Java设计模式之责任链模式详解

public class LeaveRequest {
    private String name;//姓名
    private int num;//请假天数
    private String content;//请假内容
    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;
    }
}

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;
    //该领导处理的请假天数区间
    private int numStart;
    private int numEnd;
    //领导上面还有领导
    private Handler nextHandler;
    //设置请假天数范围 上不封顶
    public Handler(int numStart) {
        this.numStart = numStart;
    }
    //设置请假天数范围
    public Handler(int numStart, int numEnd) {
        this.numStart = numStart;
        this.numEnd = numEnd;
    }
    //设置上级领导
    public void setNextHandler(Handler nextHandler){
        this.nextHandler = nextHandler;
    }
    //提交请假条
    public final void submit(LeaveRequest leave){
        if(0 == this.numStart){
            return;
        }
        //如果请假天数达到该领导者的处理要求
        if(leave.getNum() >= this.numStart){
            this.handleLeave(leave);
            //如果还有上级 并且请假天数超过了当前领导的处理范围
            if(null != this.nextHandler && leave.getNum() > numEnd){
                this.nextHandler.submit(leave);//继续提交
            } else {
                System.out.println("流程结束");
            }
        }
    }
    //各级领导处理请假条方法
    protected abstract void handleLeave(LeaveRequest leave);
}

public class Counselor extends Handler {
    public Counselor() {
        //辅导员 处理1-3天的请假
        super(Handler.NUM_ONE, Handler.NUM_THREE);
    }
    @Override
    protected void handleLeave(LeaveRequest leave) {
        System.out.println(leave.getName() + "请假" + leave.getNum() + "天," + leave.getContent() + "。");
        System.out.println("辅导员审批：同意。");
        //也可以在这里设置下一个链路处理的handler
        //setNextHandler(new Dean());
    }
}
public class Dean extends Handler {
    public Dean() {
        //院长处理3-7天的请假
        super(Handler.NUM_THREE, Handler.NUM_SEVEN);
    }
    @Override
    protected void handleLeave(LeaveRequest leave) {
        System.out.println(leave.getName() + "请假" + leave.getNum() + "天," + leave.getContent() + "。");
        System.out.println("院长审批：同意。");
        //也可以在这里设置下一个链路处理的handler
        //setNextHandler(new CollegeSecretary ());
    }
}
public class CollegeSecretary extends Handler {
    public CollegeSecretary() {
        //学院书记处理7天以上的请假
        super(Handler.NUM_SEVEN);
    }
    @Override
    protected void handleLeave(LeaveRequest leave) {
        System.out.println(leave.getName() + "请假" + leave.getNum() + "天," + leave.getContent() + "。");
        System.out.println("学院书记审批：同意。");
        //也可以在这里设置下一个链路处理的handler
        //setNextHandler(null); //最后一个
    }
}

public class TestClient {
    public static void main(String[] args) {
        //请假条来一张
        LeaveRequest leave = new LeaveRequest("kaico",8,"身体不适");
        //各级领导
        Counselor counselor= new Counselor();
        //如果前面handleLeave 方法中设置了下一个handler，这里就不需要了，直接提交申请就好了
        Dean dean = new Dean();
        CollegeSecretary collegeSecretary = new CollegeSecretary();
        counselor.setNextHandler(dean);//辅导员的领导是院长
        dean.setNextHandler(collegeSecretary);//院长的领导是学院书记
        //提交申请
        counselor.submit(leave);
    }
}