在利用委托进行函数代理的时候，我们习惯于用+=来把一个符合条件的委托加入委托链之中，如果加入了多个这样的函数，怎么一一对这些函数取返回值呢？请看下面的一个实例：
View Code using System;namespace GetInvocationListDaemonCAPP{ public delegate string TestDelegate(); public class Program { static void Main(string[] args) { DelegateClass delegateClass = new DelegateClass(); TestMethodOne one = new TestMethodOne(); TestMethodTwo two = new TestMethodTwo(); TestMethodThree three = new TestMethodThree(); TestMethodFour four = new TestMethodFour(); delegateClass.testDelegate += one.Say; delegateClass.testDelegate += two.Say; delegateClass.testDelegate += three.Say; delegateClass.testDelegate += four.Say; delegateClass.InvokeDelegate(); Console.ReadKey(); } } public class DelegateClass { public TestDelegate testDelegate; public void InvokeDelegate() { if (null != testDelegate) { string resultStr = testDelegate(); Console.WriteLine(resultStr); } } } public class TestMethodOne { public string Say() { return "You called me from TestMethodOne~~~"; } } public class TestMethodTwo { public string Say() { return "You called me from TestMethodTwo~~~"; } } public class TestMethodThree { public string Say() { return "You called me from TestMethodThree~~~"; } } public class TestMethodFour { public string Say() { return "You called me from TestMethodFour~~~"; } }} 在这个示例中，我用了一个委托代理了四个类型相同，返回值相同的函数，那么当我要获取这些函数的返回值的时候，会得到什么样的结果呢？
You called me from TestMethodFour~~~
结果就是上面的输出，原来，像这种方式的委托操作，会保留最后一个输出，前面几个都被OverWrite掉了。
为了解决这个问题，GetInvocationList方法出现了。 View Code using System;namespace GetInvocationListDaemonCAPP{ public delegate string TestDelegate(); public class Program { static void Main(string[] args) { DelegateClass delegateClass = new DelegateClass(); TestMethodOne one = new TestMethodOne(); TestMethodTwo two = new TestMethodTwo(); TestMethodThree three = new TestMethodThree(); TestMethodFour four = new TestMethodFour(); delegateClass.testDelegate += one.Say; delegateClass.testDelegate += two.Say; delegateClass.testDelegate += three.Say; delegateClass.testDelegate += four.Say; delegateClass.InvokeDelegate(); Console.ReadKey(); } } public class DelegateClass { public TestDelegate testDelegate; public void InvokeDelegate() { if (null != testDelegate) { //遍历委托链表 foreach (Delegate dele in testDelegate.GetInvocationList()) { //类型转换 TestDelegate delegateClass = (TestDelegate)dele; //调用并 得到返回结果 string resultStr = delegateClass(); Console.WriteLine(resultStr); } } } } public class TestMethodOne { public string Say() { return "You called me from TestMethodOne~~~"; } } public class TestMethodTwo { public string Say() { return "You called me from TestMethodTwo~~~"; } } public class TestMethodThree { public string Say() { return "You called me from TestMethodThree~~~"; } } public class TestMethodFour { public string Say() { return "You called me from TestMethodFour~~~"; } }} 这样操作后，得到的运行结果如下：
You called me from TestMethodOne~~~You called me from TestMethodTwo~~~You called me from TestMethodThree~~~You called me from TestMethodFour~~~