Java设计模式<责任链>

Java设计模式<责任链>

意图

• 避免请求发送者与接收者耦合在一起，让多个对象都有可能接收请求，将这些对象连接成一条链，并且沿着这条链传递请求，直到有对象处理它为止

场景

• 处理消息的时候以过滤很多道

优点

• 降低耦合度。它将请求的发送者和接收者解耦
• 简化了对象。使得对象不需要知道链的结构
• 增强给对象指派职责的灵活性。通过改变链内的成员或者调动它们的次序，允许动态地新增或者删除责任
• 增加新的请求处理类很方便

现实场景举例

JavaDemo

审批人接口

public abstract class Worker {

    protected Worker worker;

    public abstract void permit();

    public Worker setNext(Worker next){
        this.worker = next;
        return next;
    }


}

Team Leader

public class TLWorker extends Worker{
    public void permit() {

        System.err.println("i am the TL ,I have permitted ");

        if(worker != null){
            worker.permit();
        }
    }
}

PM

public class PMWorker extends Worker {
    public void permit() {

        System.err.println("i am the PM ,I have permitted ");
        if(worker != null){
            worker.permit();
        }
    }
}

CEO

public class CEOWorker extends Worker {

    public void permit() {

        System.err.println("i am the CEO ,I have permitted ");
        if(worker != null){
            worker.permit();
        }
    }
}

测试类

public class DemoMain {

    public static void main(String[] args) {
        CEOWorker ceoWorker = new CEOWorker();
        PMWorker pmWorker = new PMWorker();
        TLWorker tlWorker = new TLWorker();
        tlWorker.setNext(pmWorker).setNext(ceoWorker);
        tlWorker.permit();
    }
}

输出

i am the TL ,I have permitted 
i am the PM ,I have permitted 
i am the CEO ,I have permitted