大话设计模式-职责链模式

UML

定义一个处理请示的接口

/** * 定义一个处理请示的接口 */
public class Handler {
    /** * 继任者 */
    protected Handler successor;

    /** * 设置继任者 * * @param successor 继任者 */
    public void setSuccessor(Handler successor) {
        this.successor = successor;
    }

    /** * 处理请求 */
    public void HandleRequest(int request) {
    }
}

具体的处理请求的类1

/** * 具体的处理请求的类1 * 只能处理request为1-10的请求 */
public class ConcreteHandler1 extends Handler {
    @Override
    public void HandleRequest(int request) {
        if (request >= 0 && request < 10) {
            System.out.println("ConcreteHandler1 处理了请求" + request);
        } else if (successor != null) {
            successor.HandleRequest(request);
        }
    }
}

具体的处理请求的类2

/** * 具体的处理请求的类2 * 只能处理request为10-20的请求 */
public class ConcreteHandler2 extends Handler {
    @Override
    public void HandleRequest(int request) {
        if (request >= 10 && request < 20) {
            System.out.println("ConcreteHandler2 处理了请求" + request);
        } else if (successor != null) {
            successor.HandleRequest(request);
        }
    }
}

具体的处理请求的类3

/** * 具体的处理请求的类3 * 只能处理request为20-30的请求 */
public class ConcreteHandler3 extends Handler {
    @Override
    public void HandleRequest(int request) {
        if (request >= 20 && request < 30) {
            System.out.println("ConcreteHandler3 处理了请求" + request);
        } else if (successor != null) {
            successor.HandleRequest(request);
        }
    }
}

测试类

/** * 测试类 */
public class Main {
    public static void main(String[] args) {
        Handler h1 = new ConcreteHandler1();
        Handler h2 = new ConcreteHandler2();
        Handler h3 = new ConcreteHandler3();
        h1.setSuccessor(h2);
        h2.setSuccessor(h3);

        int[] requests = {1, 2, 3, 11, 12, 13, 21, 22, 23, 99};
        for (int request : requests) {
            h1.HandleRequest(request);
        }
    }
}

运行结果