Java设计模式-----Visitor访问者模式

    源自：

    Chain of Responsibility职责链模式：

    为了避免请求的发送者和接收者之间的耦合关系，使多个接受对象都有机会处理请求。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

    例子：

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    public class Boy {

        private boolean hasCar; // 是否有车
        private boolean hasHouse; // 是否有房
        private boolean hasResponsibility; // 是否有责任心

        public Boy() {
        }

        public Boy(boolean hasCar, boolean hasHouse, boolean hasResponsibility) {
            this.hasCar = hasCar;
            this.hasHouse = hasHouse;
            this.hasResponsibility = hasResponsibility;
        }

        public boolean isHasCar() {
            return hasCar;
        }

        public void setHasCar(boolean hasCar) {
            this.hasCar = hasCar;
        }

        public boolean isHasHouse() {
            return hasHouse;
        }

        public void setHasHouse(boolean hasHouse) {
            this.hasHouse = hasHouse;
        }

        public boolean isHasResponsibility() {
            return hasResponsibility;
        }

        public void setHasResponsibility(boolean hasResponsibility) {
            this.hasResponsibility = hasResponsibility;
        }
    }

    public interface Handler {
         public void handleRequest(Boy boy);
    }

    public class HouseHandler implements Handler {

        private Handler handler;

        public HouseHandler(Handler handler) {

            this.handler = handler;
        }

        public Handler getHandler() {
            return handler;
        }

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

        public void handleRequest(Boy boy) {
            if (boy.isHasHouse()) {
                System.out.println("没想到吧，我还有房子");
            } else {
                System.out.println("我也没有房");
                handler.handleRequest(boy);
            }
        }
    }

    public class CarHandler implements Handler {

        private Handler handler;

        public CarHandler(Handler handler) {
            this.handler = handler;
        }

        public Handler getHandler() {
            return handler;
        }

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

        public void handleRequest(Boy boy) {
            if (boy.isHasCar()) {
                System.out.println("呵呵，我有辆车");
            } else {
                System.out.println("我没有车");
                handler.handleRequest(boy);
            }
        }
    }

    public class ResponsibilityHandler implements Handler {

        private Handler handler;

        public ResponsibilityHandler(Handler handler) {
            this.handler = handler;
        }

        public Handler getHandler() {
            return handler;
        }

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

        public void handleRequest(Boy boy) {
            if (boy.isHasResponsibility()) {
                System.out.println("我只有一颗带Responsibility的心");
            } else {
                System.out.println("更没有责任心");
                handler.handleRequest(boy);
            }
        }
    }

    public class Girl {

        public static void main(String[] args) {

            Boy boy = new Boy(false, false, true);// 这个boy没有车，也没有房，不过很有责任心
            Handler handler = new CarHandler(new HouseHandler(
                    new ResponsibilityHandler(null)));// 也可以使用setHanlder方法
            handler.handleRequest(boy);
        }
    }

【责编:landy】

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