设计模式学习之职责链模式

1、定义：

职责连模式（Chain of Responsibility），使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系，将这个对象连成一条链，并沿着链传递该请求，直到由一个对象处理它为止。

2、UML

ConcreteHandler1、ConcreteHandler2 :具体处理者类，处理它所负责的请求，可访问它的后继者，如果可处理该请求，就处理之，否则就将该请求转发给他的后继者。

3、职责链的好处

关键在与当客户提交一个请求时，请求是沿着链传递直至由一个ConcreateHander对象负责处理它
请求者不用管哪个对象来处理，反正该请求会被处理就是了
接受者和发送者都没有对方的明确信息，且链中的对象自己也不知道链的结构。结果是职责链可简化对象的互相连接，它们仅需保持一个指向其后继者的引用，而不需要保持它所有的候选接受者的引用，大大降低了耦合度
我们可以随时的增加或修改一个请求的结构，增强了给对象指派职责的灵活性

4、实例：

请求类

package com.zcr.chain;//申请public class Request{  //申请类别  private String requestType;    //申请内容  private String requestContent;    //数量  private int number;  public String getRequestType()  {    return requestType;  }  public void setRequestType(String requestType)  {    this.requestType = requestType;  }  public String getRequestContent()  {    return requestContent;  }  public void setRequestContent(String requestContent)  {    this.requestContent = requestContent;  }  public int getNumber()  {    return number;  }  public void setNumber(int number)  {    this.number = number;  }    }


package com.zcr.chain;//管理者public abstract class Manager{  protected String name;    public Manager()  {      }    //管理者的上级  protected Manager superior;    public Manager(String name)  {    this.name = name;  }    //设置管理者的上级  public void SetSuperior(Manager superior)  {    this.superior = superior;  }    //申请请求  abstract public void RequestApplications(Request request);}

package com.zcr.chain;//经理public class Majordomo extends Manager{  public Majordomo(String name)  {    this.name = name;  }    @Override  public void RequestApplications(Request request)  {    //经理所能有的权限就是可准许下属5天内的假期    if(request.getRequestType().equals("请假") && request.getNumber() <= 5)    {      System.out.println(name+":"+request.getRequestContent()+"数量"+request.getNumber()+"被批准");    }    else    {      //其余的申请都需转到上级      if(null != superior)      {        superior.RequestApplications(request);      }    }  }}

package com.zcr.chain;//总经理public class GeneralManager extends Manager{  public GeneralManager(String name)  {    this.name = name;  }      @Override  public void RequestApplications(Request request)  {    //总经理允许任意时间假期    if(request.getRequestType().equals("请假"))    {      System.out.println(name+":"+request.getRequestContent()+"数量"+request.getNumber()+"被批准");    }    else if(request.getRequestType().equals("加薪") && request.getNumber() <=500)    {      System.out.println(name+":"+request.getRequestContent()+"数量"+request.getNumber()+"被批准");    }    else if(request.getRequestType().equals("加薪") && request.getNumber() >500)    {      System.out.println(name+":"+request.getRequestContent()+"数量"+request.getNumber()+"再说把");    }  }  }

package com.zcr.chain;//经理public class CommonManager extends Manager{    public CommonManager(String name)  {    this.name = name;  }  @Override  public void RequestApplications(Request request)  {    //经理所能有的权限就是可准许下属两天内的假期    if(request.getRequestType().equals("请假") && request.getNumber() <= 2)    {      System.out.println(name+":"+request.getRequestContent()+"数量"+request.getNumber()+"被批准");    }    else    {      //其余的申请都需转到上级      if(null != superior)      {        superior.RequestApplications(request);      }    }  }}

package com.zcr.chain;public class ChainTest{  public static void main(String[] args)  {    CommonManager jinli = new CommonManager("经理");    Majordomo zongjian = new Majordomo("总监");    GeneralManager zongjingli = new GeneralManager("总经理");        //设置上机，完全根据实际需求来更改设置    jinli.SetSuperior(zongjian);    zongjian.SetSuperior(zongjingli);        Request request = new Request();    request.setRequestType("请假");    request.setRequestContent("XX来请假");    request.setNumber(1);    jinli.RequestApplications(request);        //客户端的申请都是有“经理”发起，但实际上谁来决策由具体管理类来处理，客户端不知道    Request request2 = new Request();    request2.setRequestType("请假");    request2.setRequestContent("XX来请假");    request2.setNumber(4);    jinli.RequestApplications(request2);        Request request3 = new Request();    request3.setRequestType("加薪");    request3.setRequestContent("XX请求加薪");    request3.setNumber(500);    jinli.RequestApplications(request3);            Request request4 = new Request();    request4.setRequestType("加薪");    request4.setRequestContent("XX请求加薪");    request4.setNumber(1000);    jinli.RequestApplications(request4);  }}

5、结果: