职责链模式(Chain of Responsibility):使多个对象都有机会处理请求,从而避免请求的发送者和接受者之间的耦合关系。将这个对象连成一条链,并沿着这条链传递该请求,直到有一个对象处理它为止。
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namespace ChainDesign { public abstract class Handler { protected Handler successor; public void SetSuccessor(Handler successor) { this.successor = successor; } public abstract void HandleRequest(int request); } public class ConcreteHandler1 : Handler { public override void HandleRequest(int request) { if(request>=0&&request<10) { Console.WriteLine("{0}处理请求{1}", this.GetType().Name, request); } else if(successor!=null) { successor.HandleRequest(request); } } } public class ConcreteHandler2 : Handler { public override void HandleRequest(int request) { if (request >= 10 && request < 20) { Console.WriteLine("{0}处理请求{1}", this.GetType().Name, request); } else if (successor != null) { successor.HandleRequest(request); } } } public class ConcreteHandler3 : Handler { public override void HandleRequest(int request) { if (request >= 20 && request < 30) { Console.WriteLine("{0}处理请求{1}", this.GetType().Name, request); } else if (successor != null) { successor.HandleRequest(request); } } } }
测试代码:
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Handler h1 = new ConcreteHandler1(); Handler h2 = new ConcreteHandler2(); Handler h3 = new ConcreteHandler3(); h1.SetSuccessor(h2); h2.SetSuccessor(h3); int[] requests = { 2, 5, 14, 22, 18, 3, 27, 20 }; foreach(int request in requests) { h1.HandleRequest(request); }