职责链模式的结构优化

package com;

public class Test {

	/**
	 * 职责链模式的结构优化
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//创建请求对象
		Request request = new Request();
		//创建具体处理者A
		ConcreateHandlerA ca = new ConcreateHandlerA();
		//创建具体处理者B
		ConcreateHandlerB cb = new ConcreateHandlerB();
		//创建最终处理者
		FinalHandler fh =  new FinalHandler();
		//添加职责链
		ca.addHandler(cb);
		cb.addHandler(fh);
		//通过职责链处理请求
		ca.sendToHandler(request);
	}
}

运行结果：
Processing first step
Processing second step
Processing final step

package com;

public class Request {
	//声明状态的变量
	public String status = "initial";
	
	//设置状态变量的方法
	public void setStatus(String status){
		this.status =status;
	}
	//获取状态变方法
	public String getStatus() {
		return status;
	}
	//处理相应的操作
	public void execute (String operation){
		System.out.println("Processing "+operation); 
	}
}

package com;

public interface Handler {
	//添加处理者方法
	public void addHandler(Handler handler);
	//发送请求对象到下一个处理者
	public void sendToHandler(Request request);
	//获取下一个处理者
	public Handler getHandler();
}

package com;

public class ConcreateHandlerA implements Handler {
	//声明下一个处理者
	Handler nextHandler = null;
	//构造器
	public ConcreateHandlerA(){
		
	}
	//添加处理者方法
	@Override
	public void addHandler(Handler handler) {
		nextHandler = handler;

	}
	//获取下一个处理者
	@Override
	public Handler getHandler() {
		return nextHandler;
	}

	//发送请求对象到下一个处理者
	@Override
	public void sendToHandler(Request request) {
		if(request.getStatus().equalsIgnoreCase("initial")){
			//对请求对象做相应的处理操作
			request.execute("first step");
			//为请求对象设置新的状态
			request.status = "first step finished";
			if(nextHandler != null){
				nextHandler.sendToHandler(request);
			}
		//如果不属于自己的职责就传递给下一个处理者
		}else if(nextHandler != null){
			nextHandler.sendToHandler(request);
		}
	}

}

package com;

public class ConcreateHandlerB implements Handler {
	Handler nextHandler = null;
	
	public ConcreateHandlerB (){
		
	}
	
	@Override
	public void addHandler(Handler handler) {
		nextHandler = handler;
	}

	@Override
	public Handler getHandler() {
		return nextHandler;
	}

	@Override
	public void sendToHandler(Request request) {
		if(request.getStatus().equalsIgnoreCase("first step finished")){
			request.execute("second step");
			request.status = "second step finished";
			if(nextHandler!=null){
				nextHandler.sendToHandler(request);
			}
		}else if(nextHandler!=null){
			nextHandler.sendToHandler(request);
		}
	}

}

package com;

public class FinalHandler implements Handler {
	Handler nextHandler = null;
	public FinalHandler(){
		
	}
	@Override
	public void addHandler(Handler handler) {
		nextHandler = handler;
	}

	@Override
	public Handler getHandler() {
		return nextHandler;
	}

	@Override
	public void sendToHandler(Request request) {
		if(request.getStatus().equalsIgnoreCase("second step finished")){
			request.execute("final step");
			request.status = "final step finished";
			if(nextHandler !=null){
				nextHandler.sendToHandler(request);
			}
		}else if(nextHandler !=null){
			nextHandler.sendToHandler(request);
		}
	}

}