainer.CheckAndDisplayDelegate multipleDelegates = 
            (StringContainer.CheckAndDisplayDelegate) Delegate.Combine(conStart, vowelStart);

      // How many delegates does multipleDelegates contain?
      delegateList = multipleDelegates.GetInvocationList();
      Console.WriteLine("\nmultipleDelegates contains {0} delegates.\n",
                        delegateList.Length);

      // Pass this multicast delegate to DisplayAllQualified.
      Console.WriteLine("Executing the multipleDelegate delegate.");
      container.DisplayAllQualified(multipleDelegates);

      // Call remove and combine to change the contained delegates.
      multipleDelegates = (StringContainer.CheckAndDisplayDelegate) Delegate.Remove(multipleDelegates, vowelStart);
      multipleDelegates = (StringContainer.CheckAndDisplayDelegate) Delegate.Combine(multipleDelegates, conStart);

      // Pass multipleDelegates to DisplayAllQualified again.
      Console.WriteLine("\nExecuting the multipleDelegate delegate with two conStart delegates:");
      container.DisplayAllQualified(multipleDelegates);
   }
}
// The example displays the following output:
//    conStart contains 1 delegate(s).
//    vowelStart contains 1 delegate(s).
//    
//    conStart and vowelStart are derived from MulticastDelegate.
//    
//    Executing the conStart delegate:
//    This
//    multicast
//    delegate
//    
//    Executing the vowelStart delegate:
//    is
//    a
//    example
//    
//    
//    multipleDelegates contains 2 delegates.
//    
//    Executing the multipleDelegate delegate.
//    This
//    is
//    a
//    multicast
//    delegate
//    example
//    
//    Executing the multipleDelegate delegate with two conStart delegates:
//    This
//    This
//    multicast
//    multicast
//    delegate
//    delegate
Imports System.Collections.Generic

Class StringContainer
    ' Define a delegate to handle string display. 
    Delegate Sub CheckAndPrintDelegate(ByVal str As String)

    ' A generic list object that holds the strings.
    Private container As New List(Of String)()

     ' A method that adds strings to the collection. 
     Public Sub AddString(ByVal s As String)
        container.Add(s)
    End Sub

    ' Iterate through the strings and invoke the method(s) that the delegate points to.
    Public Sub DisplayAllQualified(ByVal displayDelegate As CheckAndPrintDelegate)
        For Each s In container
            displayDelegate(s)
        Next
    End Sub
End Class

' This class defines some methods to display strings. 
Class StringExtensions
    ' Display a string if it starts with a consonant. 
    Public Shared Sub ConStart(ByVal str As String)
        If Not (str.Chars(0) = "a"c Or str.Chars(0) = "e"c Or str.Chars(0) = "i"c _ 
                Or str.Chars(0) = "o"c Or str.Chars(0) = "u"c) Then
            Console.WriteLine(str)
        End If
    End Sub 

    ' Display a string if it starts with a vowel.
    Public Shared Sub VowelStart(ByVal str As String)
        If (str.Chars(0) = "a"c Or str.Chars(0) = "e"c Or str.Chars(0) = "i"c _
            Or str.Chars(0) = "o"c Or str.Chars(0) = "u"c) Then
            Console.WriteLine(str)
        End If
    End Sub 
End Class 

' Demonstrate the use of delegates, including the Remove and 
' Combine methods to create and modify delegate combinations. 
Class Test
    Public Shared Sub Main()
        ' Declare the StringContainer class and add some strings
        Dim container As New StringContainer()
        container.AddString("this")
        container.AddString("is")
        container.AddString("a")
        container.AddString("multicast")
        container.AddString("delegate")
        container.AddString("example")

        ' Create two delegates individually using different methods.
        Dim constart As StringContainer.CheckAndPrintDelegate = AddressOf StringExtensions.ConStart
        Dim vowelStart As StringContainer.CheckAndPrintDelegate = AddressOf StringExtensions.VowelStart

        ' Get the list of all delegates assigned to this MulticastDelegate instance. 
        Dim delegateList() As [Delegate] = conStart.GetInvocationList()
        Console.WriteLine("conStart contains {0} delegate(s).", delegateList.Length)
        delegateList = vowelStart.GetInvocationList()
        Console.WriteLine("vowelStart contains {0} delegate(s).", delegateList.Length)
        Console.WriteLine()
        
        ' Determine whether the delegates are System.Multicast delegates
        If TypeOf conStart Is System.MulticastDelegate And TypeOf vowelStart Is System.MulticastDelegate Then
            Console.WriteLine("conStart and vowelStart are derived from MulticastDelegate.")
            Console.WriteLine()
        End If

        ' Run the two single delegates one after the other.
        Console.WriteLine("Executing the conStart delegate:")
        container.DisplayAllQualified(conStart)
        Console.WriteLine("Executing the vowelStart delegate:")
        container.DisplayAllQualified(vowelStart)
        Console.WriteLine()

        ' Create a new MulticastDelegate and call Combine to add two delegates.
        Dim multipleDelegates As StringContainer.CheckAndPrintDelegate = 
                  CType([Delegate].Combine(conStart, vowelStart), 
                  StringContainer.CheckAndPrintDelegate)

        ' How many delegates does multipleDelegates contain?
        delegateList = multipleDelegates.GetInvocationList()
        Console.WriteLine("{1}multipleDelegates contains {0} delegates.{1}",
                          delegateList.Length, vbCrLf)

        ' Pass this mulitcast delegate to DisplayAllQualified.
        Console.WriteLine("Executing the multipleDelegate delegate.")
        container.DisplayAllQualified(multipleDelegates)

        ' Call remove and combine to change the contained delegates.
        multipleDelegates = CType([Delegate].Remove(multipleDelegates, vowelStart), 
                            StringContainer.CheckAndPrintDelegate)
        multipleDelegates = CType([Delegate].Combine(multipleDelegates, conStart), 
                            StringContainer.CheckAndPrintDelegate)

        ' Pass multipleDelegates to DisplayAllQualified again.
        Console.WriteLine()
        Console.WriteLine("Executing the multipleDelegate delegate with two conStart delegates:")
        container.DisplayAllQualified(multipleDelegates)
    End Sub 
End Class 
' The example displays the following output:
'    conStart contains 1 delegate(s).
'    vowelStart contains 1 delegate(s).
'    
'    conStart and vowelStart are derived from MulticastDelegate.
'    
'    Executing the conStart delegate:
'    This
'    multicast
'    delegate
'    
'    Executing the vowelStart delegate:
'    is
'    a
'    example
'    
'    
'    multipleDelegates contains 2 delegates.
'    
'    Executing the multipleDelegate delegate.
'    This
'    is
'    a
'    multicast
'    delegate
'    example
'    
'    Executing the multipleDelegate delegate with two conStart delegates:
'    This
'    This
'    multicast
'    multicast
'    delegate
'    delegate

注解

MulticastDelegate 是一个特殊类。MulticastDelegate is a special class. 编译器和其他工具可以派生自此类,但不能从它派生显式。Compilers and other tools can derive from this class, but you cannot derive from it explicitly. 也是如此的Delegate类。The same is true of the Delegate class.

除了委托类型的方法继承自MulticastDelegate,公共语言运行时提供两种特殊的方法:BeginInvokeEndInvokeIn addition to the methods that delegate types inherit from MulticastDelegate, the common language runtime provides two special methods: BeginInvoke and EndInvoke. 有关这些方法的详细信息,请参阅Calling Synchronous Methods AsynchronouslyFor more information about these methods, see Calling Synchronous Methods Asynchronously.

一个MulticastDelegate具有委托,调用调用列表,其中包含的一个或多个元素的链接的列表。A MulticastDelegate has a linked list of delegates, called an invocation list, consisting of one or more elements. 调用多路广播的委托时,委托调用列表中的显示顺序以同步方式调用。When a multicast delegate is invoked, the delegates in the invocation list are called synchronously in the order in which they appear. 如果该列表的执行过程中发生错误是引发异常。If an error occurs during execution of the list then an exception is thrown.

