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;
@Override
public 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;

@Override
public 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)