java 我应该为 POST HTTP 请求的 Content-Length 使用什么值？
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What value should I use for Content-Length of an POST HTTP request?
提问by Anton Kizema
I am trying to send HTTP request. Currently I am stuck on adding Content-Length property: I have
我正在尝试发送 HTTP 请求。目前我坚持添加 Content-Length 属性：我有
httpPost.addHeader("Accept", "application/json");
httpPost.addHeader("Content-Type", "application/json;charset=utf-8");
httpPost.addHeader("Content-Length", ""+json.length() );
If i comment last line (content-length) server returns me error that I miss smth, I last line stays uncommented - then I catch an exception when trying to do
如果我评论最后一行（内容长度）服务器返回我错过 smth 的错误，我最后一行保持未注释 - 然后我在尝试执行时捕获异常
HttpResponse httpResponse = httpclient.execute(httpPost);
Please, tell me what am I doing wrong with setting headers.
请告诉我我在设置标题时做错了什么。
PS I am sending easy JSON object
PS我正在发送简单的JSON对象
JSONObject jsonObject = new JSONObject();
jsonObject.accumulate("phone", phone);
My full code snippet of post metod:
我的帖子方法的完整代码片段：
public static JSONObject POST(String url, String phone){
InputStream inputStream = null;
String result = "";
try {
// 1. create HttpClient
HttpClient httpclient = new DefaultHttpClient();
// 2. make POST request to the given URL
HttpPost httpPost = new HttpPost(url);
String json = "";
// 3. build jsonObject
Log.d("ANT", "JSONObject jsonObject = new JSONObject(); PHONE:"+phone);
JSONObject jsonObject = new JSONObject();
jsonObject.accumulate("phone", phone);
// 4. convert JSONObject to JSON to String
json = jsonObject.toString();
// 5. set json to StringEntity
StringEntity se = new StringEntity(json);
// 6. set httpPost Entity
httpPost.setEntity(se);
Log.d("ANT", "json"+json.length());
// 7. Set some headers to inform server about the type of the content
httpPost.addHeader("Accept", "application/json");
httpPost.addHeader("Content-Type", "application/json;");
// httpPost.addHeader("Content-Length", ""+json.length() );
// 8. Execute POST request to the given URL
Log.d("ANT", "httpPost:"+getStringFromInputStream(httpPost.getEntity().getContent()));
for (Header s : httpPost.getAllHeaders())
Log.i("ANT", "header::"+s.getName() + ":"+s.getValue());
HttpResponse httpResponse = httpclient.execute(httpPost);
// 9. receive response as inputStream
inputStream = httpResponse.getEntity().getContent();
Log.d("ANT", "httpResponse.getEntity().getContent();");
// 10. convert inputstream to string
if (inputStream != null) {
result = getStringFromInputStream(inputStream);
Log.d("ANT", "getStringFromInputStream : "+result);
JSONObject obj = new JSONObject(result);
Log.d("ANT", "JSONObject");
return obj;
}
else
result = "Did not work!";
} catch (ClientProtocolException e) {
Log.d("ANT", "ClientProtocolException : "+ e.getLocalizedMessage());
} catch (IOException e) {
Log.d("ANT", "IOException:"+ e.getLocalizedMessage());
} catch (Exception e) {
Log.d("ANT", "Exception:"+ e.getLocalizedMessage());
}
// 11. return result
return null;
}
回答by fishi0x01
Can you elaborate on what the server error code is and a stack trace when the exception occurs?
您能否详细说明服务器错误代码是什么以及发生异常时的堆栈跟踪？
Edit:
编辑：
I tried some part of your code. I did not set the Content-Length (since this should be done automatically):
我尝试了您代码的一部分。我没有设置 Content-Length （因为这应该自动完成）：
public class App
{
public static void main( String[] args )
{
post("http://www.baidu.com","+8912345");
}
public static JSONObject post(String url, String phone){
InputStream inputStream = null;
String result = "";
try {
// 1. create HttpClient
HttpClient httpclient = new DefaultHttpClient();
// 2. make POST request to the given URL
HttpPost httpPost = new HttpPost(url);
String json = "";
// 3. build jsonObject
JSONObject jsonObject = new JSONObject();
jsonObject.accumulate("phone", phone);
// 4. convert JSONObject to JSON to String
json = jsonObject.toString();
// 5. set json to StringEntity
StringEntity se = new StringEntity(json);
// 6. set httpPost Entity
httpPost.setEntity(se);
// 7. Set some headers to inform server about the type of the content
httpPost.addHeader("Accept", "application/json");
httpPost.addHeader("Content-Type", "application/json;");
// 8. Execute
HttpResponse httpResponse = httpclient.execute(httpPost);
// 9. receive response as inputStream
inputStream = httpResponse.getEntity().getContent();
} catch (ClientProtocolException e) {
System.out.println("ClientProtocolException : "+e.getLocalizedMessage());
} catch (IOException e) {
System.out.println("IOException:"+ e.getLocalizedMessage());
} catch (Exception e) {
System.out.println("Exception:"+ e.getLocalizedMessage());
}
return null;
}
}
I used wireshark and could verify that the following request is going to baidu:
我使用了wireshark，可以验证以下请求是否会发送到百度：
POST / HTTP/1.1
Accept: application/json
Content-Type: application/json;
Content-Length: 20
Host: www.baidu.com
Connection: Keep-Alive
User-Agent: Apache-HttpClient/4.3.6 (java 1.5){"phone":"+8912345"}
POST / HTTP/1.1
接受：application/json
内容类型：application/json；
内容长度：20
主机：www.baidu.com
连接：Keep-Alive
User-Agent：Apache-HttpClient/4.3.6 (java 1.5){“电话”：“+8912345”}
This shows that the request is sent properly, which means the client side seems to be fine. That's why I would suggest to check the server side for errors. As I already mentioned I think you should use tcpdump or wireshark to check the traffic between client and server. This might give you a better understanding of what is going wrong.
这表明请求发送正确，这意味着客户端似乎没问题。这就是为什么我建议检查服务器端是否有错误。正如我已经提到的，我认为您应该使用 tcpdump 或 wireshark 来检查客户端和服务器之间的流量。这可能会让您更好地了解发生了什么问题。
