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