目录

 

1.简介

2.优点

3.缺点

4.形式

---

1.简介

通过将这些对象连成一条链，并沿着这条链传递该请求，直到所有对象处理它为止。这样每个对象都会有机会处理请求，从而也就避免了请求的发送者和接收者之间的耦合关系。

2.优点

将请求和处理分开，两者解耦，提高系统的灵活性。

3.缺点

当链较长时，常常会引发两个问题。性能问题和调试问题，每个请求都从头遍历到尾，可想而知。

4.形式

抽象处理类

public abstract class AHandler {
    private AHandler nextHandler;

    public final Response handleMessage(Request request) {
        Response response = null;
        if(this.getHandlerLevel().equals(request.getRequestLevel())) {
            response = this.echo(request);
        }else {
            if(this.nextHandler != null) {
                response = this.nextHandler.handlerMessage(request);
            }else {
                System.out.prontln("没有后继处理者，另行处理");
            }
        }
        return response;
    }

    public void setNext(AHandler _handler) {
        this.nextHandler = _handler;
    }

    protected abstract Level getHandlerLevel();
    protected abstract Response echo(Request request);
}

具体处理类

public class Handler1 extends AHandler {
    protected Response echo(Request request) {
        System.out.println("完成处理逻辑");
        return null;
    }
    protected Level getHandlerLevel() {
        System.out.println("设置处理级别");
        return null;
    }
}

public class Handler2 extends AHandler {
    protected Response echo(Request request) {
        System.out.println("完成处理逻辑");
        return null;
    }
    protected Level getHandlerLevel() {
        System.out.println("设置处理级别");
        return null;
    }
}

public class Handler3 extends AHandler {
    protected Response echo(Request request) {
        System.out.println("完成处理逻辑");
        return null;
    }
    protected Level getHandlerLevel() {
        System.out.println("设置处理级别");
        return null;
    }
}

级别类

public class Level {
    System.out.println("请求和处理级别");
}

请求类

public class Request {
    System.out.println("封装请求");
    public Level getRequestLevel() {
        System.out.println("获取请求级别");
        return null;
    }
}

回复类

public class Response {
    Sytem.out.println("封装返回的结果");
}

测试类

public class Test {
    public static void main(String[] args) {
        AHandler handler1 = new Handler1();
        AHandler handler2 = new Handler2();
        AHandler handler3 = new Handler3();
        handler1.setNext(handler2);
        handler2.setNext(handler3);
        Reponse reponse = handler1.handlerMessage(new Request());
    }
}