设计模式系列之二_责任链模式(Chain of Responsibility)

1.职责链模式定义

  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。

2.Chain of Responsibility模式主要涉及两个角色

  1)抽象处理者角色（Handler）：它定义了一个处理请求的接口。当然对于链子的不同实现，
也可以在这个角色中实现后继链。
  2)具体处理者角色（ConcreteHandler）：实现抽象角色中定义的接口，并处理它所负责的请求。

如果不能处理则访问它的后继者。

如下图：

3.职责链模式应用--请假管理

假设请假的流程如下：
  1.在公司里，如果你的请假时间小于0.5天，那么只需要向项目经理打声招呼就OK了。
  2.如果超过了0.5天，但是还小于2天，那么就要去找人事部处理，当然，这就要扣工资了。

  3.如果超过了2天，你就需要去找总经理了，工资当然也玩完了。

4.Java代码实现

如下：

/** * @Title:请假请求类 * @Description:TODO * @Company: Orclight's Studio * @author: shuzl  2013-3-12 上午09:40:13 * @motto: Never put off what you can do today until Tomorrow * @version 1.0.0  */public class Request {private float day;private String reason;public Request() {}public Request(int day,String reason) {this.day=day;this.reason=reason;}public float getDay() {return day;}public void setDay(float day) {this.day = day;}public String getReason() {return reason;}public void setReason(String reason) {this.reason = reason;}}

/** * @Title:请假处理接口 * @Description:TODO * @Company: Orclight's Studio * @author: shuzl  2013-3-12 上午09:43:25 * @motto: Never put off what you can do today until Tomorrow * @version 1.0.0  */public interface ProcessRequest{public boolean handle(Request request);}

/** * @Title:项目经理--实现请假接口 * @Description:TODO * @Company: Orclight's Studio * @author: shuzl  2013-3-12 上午09:44:38 * @motto: Never put off what you can do today until Tomorrow * @version 1.0.0  */public class ProjectManager implements ProcessRequest{private ProcessRequest boss;public boolean handle(Request request) {float day=request.getDay();if(day<=0.5) {System.out.println("PM 已经批准处理成功！请假原因："+request.getReason());return true;}return boss.handle(request);}public ProcessRequest getBoss() {return boss;}public void setBoss(ProcessRequest boss) {this.boss = boss;}}

/** * @Title:项目经理--实现请假接口 * @Description:TODO * @Company: Orclight's Studio * @author: shuzl  2013-3-12 上午09:47:39 * @motto: Never put off what you can do today until Tomorrow * @version 1.0.0  */public class HR implements ProcessRequest{private ProcessRequest boss;@Overridepublic boolean handle(Request request) {float day = request.getDay();if(day>0.5&&day<=2) {System.out.println("HR已经批准，处理成功！请假原因："+request.getReason());return true;} return boss.handle(request);}public ProcessRequest getBoss() {return boss;}public void setBoss(ProcessRequest boss) {this.boss = boss;}}

/** * @Title:经理--实现请假接口 * @Description:TODO * @Company: Orclight's Studio * @author: shuzl  2013-3-12 上午09:50:38 * @motto: Never put off what you can do today until Tomorrow * @version 1.0.0  */public class Manager implements ProcessRequest{private ProcessRequest boss;@Overridepublic boolean handle(Request request) {float day=request.getDay();if(day>2) {System.out.println("总经理审批通过！请假原因："+request.getReason());}return false;}public ProcessRequest getBoss() {return boss;}public void setBoss(ProcessRequest boss) {this.boss = boss;}}

/** * @Title:请假流程测试类 * @Description:TODO * @Company: Orclight's Studio * @author: shuzl  2013-3-12 上午09:53:24 * @motto: Never put off what you can do today until Tomorrow * @version 1.0.0  */public class TestRequest {public static void main(String[] args) {//1.发出请求Request request = new Request(3,"病假");//2.创建处理对象ProjectManager pm = new ProjectManager();HR hr = new HR();Manager manager = new Manager();//3.设置chain的流向，关联关系pm.setBoss(hr);hr.setBoss(manager);//4.处理请求pm.handle(request);}}

参考文章：

1.设计模式学习笔记(十九)—Chain of Responsibility职责链模式  

2.重温设计模式（三）——职责链模式(chain of responsibility)