设计模式学习_03责任链模式

1、责任链模式介绍:

责任链模式是行为型设计模式之一;

2、责任链模式的定义:

使多个对象都有机会处理请求, 从而避免了请求的发送者和接收者之间的耦合关系, 将这些对象连成一条链, 并沿着这条链传递该请求, 直到有对象处理它为止;

3、责任链模式的使用场景:

(1) 多个对象可以处理同一请求, 但具体由哪个对象处理则在运行时动态决定;
  (2) 在请求处理者不明确的情况下向多个对象中的一个提交一个请求;
  (3) 需要动态指定一组对象处理请求;

4、示例代码:

public abstract class Leader {
    protected Leader nextHandler;
    public final void handleRequest(int money) {
        if (money <= limit) {
            handle(money);
        } else {
            if (null != nextHandler){
                nextHandler.handleRequest(money);
            }
        }
    }
    public abstract int limit();
    public abstract void handle(int money);
}

public class GroupLeader extends Leader {
    @Override
    public int limit() {
        return 1000;
    }
    @Override
    public void handle(int money) {
        System.out.println("组长批复报销" + money + "元");
    }
}

public class Director extends Leader {
    @Override
    public int limit() {
        return 5000;
    }
    @Override 
    public void handle(int money) {
        System.out.println("主管批复报销" + money + "元");
    }
}

public class Manager extends Leader {
    @Override
    public int limit() {
        return 10000;
    }
    @Override
    public void handle(int money) {
        System.out.println("经理批复报销" + money + "元");
    }
}
public class Boss extends Leader {
    @Override
    public int limit() {
        return Integer.MAX_VALUE;
    }
    @Override
    public void handle(int money) {
        System.out.println("老板批复报销" + money + "元");
    }
}

public class XiaoMin {
    public static void main(String[] args) {
        GroupLeader groupLeander = new GroupLeader();
        Director director = new Director();
        Manager manager = new Manager();
        Boss boss = new Boss();
        nextHandler.handle = director;
        director.handle = manager;
        manager.handle = boss;
        groupLeander.handleRequest(50000);
    }
}

5、优缺点: