Java设计模式-----Chain of Responsibility职责链模式-优快云博客

本文通过一个生动的例子介绍了职责链设计模式。该模式允许多个处理对象组成一条链，并在这条链上传递请求，直到其中一个对象处理该请求。文章通过实现一个Boy类和多个Handler接口的具体实现来展示这一过程。

源自：http://www.blogjava.net/flustar/archive/2007/12/14/cor.html

Chain of Responsibility职责链模式：

为了避免请求的发送者和接收者之间的耦合关系，使多个接受对象都有机会处理请求。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

例子：

public class Boy {
	
	private boolean hasCar; // 是否有车
	private boolean hasHouse; // 是否有房
	private boolean hasResponsibility; // 是否有责任心

	public Boy() {
	}

	public Boy(boolean hasCar, boolean hasHouse, boolean hasResponsibility) {
		this.hasCar = hasCar;
		this.hasHouse = hasHouse;
		this.hasResponsibility = hasResponsibility;
	}

	public boolean isHasCar() {
		return hasCar;
	}

	public void setHasCar(boolean hasCar) {
		this.hasCar = hasCar;
	}

	public boolean isHasHouse() {
		return hasHouse;
	}

	public void setHasHouse(boolean hasHouse) {
		this.hasHouse = hasHouse;
	}

	public boolean isHasResponsibility() {
		return hasResponsibility;
	}

	public void setHasResponsibility(boolean hasResponsibility) {
		this.hasResponsibility = hasResponsibility;
	}
}

public interface Handler {
	 public void handleRequest(Boy boy);
}

public class HouseHandler implements Handler {
	
	private Handler handler;

	public HouseHandler(Handler handler) {

		this.handler = handler;
	}

	public Handler getHandler() {
		return handler;
	}

	public void setHandler(Handler handler) {
		this.handler = handler;
	}

	public void handleRequest(Boy boy) {
		if (boy.isHasHouse()) {
			System.out.println("没想到吧，我还有房子");
		} else {
			System.out.println("我也没有房");
			handler.handleRequest(boy);
		}
	}
}

public class CarHandler implements Handler {

	private Handler handler;

	public CarHandler(Handler handler) {
		this.handler = handler;
	}

	public Handler getHandler() {
		return handler;
	}

	public void setHandler(Handler handler) {
		this.handler = handler;
	}

	public void handleRequest(Boy boy) {
		if (boy.isHasCar()) {
			System.out.println("呵呵，我有辆车");
		} else {
			System.out.println("我没有车");
			handler.handleRequest(boy);
		}
	}
}

public class ResponsibilityHandler implements Handler {

	private Handler handler;

	public ResponsibilityHandler(Handler handler) {
		this.handler = handler;
	}

	public Handler getHandler() {
		return handler;
	}

	public void setHandler(Handler handler) {
		this.handler = handler;
	}

	public void handleRequest(Boy boy) {
		if (boy.isHasResponsibility()) {
			System.out.println("我只有一颗带Responsibility的心");
		} else {
			System.out.println("更没有责任心");
			handler.handleRequest(boy);
		}
	}
}

public class Girl {
	
	public static void main(String[] args) {
		
		Boy boy = new Boy(false, false, true);// 这个boy没有车，也没有房，不过很有责任心
		Handler handler = new CarHandler(new HouseHandler(
				new ResponsibilityHandler(null)));// 也可以使用setHanlder方法
		handler.handleRequest(boy);
	}
}