设计模式（五）责任链模式

一.什么是责任链模式?

    责任链就是从一个起点发起请求，然后沿着任务链依次传递给每一个节点上的对象，直到有一个节点处理这个请求为止。

二.责任链模式实例实现?

public abstract class ConsumeHandler {  
    private ConsumeHandler nextHandler;  
  
    public ConsumeHandler getNextHandler(){  
        return nextHandler;  
    }  
  
    public void setNextHandler(ConsumeHandler nextHandler){  
        this.nextHandler=nextHandler;  
    }  
  
    /** 
     * user申请人  free报销费用 
     */  
    public abstract void doHandler(String user,double free);  
}  

//项目经理  
public class ProjectHandler extends ConsumeHandler {  
    @Override  
    public void doHandler(String user, double free) {  
        if (free < 500){  
            if (user.equals("lwx")){  
                System.out.print("给予报销："+free);  
            }else{  
                System.out.print("报销不通过");  
            }  
        }else{  
            if (getNextHandler()!=null){  
                getNextHandler().doHandler(user,free);  
            }  
        }  
    }  
}  

//部门经理  
public class DeptHandler extends ConsumeHandler {  
    @Override  
    public void doHandler(String user, double free) {  
        if (free<1000){  
            if (user.equals("zy")){  
                System.out.print("给予报销:"+free);  
            }else{  
                System.out.println("报销不通过");  
            }  
        }else{  
            if (getNextHandler()!=null){  
                getNextHandler().doHandler(user,free);  
            }  
        }  
    }  
}  

//总经理 
public class GeneralHandler extends ConsumeHandler {  
    @Override  
    public void doHandler(String user, double free) {  
        if (free>=1000){  
            if (user.equals("lwxzy")) {  
                System.out.println("给予报销:" + free);  
            } else {  
                System.out.println("报销不通过");  
            }  
        }else{  
            if (getNextHandler()!=null){  
                getNextHandler().doHandler(user,free);  
            }  
        }  
    }  
}  

public class ChainOfResponsibilityActivity extends AppCompatActivity {  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_chain_of_responsibility);  
  
        ProjectHandler projectHandler=new ProjectHandler();  
        DeptHandler deptHandler=new DeptHandler();  
        GeneralHandler generalHandler=new GeneralHandler();  
  
        projectHandler.setNextHandler(deptHandler);  
        deptHandler.setNextHandler(generalHandler);  
  
        projectHandler.doHandler("lwx",450);  
        projectHandler.doHandler("lwx", 600);  
        projectHandler.doHandler("zy", 600);  
        projectHandler.doHandler("zy", 1500);  
        projectHandler.doHandler("lwxzy", 1500);  
    }  
}