Question

我正在尝试使用cachingHttpClient缓存HTTP响应，但是徒劳无功。这是我通过引用此链接http://hc.apache.org/httpcomponents-client-ga/tutorial/html/caching.html

放在一起的演示

  public class CacheDemo {

    public static void main(String[] args) {
        CacheConfig cacheConfig = new CacheConfig();
        cacheConfig.setMaxCacheEntries(1000);
        cacheConfig.setMaxObjectSizeBytes(1024 * 1024);

        HttpClient cachingClient = new CachingHttpClient(new DefaultHttpClient(), cacheConfig);

        HttpContext localContext = new BasicHttpContext();

        sendRequest(cachingClient, localContext);
        CacheResponseStatus responseStatus = (CacheResponseStatus) localContext.getAttribute(
                CachingHttpClient.CACHE_RESPONSE_STATUS);
        checkResponse(responseStatus);


        sendRequest(cachingClient, localContext);
        responseStatus = (CacheResponseStatus) localContext.getAttribute(
                CachingHttpClient.CACHE_RESPONSE_STATUS);
        checkResponse(responseStatus);
    }

    static void sendRequest(HttpClient cachingClient, HttpContext localContext) {
        HttpGet httpget = new HttpGet("http://www.mydomain.com/content/");
        HttpResponse response = null;
        try {
            response = cachingClient.execute(httpget, localContext);
        } catch (ClientProtocolException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        HttpEntity entity = response.getEntity();
        try {
            EntityUtils.consume(entity);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    static void checkResponse(CacheResponseStatus responseStatus) {
        switch (responseStatus) {
            case CACHE_HIT:
                System.out.println("A response was generated from the cache with no requests "
                        + "sent upstream");
                break;
            case CACHE_MODULE_RESPONSE:
                System.out.println("The response was generated directly by the caching module");
                break;
            case CACHE_MISS:
                System.out.println("The response came from an upstream server");
                break;
            case VALIDATED:
                System.out.println("The response was generated from the cache after validating "
                        + "the entry with the origin server");
                break;
        }
    }

  }

这是一个简单的程序，但我无法弄清楚我哪里出错了。非常感谢您的帮助。感谢。

Answer 1

使用网址http://www.mydomain.com/content/的GET请求最终将使用Http 404代码（未找到）。这个结果很可能不会被高速缓存，所以这就是为什么它对我不起作用的原因。

<强>更新必须满足某些条件才能从缓存中提供响应。您应该启用apache http客户端的日志记录（例如http://hc.apache.org/httpclient-3.x/logging.html）。您可以调试正在进行的操作以及为什么您的其他URL存在缓存未命中。您可能应该下载该库的源代码并查看（http://hc.apache.org/downloads.cgi）。特别是你会对org.apache.http.impl.client.cache.CachedResponseSuitabilityChecker课感兴趣。这也可以帮助您进行以下的库开发。

顺便说一下。 http://muvireviews.com/celebrity/full_view/41/Shahrukh-khan返回此标题：

Cache-Control:no-store, no-cache, must-revalidate, post-check=0, pre-check=0, max-age=0, no-cache, no-store

并且由于CachedResponseSuitabilityChecker中的if语句：

            if (HeaderConstants.CACHE_CONTROL_NO_CACHE.equals(elt.getName())) {
                log.trace("Response contained NO CACHE directive, cache was not suitable");
                return false;
            }

不会使用缓存。

祝你好运;）

Answer 2

默认情况下，CachingHttpClient假设共享缓存，因此如果响应头包含＆＃34; Cache-Control：private＆＃34;它将忽略存储。（在你的情况下，我认为就是这种情况）。请参阅@ https://hc.apache.org/httpcomponents-client-ga/tutorial/html/caching.html（第6.4节配置）

尝试将其关闭，以便能够在仅客户端模式下使用，即

CacheConfig cacheConfig = new CacheConfig();
cacheConfig.setMaxCacheEntries(1000);
cacheConfig.setMaxObjectSizeBytes(1024 * 1024);
cacheConfig .setSharedCache(false); // Turn it OFF here

这对我有用。祝你好运!!!

无法在java中使用cachingHttpClient缓存HttpResponse？

2 个答案: