MulticastDelegate多路广播委托
MulticastDelegate
备注
Delegate 方法
MulticastDelegate 方法
示例
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。
继承层次结构备注
MulticastDelegate 是一个特殊类。编译器和其他工具可以从此类派生,但是您不能显式地从此类进行派生。Delegate 类也是如此。
MulticastDelegate 拥有一个带有链接的委托列表,该列表称为调用列表,它包含一个或多个元素。在调用多路广播委托时,将按照调用列表中的委托出现的顺序来同步调用这些委托。如果在该列表的执行过程中发生错误,则会引发异常。
Combine | 已重载。 |
GetInvocationList |
Remove |
示例
using System;
// This class contains strings. It has a member method that
// accepts a multicast delegate as a parameter and calls it.
class HoldsStrings
{
// The following line causes the compiler to generate
// a new delegate class named CheckAndPrintDelegate that
// inherits from System.MulticastDelegate.
public delegate void CheckAndPrintDelegate(string str);
// An ArrayList that holds strings
private System.Collections.ArrayList myStringArray = new System.Collections.ArrayList();
// A method that adds more strings to the Collection
public void addstring( string str) {
myStringArray.Add(str);
}
// Iterate through the strings and invoke the method(s) that the delegate points to
public void PrintAllQualified(CheckAndPrintDelegate myDelegate) {
foreach (string str in myStringArray) {
myDelegate(str);
}
}
} //end of class HoldsStrings
// This class contains a few sample methods
class StringFuncs
{
// This method prints a string that it is passed if the string starts with a vowel
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);
}
// This method prints a string that it is passed if the string starts with a consonant
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);
}
}
// This class demonstrates using Delegates, including using the Remove and
// Combine methods to create and modify delegate combinations.
class Test
{
static public void Main()
{
// Declare the HoldsStrings class and add some strings
HoldsStrings myHoldsStrings = new HoldsStrings();
myHoldsStrings.addstring("This");
myHoldsStrings.addstring("is");
myHoldsStrings.addstring("a");
myHoldsStrings.addstring("multicast");
myHoldsStrings.addstring("delegate");
myHoldsStrings.addstring("example");
// Create two delegates individually using different methods
HoldsStrings.CheckAndPrintDelegate ConStartDel =
new HoldsStrings.CheckAndPrintDelegate(StringFuncs.ConStart);
HoldsStrings.CheckAndPrintDelegate VowStartDel =
new HoldsStrings.CheckAndPrintDelegate(StringFuncs.VowelStart);
// Demonstrate that MulticastDelegates may store only one delegate
Delegate [] DelegateList;
// Returns an array of all delegates stored in the linked list of the
// MulticastDelegate. In these cases the lists will hold only one (Multicast) delegate
DelegateList = ConStartDel.GetInvocationList();
Console.WriteLine("ConStartDel contains " + DelegateList.Length + " delegate(s).");
DelegateList = VowStartDel.GetInvocationList();
Console.WriteLine("ConStartVow contains " + DelegateList.Length + " delegate(s).");
// Determine whether the delegates are System.Multicast delegates
// if (ConStartDel is System.MulticastDelegate && VowStartDel is System.MulticastDelegate) {
Console.WriteLine("ConStartDel and ConStartVow are System.MulticastDelegates");
// }
// Run the two single delegates one after the other
Console.WriteLine("Running ConStartDel delegate:");
myHoldsStrings.PrintAllQualified(ConStartDel);
Console.WriteLine("Running VowStartDel delegate:");
myHoldsStrings.PrintAllQualified(VowStartDel);
// Create a new, empty MulticastDelegate
HoldsStrings.CheckAndPrintDelegate MultiDel;
// Delegate.Combine receives an unspecified number of MulticastDelegates as parameters
MultiDel = (HoldsStrings.CheckAndPrintDelegate) Delegate.Combine(ConStartDel, VowStartDel);
// How many delegates is this delegate holding?
DelegateList = MultiDel.GetInvocationList();
Console.WriteLine("\nMulitDel contains " + DelegateList.Length + " delegates.");
// What happens when this mulitcast delegate is passed to PrintAllQualified
Console.WriteLine("Running the multiple delegate that combined the first two");
myHoldsStrings.PrintAllQualified(MultiDel);
// The Remove and Combine methods modify the multiple delegate
MultiDel = (HoldsStrings.CheckAndPrintDelegate) Delegate.Remove(MultiDel, VowStartDel);
MultiDel = (HoldsStrings.CheckAndPrintDelegate) Delegate.Combine(MultiDel, ConStartDel);
// Finally, pass the combined delegates to PrintAllQualified again
Console.WriteLine("\nRunning the multiple delegate that contains two copies of ConStartDel:");
myHoldsStrings.PrintAllQualified(MultiDel);
return;
} //end of main
} //end of Test
// This class contains strings. It has a member method that
// accepts a multicast delegate as a parameter and calls it.
class HoldsStrings
{
// The following line causes the compiler to generate
// a new delegate class named CheckAndPrintDelegate that
// inherits from System.MulticastDelegate.
public delegate void CheckAndPrintDelegate(string str);
// An ArrayList that holds strings
private System.Collections.ArrayList myStringArray = new System.Collections.ArrayList();
// A method that adds more strings to the Collection
public void addstring( string str) {
myStringArray.Add(str);
}
// Iterate through the strings and invoke the method(s) that the delegate points to
public void PrintAllQualified(CheckAndPrintDelegate myDelegate) {
foreach (string str in myStringArray) {
myDelegate(str);
}
}
} //end of class HoldsStrings
// This class contains a few sample methods
class StringFuncs
{
// This method prints a string that it is passed if the string starts with a vowel
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);
}
// This method prints a string that it is passed if the string starts with a consonant
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);
}
}
// This class demonstrates using Delegates, including using the Remove and
// Combine methods to create and modify delegate combinations.
class Test
{
static public void Main()
{
// Declare the HoldsStrings class and add some strings
HoldsStrings myHoldsStrings = new HoldsStrings();
myHoldsStrings.addstring("This");
myHoldsStrings.addstring("is");
myHoldsStrings.addstring("a");
myHoldsStrings.addstring("multicast");
myHoldsStrings.addstring("delegate");
myHoldsStrings.addstring("example");
// Create two delegates individually using different methods
HoldsStrings.CheckAndPrintDelegate ConStartDel =
new HoldsStrings.CheckAndPrintDelegate(StringFuncs.ConStart);
HoldsStrings.CheckAndPrintDelegate VowStartDel =
new HoldsStrings.CheckAndPrintDelegate(StringFuncs.VowelStart);
// Demonstrate that MulticastDelegates may store only one delegate
Delegate [] DelegateList;
// Returns an array of all delegates stored in the linked list of the
// MulticastDelegate. In these cases the lists will hold only one (Multicast) delegate
DelegateList = ConStartDel.GetInvocationList();
Console.WriteLine("ConStartDel contains " + DelegateList.Length + " delegate(s).");
DelegateList = VowStartDel.GetInvocationList();
Console.WriteLine("ConStartVow contains " + DelegateList.Length + " delegate(s).");
// Determine whether the delegates are System.Multicast delegates
// if (ConStartDel is System.MulticastDelegate && VowStartDel is System.MulticastDelegate) {
Console.WriteLine("ConStartDel and ConStartVow are System.MulticastDelegates");
// }
// Run the two single delegates one after the other
Console.WriteLine("Running ConStartDel delegate:");
myHoldsStrings.PrintAllQualified(ConStartDel);
Console.WriteLine("Running VowStartDel delegate:");
myHoldsStrings.PrintAllQualified(VowStartDel);
// Create a new, empty MulticastDelegate
HoldsStrings.CheckAndPrintDelegate MultiDel;
// Delegate.Combine receives an unspecified number of MulticastDelegates as parameters
MultiDel = (HoldsStrings.CheckAndPrintDelegate) Delegate.Combine(ConStartDel, VowStartDel);
// How many delegates is this delegate holding?
DelegateList = MultiDel.GetInvocationList();
Console.WriteLine("\nMulitDel contains " + DelegateList.Length + " delegates.");
// What happens when this mulitcast delegate is passed to PrintAllQualified
Console.WriteLine("Running the multiple delegate that combined the first two");
myHoldsStrings.PrintAllQualified(MultiDel);
// The Remove and Combine methods modify the multiple delegate
MultiDel = (HoldsStrings.CheckAndPrintDelegate) Delegate.Remove(MultiDel, VowStartDel);
MultiDel = (HoldsStrings.CheckAndPrintDelegate) Delegate.Combine(MultiDel, ConStartDel);
// Finally, pass the combined delegates to PrintAllQualified again
Console.WriteLine("\nRunning the multiple delegate that contains two copies of ConStartDel:");
myHoldsStrings.PrintAllQualified(MultiDel);
return;
} //end of main
} //end of Test