责任链模式(Chain of Responsibility)

责任链模式是对象的行为模式。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直接的耦合关系。

public abstract class Handler {protected Handler successor;public abstract void handlerRequest(String condition);protected Handler getSuccessor() {return successor;}public void setSuccessor(Handler successor) {this.successor = successor;}
}public class ConcreteHandler1 extends Handler{@Overridepublic void handlerRequest(String condition) {// TODO Auto-generated method stub// 如果是自己的责任，就自己处理，负责传给下家处理if(condition.equals("ConcreteHandler1")){System.out.println( "ConcreteHandler1 handled ");return ;}else{System.out.println( "ConcreteHandler1 passed ");getSuccessor().handlerRequest(condition);}
}public class ConcreteHandler2 extends Handler{@Overridepublic void handlerRequest(String condition) {// TODO Auto-generated method stub// 如果是自己的责任，就自己处理，负责传给下家处理if(condition.equals("ConcreteHandler2")){System.out.println( "ConcreteHandler2 handled ");return ;}else{System.out.println( "ConcreteHandler2 passed ");getSuccessor().handlerRequest(condition);}}
}public class ConcreteHandlerN extends Handler{@Overridepublic void handlerRequest(String condition) {// TODO Auto-generated method stubSystem.out.println( "ConcreteHandlerN handled");}
}//测试
Handler handler1 = new ConcreteHandler1();
Handler handler2 = new ConcreteHandler2();
Handler handlern = new ConcreteHandlerN();
//链起来
handler1.setSuccessor(handler2);
handler2.setSuccessor(handlern);
//假设这个请求是ConcreteHandler2的责任
handler1.handlerRequest("ConcreteHandler2");public static void main(String[] args) {// TODO Auto-generated method stubHandler handler1 = new ConcreteHandler1();Handler handler2 = new ConcreteHandler2();Handler handlern = new ConcreteHandlerN();		//链起来handler1.setSuccessor(handler2);handler2.setSuccessor(handlern);		//假设这个请求是ConcreteHandler2的责任handler1.handlerRequest("ConcreteHandler2");
}