Java 如何在ApacheHttpComponents中向HttpPost添加内容长度头？

我有一个服务器，它期望内容长度作为文章标题的一部分。为了发帖，我正在使用ApacheHttpComponents库

这是预期请求的精简版本（当然包含所有必需的标题）：

我使用了HttpPost的setEntity方法将StringEntity（转换的json->String->StringEntity）设置为帖子的内容。但是当我执行请求时，我最终得到了一个POST请求，它没有在它的头中指定内容长度

是否仍要添加此缺少的标题

（我尝试了setHeader（）来设置内容长度，这抛出了一个错误，表示内容长度已经存在）

这是我用来创建POST请求的代码：

//Convert the registration request object to json
StringEntity registrationRequest_json_entity = new StringEntity(gsonHandle.toJson(registrationRequest));
registrationRequest_json_entity.setContentType("application/json");

//Creating the HttpPost object which contains the endpoint URI
HttpPost httpPost = new HttpPost(Constants.CLIENT_REGISTRATION_URL);
httpPost.setHeader(HTTP.CONTENT_TYPE,"application/json");
httpPost.setHeader("Accept","application/json");
httpPost.setHeader(HTTP.TARGET_HOST,Constants.REGISTRATION_HOST + ":" + Constants.REGISTRATION_PORT);

//Set the content as enitity within the HttpPost object     
httpPost.setEntity(registrationRequest_json_entity);

HttpResponse response = httpClient.execute(httpPost, new BasicHttpContext());
HttpEntity entity = response.getEntity();
if (entity != null) {
    //work on the response
}
EntityUtils.consume(entity);

尝试：

---

这会将内容长度设置为0。

HttpClient会根据所附消息实体的属性和实际协议设置自动生成

内容长度

和

传输编码

头值

---

不要手动设置这些标题

您可以添加用于创建请求的代码吗？当然可以。。将使用我的代码更新帖子您如何确定未发送

内容长度

标题？

//Convert the registration request object to json
StringEntity registrationRequest_json_entity = new StringEntity(gsonHandle.toJson(registrationRequest));
registrationRequest_json_entity.setContentType("application/json");

//Creating the HttpPost object which contains the endpoint URI
HttpPost httpPost = new HttpPost(Constants.CLIENT_REGISTRATION_URL);
httpPost.setHeader(HTTP.CONTENT_TYPE,"application/json");
httpPost.setHeader("Accept","application/json");
httpPost.setHeader(HTTP.TARGET_HOST,Constants.REGISTRATION_HOST + ":" + Constants.REGISTRATION_PORT);

//Set the content as enitity within the HttpPost object     
httpPost.setEntity(registrationRequest_json_entity);

HttpResponse response = httpClient.execute(httpPost, new BasicHttpContext());
HttpEntity entity = response.getEntity();
if (entity != null) {
    //work on the response
}
EntityUtils.consume(entity);

httppost.setHeader(HTTP.CONTENT_LEN,"0");