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Java executing curl command using HttpURLConnection returns 204 (HTTP_NO_CONTENT)

I am using Java 11. I have the the following curl command, when I execute on the command line:
curl --location --request GET 'http://xxx.xxx.co.za:8080/document/details/Select+docId+From+%27Workflow+Club%2FCustomer+Invoices%27+where+recursive+%3D+true+and+invoice_number+%3D%271221669023%27' --header 'Authorization: Basic xxx'
Returns the following:
{errorMessage: 'PaperTrail API only available in enterprise edition'}
However, when I try execute the same URL in a Java application using HttpURLConnection, it returns a blank response.
private static final String USER_AGENT = "Mozilla/5.0";
private static final String GET_URL = "http://xxx.xxx.co.za:8080/document/details/";
private static final String GET_URL_QRY = "Select docId From 'Workflow Club/Customer Invoices' where recursive = true and invoice_number =':1'";
private static final String GET_AUTH_ENC = "Basic xxx";
#Override
public String getDocId(Long invoiceNumber) {
String get_url_qry = StringUtils.replace(GET_URL_QRY, ":1", Long.toString(invoiceNumber));
get_url_qry = URLEncoder.encode(get_url_qry, StandardCharsets.UTF_8);
final String get_url = GET_URL+get_url_qry;
try {
URL url = new URL(get_url);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestProperty("Authorization", GET_AUTH_ENC);
con.setRequestMethod("GET");
con.setRequestProperty("User-Agent", USER_AGENT);
int responseCode = con.getResponseCode();
logger.info(get_url+" -> GET Response Code :: " + responseCode);
if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_NO_CONTENT) { // success
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
String resp = response.toString();
logger.info(responseCode+" Response: '"+resp+"'.");
} else {
logger.error("GET request did not work (responseCode: "+responseCode+").");
}
} catch (MalformedURLException e) {
logger.error("MalformedURLException creating URL '"+get_url+"'. "+e.getMessage());
} catch (IOException e) {
logger.error("IOException creating connection from URL '"+get_url+"'. "+e.getMessage());
}
return null;
}
Outputs the following with a blank response:
204 Response: ''.
Question
How do I get the Java application to also return the same as the command line call?
UPDATE
I have a different POST url, that I need to call too, and I can call it successfully. So there's something wrong with my GET call.
private static final String USER_AGENT = "Mozilla/5.0";
E.g. GET call that returns a 204, with no content.
private String getDocId(Long invoiceNumber) {
String get_url_qry = StringUtils.replace(GET_URL_QRY, ":1", Long.toString(invoiceNumber));
get_url_qry = URLEncoder.encode(get_url_qry, StandardCharsets.UTF_8);
final String get_url = GET_URL+get_url_qry;
try {
URL url = new URL(get_url);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestProperty("Authorization", GET_AUTH_ENC);
con.setRequestMethod("GET");
con.setRequestProperty("User-Agent", USER_AGENT);
con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
Map<String,String> data = handleResponse(con);
return data.get("docId");
} catch (MalformedURLException e) {
logger.error("MalformedURLException creating URL '"+get_url+"'. "+e.getMessage());
} catch (IOException e) {
logger.error("IOException creating connection from URL '"+get_url+"'. "+e.getMessage());
}
return null;
}
The POST call, that returns a 200, and the expected content.
private String getDocLink(String docId) {
if (StringUtils.isNotBlank(docId)) {
try {
URL url = new URL(POST_URL);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestProperty("Authorization", GET_AUTH_ENC);
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", USER_AGENT);
con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
byte[] postDataBytes = getPostData(docId);
con.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
con.setDoOutput(true);
con.getOutputStream().write(postDataBytes);
Map<String,String> data = handleResponse(con);
return data.get("url");
} catch (IOException e) {
logger.error("IOException creating connection from URL '"+POST_URL+"'. "+e.getMessage());
}
} else {
logger.error("No docId provided when trying to get a document link.");
}
return null;
}
So seeing the that POST call works, I think I must be doing something wrong with the GET call.

