设计模式 - java有关装饰器的重构

Question

之前写过一个服务器程序, 大概2000多行吧, 最近看到了发现写的太烂了, 就想着重构一下, 现在有4个接口与4个类, 分别是Request接口,Response接口,HttpRequest接口,HttpResponse接口以及相应的实现类DefaultRequest和DefaultResponse, DefaultHttpRequest和DefaultResponse接口.
类图大概是这样子的:

我的DefaultHttpRequest/DefaultHttpResponse是通过装饰器模式持有一个DefaultRequest/DefaultResponse来完成Request,ServletRequest/Response,ServletResponse接口的功能. 然后自己实现HttpRequest,HttpServletRequest/HttpResponse,HttpServletResponse接口的功能;

Response接口中有一个getRequest()和setRequest()方法
HttpResponse接口中有一个getHttpRequest()和setHttpRequest()方法.
这几个方法用于Request和Response进行通讯使用.

但是这就出现了一个问题:
DefaultHttpResponse的getHttpRequest()和getRequest()如果想要返回的httpRquest所持有的request和request是同一个的话, 就需要外部环境来保证, 所以我写的代码是这样的:

//request和response是由其他类解析http请求传递进来的
DefaultHttpRequest defaultRequest = new DefaultHttpRequest(request) ;
DefaultHttpResponse defaultHttpResponse = new DefaultHttpResponse(response) ;
defaultHttpResponse.setRequest(request) ;
defaultHttpResponse.setHttpRequest(defaultRequest) ;

但是我总觉着这样写, 似乎破坏了封装性, 但是不知道该怎么改?

Answer 1

You mean defaultHttpResponse.setRequest() 和 defaultHttpResponse.setHttpRequest() 的参数是有紧密联系的，这种情况你可以只保留一个 set 接口，就是 setRequest，提供一个 get 接口，getDefaultRequest(), probably like this

class DefaultHttpResponse {
    private HttpRequest request;
    private DefaultHttpRequest defaultRequest;

    public void setRequest(HttpRequest request) {
        this.request = request;
        defaultRequest = new DefaultHttpRequest(request);
    }

    public HttpDefaultReqeust getDefaultRequest() {
        return defaultRequest;
    }
}

Can also be guaranteed through mutual exclusion

class DefaultHttpResponse {
    private HttpRequest request;
    private DefaultHttpRequest defaultRequest;

    public void setRequest(HttpRequest request) {
        if (defaultRequest != null) {
            throw new RuntimeException();
        }
        this.request = request;
        defaultRequest = new DefaultHttpRequest(request);
    }

    public void setDefaultRequest(DefaultHttpRequest defaultRequest) {
        if (request != null) {
            throw new RuntimeException();
        }
        this.defaultReqeust = defaultRequst;
        request = defaultRequest.getRequest();
    }
}

or consistency check

class DefaultHttpResponse {
    private HttpRequest request;
    private DefaultHttpRequest defaultRequest;

    public void setRequest(HttpRequest request) {
        if (defaultReqeust != null && defaultReqeust.getRequest() != request) {
            throw new RuntimeException();
        }
        this.request = request;
    }

    public void setDefaultRequest(DefaultHttpRequest defaultRequest) {
        if (request != null && defaultReqeust.getRequest() != request) {
            throw new RuntimeException();
        }
        this.defaultRequest = defaultRequest;
    }
}