The target server failed to respond 错误解决

一个很正常的网站，使用httpclient提交怎么都会有问题

　　　　　HttpPost httppost = new HttpPost();
        // HttpGet httppost = new HttpGet();
        URI uri = new URI(post);
        httppost.setURI(uri);
        HttpClient httpclient = new DefaultHttpClient();
        String html = "";
        HttpResponse response = httpclient.execute(httppost);
        System.out.println(response.getStatusLine());

总是报那个错误org.apache.http.NoHttpResponseException:

　　　　　　　　　　　　　　　　　　　　　　　　The target server failed to respond

本来打算读读源码看看到底什么问题，突然想把post换成get方式再试试，结果完全无问题了。。。。哪位有兴趣读了源码可以告诉我下原因