设计模式 - chain of Responsibility

Chain of Responsibility也就是职责链模式,通过使用链式结构,使对象都有机会处理请求,从而避免请求的发送者与接受者间的耦合关系。将这些对象连成链,并沿着该链传递请求,直到有对象处理为止。

实现的关键在于处理对象的转发机制,也就是如果我能处理,那么我处理,如果不能处理,就转发给后面的对象处理。但普通的实现方法中,该处理对象必须保有后面对象的引用,也就是仍存在一定程度的耦合。理想的情况是处理对象(handler)之间彼此不知对方,通过另外的机制完成对象传递。

Apache有开源框架实现职责链模式,用户可以通过配置xml来决定请求的处理顺序,而handler只需实现固定接口即可。

举个例子:

某皮包公司有各种总,但这些总共享三个秘书(不要理解错了),分为为lilyzhou, LucyWang和RuHua。总们签署的文件会交给秘书们处理,lilyzhou是大秘,LucyWang是二秘,RuHua是三秘。liliy不愿意处理的文件交给LucyWang,LucyWang不愿意处理的交给Ruhua。ruhua没有不愿意的权利,只能自己处理。

秘书们的特殊爱好如下:lilyzhou只处理boss.zhang签署的文件(她认为自己是秘书中的老大),LucyWang只处理boss.li签署的文件,Ruahua处理她们不愿意的处理的文件(有人的地方就有江湖啊)

下面贴出代码:

package com.inspur.jiyq.designpattern.responsibilitychain;


public interface Secretary {
	public void handover(ImporantFile file);
	
	public void dealWithIt(ImporantFile file);
}

  

package com.inspur.jiyq.designpattern.responsibilitychain;

public class ImporantFile {
	/**
	 * 文件签名 boss.zhang, boss.li, bossWang
	 */
	private String signature;

	public String getSignature() {
		return signature;
	}

	public void setSignature(String signature) {
		this.signature = signature;
	}
}

  

package com.inspur.jiyq.designpattern.responsibilitychain;

import com.inspur.jiyq.designpattern.responsibilitychain.impl.LilyZhou;

public class BossOnDuty {
	public static void main(String[] args)
	{
		ImporantFile file = new ImporantFile();
		file.setSignature("boss.sun");
		
		Secretary secretary = new LilyZhou();
		secretary.handover(file);
	}
}

  

package com.inspur.jiyq.designpattern.responsibilitychain.impl;

import com.inspur.jiyq.designpattern.responsibilitychain.ImporantFile;
import com.inspur.jiyq.designpattern.responsibilitychain.Secretary;

public class LilyZhou implements Secretary {
	private Secretary lucyWang = new LucyWang();

	@Override
	public void handover(ImporantFile file) {
		if (file.getSignature().equals("boss.zhang")) {
			dealWithIt(file);
		} else {
			lucyWang.handover(file);
		}
	}

	@Override
	public void dealWithIt(ImporantFile file) {
		// TODO Auto-generated method stub
		System.out.println("lilyzhou deal with it.");
	}

}

  

package com.inspur.jiyq.designpattern.responsibilitychain.impl;

import com.inspur.jiyq.designpattern.responsibilitychain.ImporantFile;
import com.inspur.jiyq.designpattern.responsibilitychain.Secretary;

public class LucyWang implements Secretary{
	private Secretary ruhua = new RuHua();

	@Override
	public void handover(ImporantFile file) {
		if (file.getSignature().equals("boss.li")) {
			dealWithIt(file);
		} else {
			ruhua.handover(file);
		}
	}

	@Override
	public void dealWithIt(ImporantFile file) {
		System.out.println("lucyWang deal with it.");
	}

}

  

package com.inspur.jiyq.designpattern.responsibilitychain.impl;

import com.inspur.jiyq.designpattern.responsibilitychain.ImporantFile;
import com.inspur.jiyq.designpattern.responsibilitychain.Secretary;

public class RuHua implements Secretary {

	@Override
	public void handover(ImporantFile file) {
		// RuHua can not deliever it to anybody else
		dealWithIt(file);
	}

	@Override
	public void dealWithIt(ImporantFile file) {
		System.out.println("RuHua deal with it.");
	}

}

  

posted @ 2014-04-16 16:38  纪玉奇  阅读(201)  评论(0编辑  收藏  举报