Java设计模式--责任链模式

该模式将多个接收者连成链，当请求来临时，沿着责任链匹配接受者，直到有对象接受为止，对请求者和接收者进行了充分的解耦。简单实现：

抽象类：

public abstract class Handler {
    public Handler next;

    public abstract void handleRequest(String condition);

    public void setNext(Handler handler){
        next = handler;
    };
}

实现类

public class HandlerImpl1 extends Handler{
    public static final String CONDITION = "HandlerImpl1";

    @Override
    public void handleRequest(String condition) {
        if (CONDITION.equals(condition)){
            System.out.println("HandlerImpl1 handle");
        }else{
            if(next != null)
                next.handleRequest(condition);
        }
    }
}

public class HandlerImpl2 extends Handler{
    public static final String CONDITION = "HandlerImpl2";

    @Override
    public void handleRequest(String condition) {
        if (CONDITION.equals(condition)){
            System.out.println("HandlerImpl2 handle");
        }else{
            if(next != null)
                next.handleRequest(condition);
        }
    }
}

public class HandlerImpl3 extends Handler{
    public static final String CONDITION = "HandlerImpl3";

    @Override
    public void handleRequest(String condition) {
        if (CONDITION.equals(condition)){
            System.out.println("HandlerImpl3 handle");
        }else{
            if(next != null)
                next.handleRequest(condition);
        }
    }
}

测试类·

public class test {

    public static void main(String[] args) {
        HandlerImpl1 handlerImpl1 = new HandlerImpl1();
        HandlerImpl2 handlerImpl2 = new HandlerImpl2();
        HandlerImpl3 handlerImpl3 = new HandlerImpl3();
        handlerImpl1.setNext(handlerImpl2);
        handlerImpl2.setNext(handlerImpl3);

        handlerImpl1.handleRequest("HandlerImpl2");
    }

}