构造函数

MulticastDelegate(Object, String) MulticastDelegate(Object, String) MulticastDelegate(Object, String) MulticastDelegate(Object, String)

初始化 MulticastDelegate 类的新实例。Initializes a new instance of the MulticastDelegate class.

MulticastDelegate(Type, String) MulticastDelegate(Type, String) MulticastDelegate(Type, String) MulticastDelegate(Type, String)

初始化 MulticastDelegate 类的新实例。Initializes a new instance of the MulticastDelegate class.

方法

Clone() Clone() Clone() Clone()

创建委托的浅表副本。Creates a shallow copy of the delegate.

(Inherited from Delegate)
CombineImpl(Delegate) CombineImpl(Delegate) CombineImpl(Delegate) CombineImpl(Delegate)

将此 Delegate 与指定的 Delegate 合并,以形成一个新委托。Combines this Delegate with the specified Delegate to form a new delegate.

DynamicInvoke(Object[]) DynamicInvoke(Object[]) DynamicInvoke(Object[]) DynamicInvoke(Object[])

动态调用(后期绑定)由当前委托所表示的方法。Dynamically invokes (late-bound) the method represented by the current delegate.

(Inherited from Delegate)
DynamicInvokeImpl(Object[]) DynamicInvokeImpl(Object[]) DynamicInvokeImpl(Object[]) DynamicInvokeImpl(Object[])

处理整个调用列表。Processes the full invocation list.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

确定此多路广播委托和指定的对象是否相等。Determines whether this multicast delegate and the specified object are equal.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

返回此实例的哈希代码。Returns the hash code for this instance.

GetInvocationList() GetInvocationList() GetInvocationList() GetInvocationList()

按照调用顺序返回此多路广播委托的调用列表。Returns the invocation list of this multicast delegate, in invocation order.

GetMethodImpl() GetMethodImpl() GetMethodImpl() GetMethodImpl()

返回由当前的 MulticastDelegate 表示的静态方法。Returns a static method represented by the current MulticastDelegate.

GetObjectData(SerializationInfo, StreamingContext) GetObjectData(SerializationInfo, StreamingContext) GetObjectData(SerializationInfo, StreamingContext) GetObjectData(SerializationInfo, StreamingContext)

用序列化该实例所需的所有数据填充 SerializationInfo 对象。Populates a SerializationInfo object with all the data needed to serialize this instance.

GetType() GetType() GetType() GetType()

获取当前实例的 TypeGets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(Inherited from Object)
RemoveImpl(Delegate) RemoveImpl(Delegate) RemoveImpl(Delegate) RemoveImpl(Delegate)

从此 MulticastDelegate 的调用列表中移除与指定委托相等的元素。Removes an element from the invocation list of this MulticastDelegate that is equal to the specified delegate.

ToString() ToString() ToString() ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(Inherited from Object)

操作员

Equality(MulticastDelegate, MulticastDelegate) Equality(MulticastDelegate, MulticastDelegate) Equality(MulticastDelegate, MulticastDelegate) Equality(MulticastDelegate, MulticastDelegate)

确定两个 MulticastDelegate 对象是否相等。Determines whether two MulticastDelegate objects are equal.

Inequality(MulticastDelegate, MulticastDelegate) Inequality(MulticastDelegate, MulticastDelegate) Inequality(MulticastDelegate, MulticastDelegate) Inequality(MulticastDelegate, MulticastDelegate)

确定两个 MulticastDelegate 对象是否相等。Determines whether two MulticastDelegate objects are not equal.

属性

Method Method Method Method

获取委托所表示的方法。Gets the method represented by the delegate.

(Inherited from Delegate)
Target Target Target Target

获取类实例,当前委托将对其调用实例方法。Gets the class instance on which the current delegate invokes the instance method.

(Inherited from Delegate)

扩展方法

GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate)

获取指示指定委托表示的方法的对象。Gets an object that represents the method represented by the specified delegate.

适用于