设计模式---职责链模式

职责链模式：

     使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合。将这些对象连成一条链，沿着这条链传递该请求，直到有一个对象处理为止。

public abstract class Handler {
    protected Handler handler;

    public void setHandler(Handler handler) {
        this.handler = handler;
    }

    public abstract void handlerRequest(int stamp);
}

public class Handler_A extends Handler{
    @Override
    public void handlerRequest(int stamp) {
        if (stamp >= 0 && stamp < 5) {
            System.out.println(this.getClass().getName() + "，处理：" + stamp);
        } else if (handler != null) {
            handler.handlerRequest(stamp);
        }
    }
}

public class Handler_B extends Handler {
    @Override
    public void handlerRequest(int stamp) {
        if (stamp > 5) {
            System.out.println(this.getClass().getName() + "，处理：" + stamp);
        } else if (handler != null) {
            handler.handlerRequest(stamp);
        }
    }
}

public class ChainDemo {
    public static void main(String[] args) {
        Handler handlerA = new Handler_A();
        Handler handlerB = new Handler_B();
        handlerA.setHandler(handlerB);

        int[] stamps = {0, 1, 3, 5, 9, 11, 15};

        for (int stamp : stamps) {
            handlerA.handlerRequest(stamp);
        }
    }
}

javax.servlet.Filter

javax.servlet.FilterChain