设计模式 行为型模式 -- 职责链模式（定义、结构、纯与不纯的职责链模、具体案例）

分析：

• 抽象处理者（Handler）角色：定义一个处理请求的接口，包含抽象处理方法和一个后继连接。
• 具体处理者（Concrete Handler）角色：实现抽象处理者的处理方法，判断能否处理本次请求，如果可以处理请求则处理，否则将该请求转给它的后继者。
• 客户类（Client）角色：创建处理链，并向链头的具体处理者对象提交请求，它不关心处理细节和请求的传递过程。

现需要开发一个请假流程控制系统。请假一天以下的假只需要小组长同意即可；请假1天到3天的假还需要部门经理同意；请求3天到7天还需要总经理同意才行。

类图：

代码实现：

LeaveRequest.java

package com.tian.responsibility;


public class LeaveRequest {
    //姓名
    private String name;

    //请假天数
    private int num;

    //请假内容
    private String content;

    public LeaveRequest(String name, int num, String content) {
        this.name = name;
        this.num = num;
        this.content = content;
    }

    public String getName() {
        return name;
    }

    public int getNum() {
        return num;
    }

    public String getContent() {
        return content;
    }
}

Handler.java

package com.tian.responsibility;


public abstract class Handler {

    protected final static int NUM_ONE = 1;
    protected final static int NUM_THREE = 3;
    protected final static int NUM_SEVEN = 7;

    //该领导处理的请求天数区间
    private int numStart;
    private int numEnd;

    //声明后续者（声明上级领导）
    private Handler nextHandler;

    public Handler(int numStart) {
        this.numStart = numStart;
    }

    public Handler(int numStart, int numEnd) {
        this.numStart = numStart;
        this.numEnd = numEnd;
    }

    //设置上级领导对象
    public void setNextHandler(Handler nextHandler) {
        this.nextHandler = nextHandler;
    }

    //各级领导处理请求条的方法
    protected abstract void handleLeave(LeaveRequest leave);

    //提交请求条
    public final void submit(LeaveRequest leave) {
        //该领导进行审批
        this.handleLeave(leave);
        if (this.nextHandler != null && leave.getNum() > this.numEnd) {
            //提交给上级领导进行审批
            this.nextHandler.submit(leave);
        } else {
            System.out.println("流程结束！");
        }
    }
}

GeneralManager.java

package com.tian.responsibility;


public class GeneralManager extends Handler {

    public GeneralManager() {
        super(Handler.NUM_THREE, Handler.NUM_SEVEN);
    }

    protected void handleLeave(LeaveRequest leave) {
        System.out.println(leave.getName() + "请假" + leave.getNum() + "天，" + leave.getContent() + "。");
        System.out.println("总经理审批：同意");
    }
}

Manager.java

package com.tian.responsibility;


public class Manager extends Handler {

    public Manager() {
        super(Handler.NUM_ONE, Handler.NUM_THREE);
    }

    protected void handleLeave(LeaveRequest leave) {
        System.out.println(leave.getName() + "请假" + leave.getNum() + "天，" + leave.getContent() + "。");
        System.out.println("部门经理审批：同意");
    }
}

GroupLeader.java

package com.tian.responsibility;


public class GroupLeader extends Handler {

    public GroupLeader() {
        super(0, Handler.NUM_ONE);
    }

    protected void handleLeave(LeaveRequest leave) {
        System.out.println(leave.getName() + "请假" + leave.getNum() + "天，" + leave.getContent() + "。");
        System.out.println("小组长审批：同意");
    }
}

Client.java

package com.tian.responsibility;


public class Client {
    public static void main(String[] args) {
        //创建一个请假条对象
        LeaveRequest leave = new LeaveRequest("小明", 1, "身体不适");

        //创建各级领导对象
        GroupLeader groupLeader = new GroupLeader();
        Manager manager = new Manager();
        GeneralManager generalManager = new GeneralManager();

        //设置处理者链
        groupLeader.setNextHandler(manager);
        manager.setNextHandler(generalManager);

        //小明提交请假申请
        groupLeader.submit(leave);
    }
}

运行结果：