Apache HttpClient 响应内容长度返回 -1

为什么下面的代码返回-1？看来请求失败了。

public static void main(String[] args)
{
    DefaultHttpClient httpClient = new DefaultHttpClient();
    HttpGet httpGet = new HttpGet("http://www.google.de");

    HttpResponse response;
    try
    {
        response = httpClient.execute(httpGet);
        HttpEntity entity = response.getEntity();
        EntityUtils.consume(entity);

        // Prints -1
        System.out.println(entity.getContentLength());
    }
    catch (ClientProtocolException e)
    {
        e.printStackTrace();
    }
    catch (IOException e)
    {
        e.printStackTrace();
    }
    finally
    {
        httpGet.releaseConnection();
    }
}

是否可以得到字符串形式的响应？

尝试跑步

Header[] headers = response.getAllHeaders();
for (Header header : headers) {
    System.out.println(header);
}

它将打印

Date: Tue, 10 Sep 2013 19:10:04 GMT
Expires: -1
Cache-Control: private, max-age=0
Content-Type: text/html; charset=ISO-8859-1
Set-Cookie: PREF=ID=dad7e2356ddb3b7a:FF=0:TM=1378840204:LM=1378840204:S=vQcLzVPbOOTxfvL4; expires=Thu, 10-Sep-2015 19:10:04 GMT; path=/; domain=.google.de
Set-Cookie: NID=67=S11HcqAV454IGRGMRo-AJpxAPxClJeRs4DRkAJQ5vI3YBh4anN3qS0EVeiYX_4XDTGN-mY86xTBoJ3Ncca7eNSdtGjcaG31pbCOuqsZEQMWwKn-7-6Dnizx395snehdA; expires=Wed, 12-Mar-2014 19:10:04 GMT; path=/; domain=.google.de; HttpOnly
P3P: CP="This is not a P3P policy! See http://www.google.com/support/accounts/bin/answer.py?hl=en&answer=151657 for more info."
Server: gws
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Alternate-Protocol: 80:quic
Transfer-Encoding: chunked

这不是问题，您请求的页面根本没有提供Content-Length其响应中的标头。因此，HttpEntity#getContentLength()回报-1.

EntityUtils http://hc.apache.org/httpcomponents-core-4.2.x/httpcore/apidocs/org/apache/http/util/EntityUtils.html有许多方法，其中一些返回一个String.

Running curl最近生产

> curl --head http://www.google.de
HTTP/1.1 200 OK
Date: Fri, 03 Apr 2020 15:38:18 GMT
Expires: -1
Cache-Control: private, max-age=0
Content-Type: text/html; charset=ISO-8859-1
P3P: CP="This is not a P3P policy! See g.co/p3phelp for more info."
Server: gws
X-XSS-Protection: 0
X-Frame-Options: SAMEORIGIN
Set-Cookie: 1P_JAR=2020-04-03-15; expires=Sun, 03-May-2020 15:38:18 GMT; path=/; domain=.google.de; Secure
Set-Cookie: NID=201=H8GdKY8_vE5Ehy6qSkmQru13HqdGEj2tvZUFqvTDAVBxFoL4POI0swPtfI45v1TBjrJuAAfbcNMUddniIf9HHituCAFwUqmUFMDwxDYK5qUlcWiB1A64OcGp6PTT6LKur2r_3z-ToSvLf8RZhKWdny6E8SaArMpkaOqUEWp4aoQ; expires=Sat, 03-Oct-2020 15:38:18 GMT; path=/; domain=.google.de; HttpOnly
Transfer-Encoding: chunked
Accept-Ranges: none
Vary: Accept-Encoding

标头包含一个Transfer-Encoding的价值chunked. With chunked https://www.rfc-editor.org/rfc/rfc2616#section-3.6，响应包含“块”，前面带有它们的长度。 HTTP 客户端使用它们来读取整个响应。

The HTTP 规范状态 https://www.rfc-editor.org/rfc/rfc2616#page-33认为Content-Length标头不应出现在以下情况：Transfer-Encoding值为chunked如果是，则必须忽略。