Chain Of Responsibility

Chain Of Responsibility Pattern:很多对象由每一个对象对其下家的引用而连接起来形成一条链。请求在这个链上传递，直到链上的某一个对象决定处理此请求。发出这个请求的客户端并不知道链上的哪一个对象最终处理这个请求，这使系统可以在不影响客户端的情况下动态的重新组织链和分配责任。

1).

Handler.java

 

package com.flyinh.ihandler;

public interface Handler {
	void handleRequest(String str);
}

 

 HandlerA.java

 

package com.flyingh.handler;

import com.flyinh.ihandler.Handler;

public class HandlerA implements Handler {
	private Handler successor;

	public HandlerA(Handler successor) {
		super();
		this.successor = successor;
	}

	@Override
	public void handleRequest(String str) {
		// TODO Auto-generated method stub
		if(str.equals("A")){
			System.out.println("HandlerA.handleRequest()");
		}else{
			successor.handleRequest(str);
		}
	}

}

 

 HandlerB.java

 

package com.flyingh.handler;

import com.flyinh.ihandler.Handler;

public class HandlerB implements Handler {
	private Handler successor;

	public HandlerB(Handler successor) {
		super();
		this.successor = successor;
	}

	@Override
	public void handleRequest(String str) {
		// TODO Auto-generated method stub
		if (str.equals("B")) {
			System.out.println("HandlerB.handleRequest()");
		} else {
			successor.handleRequest(str);
		}
	}

}

 

 HandlerC.java

 

package com.flyingh.handler;

import com.flyinh.ihandler.Handler;

public class HandlerC implements Handler {
	private Handler successor;

	public HandlerC(Handler successor) {
		super();
		this.successor = successor;
	}

	@Override
	public void handleRequest(String str) {
		// TODO Auto-generated method stub
		if (str.equals("C")) {
			System.out.println("HandlerC.handleRequest()");
		} else {
			successor.handleRequest(str);
		}
	}

}

 

 OtherHandler.java

 

package com.flyingh.handler;

import com.flyinh.ihandler.Handler;

public class OtherHandler implements Handler {

	@Override
	public void handleRequest(String str) {
		// TODO Auto-generated method stub
		System.out.println("OtherHandler.handleRequest()");
	}

}

 

 Client.java

 

package com.flyingh.client;

import com.flyingh.handler.HandlerA;
import com.flyingh.handler.HandlerB;
import com.flyingh.handler.HandlerC;
import com.flyingh.handler.OtherHandler;
import com.flyinh.ihandler.Handler;

public class Client {
	public static void main(String[] args) {
		Handler handler = new HandlerA(new HandlerC(new HandlerB(
				new OtherHandler())));
		handler.handleRequest("B");
		System.out.println("************");
		handler.handleRequest("C");
		System.out.println("************");
		handler.handleRequest("A");
		System.out.println("************");
		handler.handleRequest("D");
	}
}

 

 程序运行结果如下：

 

HandlerB.handleRequest()
************
HandlerC.handleRequest()
************
HandlerA.handleRequest()
************
OtherHandler.handleRequest()

 2).

Handler.java

 

package com.flyingh.ihandler;

import com.flyingh.irequest.Request;

public interface Handler {
	void handleRequest(Request request);
}

 Request.java

 

package com.flyingh.irequest;

public interface Request {

}

 RequestA.java

 

package com.flyingh.request;

import com.flyingh.irequest.Request;

public class RequestA implements Request {

}

 RequestB.java

 

package com.flyingh.request;

import com.flyingh.irequest.Request;

public class RequestB implements Request {

}

 RequestC.java

 

package com.flyingh.request;

import com.flyingh.irequest.Request;

public class RequestC implements Request {

}

 OtherRequest.java

 

package com.flyingh.request;

import com.flyingh.irequest.Request;

public class OtherRequest implements Request {

}

 HandlerA.java

 

package com.flyingh.handler;

import com.flyingh.ihandler.Handler;
import com.flyingh.irequest.Request;
import com.flyingh.request.RequestA;

public class HandlerA implements Handler {
	private Handler successor;

	public HandlerA(Handler successor) {
		super();
		this.successor = successor;
	}

	@Override
	public void handleRequest(Request request) {
		// TODO Auto-generated method stub
		if (request instanceof RequestA) {
			System.out.println("HandlerA.handleRequest()");
		} else {
			successor.handleRequest(request);
		}
	}

}

 HandlerB.java

 

package com.flyingh.handler;

import com.flyingh.ihandler.Handler;
import com.flyingh.irequest.Request;
import com.flyingh.request.RequestB;

public class HandlerB implements Handler {
	private Handler successor;

	public HandlerB(Handler successor) {
		super();
		this.successor = successor;
	}

	@Override
	public void handleRequest(Request request) {
		// TODO Auto-generated method stub
		if (request instanceof RequestB) {
			System.out.println("HandlerB.handleRequest()");
		} else {
			successor.handleRequest(request);
		}
	}

}

 HandlerC.java

 

package com.flyingh.handler;

import com.flyingh.ihandler.Handler;
import com.flyingh.irequest.Request;
import com.flyingh.request.RequestC;

public class HandlerC implements Handler {
	private Handler successor;

	public HandlerC(Handler successor) {
		super();
		this.successor = successor;
	}

	@Override
	public void handleRequest(Request request) {
		// TODO Auto-generated method stub
		if (request instanceof RequestC) {
			System.out.println("HandlerC.handleRequest()");
		} else {
			successor.handleRequest(request);
		}
	}

}

 OtherHandler.java

 

package com.flyingh.handler;

import com.flyingh.ihandler.Handler;
import com.flyingh.irequest.Request;

public class OtherHandler implements Handler {

	@Override
	public void handleRequest(Request request) {
		// TODO Auto-generated method stub
		System.out.println("OtherHandler.handleRequest()");
	}

}

Client.java

package com.flyingh.client;

import com.flyingh.handler.HandlerA;
import com.flyingh.handler.HandlerB;
import com.flyingh.handler.HandlerC;
import com.flyingh.handler.OtherHandler;
import com.flyingh.ihandler.Handler;
import com.flyingh.irequest.Request;
import com.flyingh.request.OtherRequest;
import com.flyingh.request.RequestA;
import com.flyingh.request.RequestB;
import com.flyingh.request.RequestC;

public class Client {
	public static void main(String[] args) {
		Handler handler = new HandlerA(new HandlerC(new HandlerB(
				new OtherHandler())));
		Request requestB = new RequestB();
		handler.handleRequest(requestB);
		System.out.println("***************");
		Request requestA = new RequestA();
		handler.handleRequest(requestA);
		System.out.println("***************");
		Request requestC = new RequestC();
		handler.handleRequest(requestC);
		System.out.println("***************");
		Request otherRequest = new OtherRequest();
		handler.handleRequest(otherRequest);

	}
} 

程序运行结果如下：

HandlerB.handleRequest()
***************
HandlerA.handleRequest()
***************
HandlerC.handleRequest()
***************
OtherHandler.handleRequest()