Apache HttpClient 未显示响应的 Content-Length 和 Content-Encoding 标头 [英] Apache HttpClient is not showing Content-Length and Content-Encoding headers of the response

问题描述

我安装了 Apache httpcomponents-client-5.0.x 在查看 http 响应的标头时，我感到震惊的是它没有显示 Content-Length 和 Content-Encoding 标头，这是我使用的代码测试

I installed Apache httpcomponents-client-5.0.x and while reviewing the headers of the http response, I was shocked it doesn't show the Content-Length and Content-Encoding headers, this is the code I used for testing

import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import com.sun.net.httpserver.Headers;

CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet request = new HttpGet(new URI("https://www.example.com"));
CloseableHttpResponse response = httpclient.execute(request);
Header[] responseHeaders = response.getHeaders();
for(Header header: responseHeaders) {               
    System.out.println(header.getName());
}
// this prints all the headers except 
// status code header
// Content-Length
// Content-Encoding

无论我尝试什么，我都会得到相同的结果，就像这样

No matter what I try I get the same result, like this

Iterator<Header> headersItr = response.headerIterator();
while(headersItr.hasNext()) {
    Header header = headersItr.next();
    System.out.println(header.getName());
}

或者这个

HttpEntity entity = response.getEntity();
System.out.println(entity.getContentEncoding()); // NULL
System.out.println(entity.getContentLength());   // -1

根据 6 年前提出的这个问题，即使使用旧版本的 Apache HttpClient，这似乎也是一个老问题.

According to this question that has been asked 6 years ago, it seems like an old issue even with older versions of Apache HttpClient.

当然，服务器实际上正在返回 Wireshark 确认的那些标头，并且 Apache HttpClient 会自行记录

Of-course the server is actually returning those headers as confirmed by Wireshark, and Apache HttpClient logs itself

2020-04-03 07:59:09,106 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << HTTP/1.1 200 OK
2020-04-03 07:59:09,106 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Content-Encoding: gzip
2020-04-03 07:59:09,106 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Accept-Ranges: bytes
2020-04-03 07:59:09,107 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Age: 451956
2020-04-03 07:59:09,107 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Cache-Control: max-age=604800
2020-04-03 07:59:09,107 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Content-Type: text/html; charset=UTF-8
2020-04-03 07:59:09,107 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Date: Fri, 03 Apr 2020 05:59:09 GMT
2020-04-03 07:59:09,108 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Etag: "3147526947+gzip"
2020-04-03 07:59:09,108 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Expires: Fri, 10 Apr 2020 05:59:09 GMT
2020-04-03 07:59:09,108 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Last-Modified: Thu, 17 Oct 2019 07:18:26 GMT
2020-04-03 07:59:09,108 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Server: ECS (dcb/7EEB)
2020-04-03 07:59:09,108 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Vary: Accept-Encoding
2020-04-03 07:59:09,109 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << X-Cache: HIT
2020-04-03 07:59:09,109 DEBUG [org.apache.hc.client5.http.headers] http-outgoing-0 << Content-Length: 648

顺便说一句，java.net.http 库，称为 JDK HttpClient 运行良好并显示所有标题.

BTW, java.net.http library known as JDK HttpClient works great and show all the headers.

是我做错了什么，还是我应该报告一个存在多年的错误?

Is there something wrong I did, or should I report a bug that been there for years ?

推荐答案

HttpComponents committer here...

HttpComponents committer here...

您没有密切注意 Dave G 所说的话.默认情况下，HttpClientBuilder 将启用透明解压，并且您不再看到某些标头的原因是 这里:

You did not closely pay attention what Dave G said. By default, HttpClientBuilder will enable transparent decompression and the reason why you don't see some headers anymore is here:

if (decoderFactory != null) {
  response.setEntity(new DecompressingEntity(response.getEntity(), decoderFactory));
  response.removeHeaders(HttpHeaders.CONTENT_LENGTH);
  response.removeHeaders(HttpHeaders.CONTENT_ENCODING);
  response.removeHeaders(HttpHeaders.CONTENT_MD5);
} ...

对于JDK HttpClient，它不会进行任何透明的解压，因此您可以看到压缩流的长度.必须自己解压.

Regarding the JDK HttpClient, it will not perform any transparent decompression, therefore you see the length of the compressed stream. You have to decompress on your own.

在这里卷曲提交者...

curl committer here...

我也提出了一个问题.

这篇关于Apache HttpClient 未显示响应的 Content-Length 和 Content-Encoding 标头的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！