JAVA设计模式之【职责链模式】

职责链模式
	专门处理请求链式传递的模式
	角色
		Handler抽象处理者
		ConcreteHandler具体处理者
	在职责链模式中，很多对象由每一个对象对其下家的引用而连接成一条链，请求在这条链上传递，直到链上的某一个对象决定处理次请求。
	具体处理类的作用。
		1.处理请求，handleRequest。
		2.转发请求，如果该请求超出了当前处理类的权限，可以转发给下家。

看例子，批复休假

1.休假请求类

package CoR;

/**
 * Created by Jiqing on 2016/10/22.
 */
public class LeaveRequest // 休假请求
{
    private String leaveName; // 休假人
    private int leaveDays; // 休假天数

    public LeaveRequest(String leaveName,int leaveDays)
    {
        this.leaveName=leaveName;
        this.leaveDays=leaveDays;
    }

    public void setLeaveName(String leaveName) {
        this.leaveName = leaveName;
    }

    public void setLeaveDays(int leaveDays) {
        this.leaveDays = leaveDays;
    }

    public String getLeaveName() {
        return (this.leaveName);
    }

    public int getLeaveDays() {
        return (this.leaveDays);
    }
}

2.抽象处理类

public abstract class Leader // 抽象处理者
{
	protected String name;
	protected Leader successor;
	public Leader(String name)
	{
		this.name=name;
	}
	public void setSuccessor(Leader successor) 
	{ // 设置下一个处理者
		this.successor=successor;
	}
	public abstract void handleRequest(LeaveRequest request); // 处理请求
}

3.主任

package CoR;

/**
 * Created by Jiqing on 2016/10/22.
 */
public class Director extends Leader // 主任
{
    public Director(String name)
    {
        super(name);
    }
    public void handleRequest(LeaveRequest request)
    {
        if(request.getLeaveDays()<3) // 小于三天主任审批
        {
            System.out.println("主任" + name + "审批员工" + request.getLeaveName() + "的请假条，请假天数为" + request.getLeaveDays() + "天。");
        }
        else
        {
            if(this.successor!=null)
            {
                this.successor.handleRequest(request);
            }
        }
    }
}

4.经理

package CoR;

/**
 * Created by Jiqing on 2016/10/22.
 */
public class Manager extends Leader // 经理审批
{
    public Manager(String name)
    {
        super(name);
    }
    public void handleRequest(LeaveRequest request)
    {
        if(request.getLeaveDays()<10)
        {
            System.out.println("经理" + name + "审批员工" + request.getLeaveName() + "的请假条，请假天数为" + request.getLeaveDays() + "天。");
        }
        else
        {
            if(this.successor!=null)
            {
                this.successor.handleRequest(request);
            }
        }
    }
}

5.副总经理

package CoR;

/**
 * Created by Jiqing on 2016/10/22.
 */
public class ViceGeneralManager extends Leader // 副总经理
{
    public ViceGeneralManager(String name)
    {
        super(name);
    }
    public void handleRequest(LeaveRequest request)
    {
        if(request.getLeaveDays()<20)
        {
            System.out.println("副总经理" + name + "审批员工" + request.getLeaveName() + "的请假条，请假天数为" + request.getLeaveDays() + "天。");
        }
        else
        {
            if(this.successor!=null)
            {
                this.successor.handleRequest(request);
            }
        }
    }
}

6.总经理

package CoR;

/**
 * Created by Jiqing on 2016/10/22.
 */
public class GeneralManager extends Leader // 总经理审批
{
    public GeneralManager(String name)
    {
        super(name);
    }

    public void handleRequest(LeaveRequest request)
    {
        if(request.getLeaveDays()<30)
        {
            System.out.println("总经理" + name + "审批员工" + request.getLeaveName() + "的请假条，请假天数为" + request.getLeaveDays() + "天。");
        }
        else
        {
            System.out.println("莫非" + request.getLeaveName() + "想辞职，居然请假" + request.getLeaveDays() + "天。");
        }
    }
}

7.客户端

package CoR;

/**
 * Created by Jiqing on 2016/10/22.
 */
public class Client
{
    public static void main(String args[])
    {
        Leader objDirector,objManager,objGeneralManager,objViceGeneralManager;

        objDirector=new Director("王明");
        objManager=new Manager("赵强");
        objGeneralManager=new GeneralManager("李波");
        objViceGeneralManager=new ViceGeneralManager("肖红");

        // 建立职责链
        objDirector.setSuccessor(objManager); // 主任上级是经理
        objManager.setSuccessor(objViceGeneralManager); // 经理上级是副经理
        objViceGeneralManager.setSuccessor(objGeneralManager); // 副经理上级是总经理

        LeaveRequest lr1=new LeaveRequest("张三",2);
        objDirector.handleRequest(lr1);

        LeaveRequest lr2=new LeaveRequest("李四",5);
        objDirector.handleRequest(lr2);

        LeaveRequest lr3=new LeaveRequest("王五",15);
        objDirector.handleRequest(lr3);

        LeaveRequest lr4=new LeaveRequest("赵六",25);
        objDirector.handleRequest(lr4);
    }
}

亮点就在职责链上。

看结果：
主任王明审批员工张三的请假条，请假天数为2天。
经理赵强审批员工李四的请假条，请假天数为5天。
副总经理肖红审批员工王五的请假条，请假天数为15天。
总经理李波审批员工赵六的请假条，请假天数为25天。