C#委托-知识点总结
2010-11-21 23:57
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1.委托概念:
当要把方法传送给其它方法时,需要使用委托。委托是一种特殊的引用类型,用于封装命名方法(静态或实例)或匿名方法。委托的作用相当于给方法签名指定名称。使用delegate关键字来声明一个委托引用类型,这种特殊的引用类型称为委托。
2.定义委托:
告诉编译器某个委托引用了某种类型的方法。
定义引用无参数的方法的委托
delegate string TestDelegate1 ();//定义了一个委托TestDelegate1,引用了返回值类型为string的方法,此方法不带任何参数。
定义引用有参数的方法的委托
delegate void TestDelegate2 (string message);//定义了一个委托TestDelegate2,引用了返回值类型为void的方法,此方法带一个string参数。
3.实例化委托:
通过将委托与命名方法(静态或实例)或匿名方法关联,可以实例化委托。委托的实例仍称为委托。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//定义委托TestDelegate,代表带一个string参数的void返回类型方法
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate void TestDelegate(string name);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//定义类TestClass,包含静态命名方法和实例命名方法
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
public class TestClass
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
public static void StaticMethod(string name)//静态命名方法
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
Console.WriteLine(name +" Called StaticMethod");
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
public void NoStaticMethod(string name)//实例命名方法
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
Console.WriteLine(name +" Called NoStaticMethod");
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
与命名方法关联时委托在语法上总是带有一个参数的构造函数,这个参数就是委托引用的方法,这个方法必须匹配最初定义委托时的签名,即方法返回值类型和参数序列必须都相匹配。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//与静态命名方法关联实例化委托
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate1 = new TestDelegate(TestClass. StaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//与实例命名方法关联实例化委托
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestClass testClass = new TestClass();
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate2 = new TestDelegate(testClass. NoStaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
与匿名方法关联时,匿名方法必须匹配最初定义委托时的签名,即方法返回值类型和参数序列必须都相匹配。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//与匿名方法关联实例化委托
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate3 = delegate(string name)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
Console.WriteLine(name + " Called AnonyMethod");
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
};
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4.多播委托:
委托可以包含多个方法,这种委托称为多播委托。多播委托只能引用返回值为void的方法。运算符有+、+=、-、-=,用来增加方法和删除方法。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
// 在delegate委托中增加NoStaticMethod方法
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate = new TestDelegate(TestClass. StaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
Delegate += new TestDelegate(testClass. NoStaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5.使用委托:
使用委托即通过委托的实例调用委托引用的方法,委托的实例名后面的括号包含的参数与委托引用的方法参数匹配。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate1(“XieXiaohua”);// 使用与静态命名方法关联的委托实例
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate2(“XieXiaohua”);// 使用与实例命名方法关联的委托实例
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate3(“XieXiaohua”);// 使用与匿名方法关联的委托实例
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6.委托总结:
委托使用三步曲:定义->关联->调用
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//定义(定义委托)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate string MyDelegate();
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//关联(通过关联方法实例化委托)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
MyDelegate d = new MyDelegate(MyClass.MyMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//调用(通过委托的实例调用方法)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
string ret = d();
当要把方法传送给其它方法时,需要使用委托。委托是一种特殊的引用类型,用于封装命名方法(静态或实例)或匿名方法。委托的作用相当于给方法签名指定名称。使用delegate关键字来声明一个委托引用类型,这种特殊的引用类型称为委托。
2.定义委托:
告诉编译器某个委托引用了某种类型的方法。
定义引用无参数的方法的委托
delegate string TestDelegate1 ();//定义了一个委托TestDelegate1,引用了返回值类型为string的方法,此方法不带任何参数。
定义引用有参数的方法的委托
delegate void TestDelegate2 (string message);//定义了一个委托TestDelegate2,引用了返回值类型为void的方法,此方法带一个string参数。
3.实例化委托:
通过将委托与命名方法(静态或实例)或匿名方法关联,可以实例化委托。委托的实例仍称为委托。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//定义委托TestDelegate,代表带一个string参数的void返回类型方法
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate void TestDelegate(string name);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//定义类TestClass,包含静态命名方法和实例命名方法
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
public class TestClass
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
public static void StaticMethod(string name)//静态命名方法
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
Console.WriteLine(name +" Called StaticMethod");
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
public void NoStaticMethod(string name)//实例命名方法
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
Console.WriteLine(name +" Called NoStaticMethod");
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
与命名方法关联时委托在语法上总是带有一个参数的构造函数,这个参数就是委托引用的方法,这个方法必须匹配最初定义委托时的签名,即方法返回值类型和参数序列必须都相匹配。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//与静态命名方法关联实例化委托
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate1 = new TestDelegate(TestClass. StaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//与实例命名方法关联实例化委托
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestClass testClass = new TestClass();
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate2 = new TestDelegate(testClass. NoStaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
与匿名方法关联时,匿名方法必须匹配最初定义委托时的签名,即方法返回值类型和参数序列必须都相匹配。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//与匿名方法关联实例化委托
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate3 = delegate(string name)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](http://www.cnblogs.com/Images/dot.gif)
{
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
Console.WriteLine(name + " Called AnonyMethod");
![](http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
};
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4.多播委托:
委托可以包含多个方法,这种委托称为多播委托。多播委托只能引用返回值为void的方法。运算符有+、+=、-、-=,用来增加方法和删除方法。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
// 在delegate委托中增加NoStaticMethod方法
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
TestDelegate delegate = new TestDelegate(TestClass. StaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
Delegate += new TestDelegate(testClass. NoStaticMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5.使用委托:
使用委托即通过委托的实例调用委托引用的方法,委托的实例名后面的括号包含的参数与委托引用的方法参数匹配。
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate1(“XieXiaohua”);// 使用与静态命名方法关联的委托实例
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate2(“XieXiaohua”);// 使用与实例命名方法关联的委托实例
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate3(“XieXiaohua”);// 使用与匿名方法关联的委托实例
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6.委托总结:
委托使用三步曲:定义->关联->调用
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//定义(定义委托)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
delegate string MyDelegate();
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//关联(通过关联方法实例化委托)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
MyDelegate d = new MyDelegate(MyClass.MyMethod);
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
//调用(通过委托的实例调用方法)
![](http://www.cnblogs.com/Images/OutliningIndicators/None.gif)
string ret = d();
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