Did you try, setting the same user agent in your Java Code, cURL would use? something like curl/7.37.0?
As far as I can tell, that should be all, what differs. Aside cURL following redirects. But as there is no redirect, I guess it might be the User Agent making a difference.
There are a lot of server applications, behaving differently, when they are called by a browser (Like you make it think by setting the User-Agent to Mozilla/5.0), instead of some other application, like cURL.

From what you describe, the original call produces an error.
Assuming that you are also getting some form of error in the java code of your GET, you will catch the exception and simply log it. Then you will return null instead of a string, which will cause your response to have no content, i.e. 204.

PHP is not receieving data from a POST request with AsyncTask

I am trying to receieve a simple string from my PHP script by using a POST request in Android Studio.
If I write for example echo "Hello"; I can receive this message in my app, but it seems like as soon as I send a POST request my webserver doesen't really get the message.
Here is how I do the POST request in my AsyncTask:
class HTTPReqTask extends AsyncTask<String, Void, String>
{
Activity activity;
OnDataSendToActivity dataSendToActivity;
Context context;
public HTTPReqTask(Context context)
{
this.context = context;
dataSendToActivity = (OnDataSendToActivity) ((Activity) context);
}
#Override
public String doInBackground(String... params)
{
HttpURLConnection urlConnection = null;
String param1 = params[0];
String line = "";
String result = "";
try
{
JsonObject postData = new JsonObject();
postData.addProperty("a", "1");
URL url = new URL(param1);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestProperty("Content-Type", "application/json");
urlConnection.setRequestMethod("POST");
urlConnection.setDoOutput(true);
urlConnection.setDoInput(true);
urlConnection.setChunkedStreamingMode(0);
OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out,"UTF-8"));
writer.write(postData.toString());
int code = urlConnection.getResponseCode();
if (code != HttpURLConnection.HTTP_OK) {
throw new IOException("Invalid response from server: " + code);
}
BufferedReader rd = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
while ((line = rd.readLine()) != null)
{
result += line;
}
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
if (urlConnection != null)
{
urlConnection.disconnect();
}
}
return result;
}
#Override
protected void onPostExecute(String s)
{
try
{
if(dataSendToActivity != null)
{
Log.i("Data", s);
dataSendToActivity.sendData(s);
}
}
catch(Exception e)
{
// Nichts
}
}
}
As you can see I am using this:
JsonObject postData = new JsonObject();
postData.addProperty("a", "1");
to generate my POST request.
The postData string is: {"a":"1"}
This is my PHP script:
$post = file_get_contents("php://input");
$data = json_decode($post, true);
print_r($data);
UPDATE 1
I added now writer.flush(); (Thanks to Andy)
Now I'm getting this exception after sendung the request:
java.io.IOException: Invalid response from server: 500
So something with my PHP script is wrong.
Any suggestions?

I found now the problem.
The problem was not serversided as I expected it.
I was logging in my code some informations for the POST request and there I found this:
Log.i("LOG", urlConnection.getOutputStream().toString());
gave me this:
buffer(com.android.okhttp.internal.http.HttpConnection$ChunkedSink#843d1c8).outputStream()
So I commented this line out:
urlConnection.setChunkedStreamingMode(0);
and it works fine. I get all my data I need.
I also updated my PHP script to this:
$post = file_get_contents("php://input");
if (!empty($post))
{
$data = json_decode($post, true);
$a = $data['a'];
}
Thanks for all the help!

How to send a Java POST request [duplicate]

This question already has answers here:
Sending HTTP POST Request In Java
(12 answers)
Closed 4 years ago.
I am completely lost on how to send a POST request in Java. I understand how to do in Python with the request module, but no luck with Java. So, I was wondering if anyone could give me a clear example of how this is done via logging into a webpage such as instagram.com. I appreciate all responses. Thanks in advance.

if you do not want to use extra library，you can try HttpURLConnection:
public static String doPost(String url, String postData) {
PrintWriter out = null;
BufferedReader in = null;
String result = "";
try {
URL realUrl = new URL(url);
// build connection
URLConnection conn = realUrl.openConnection();
// set request properties
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
// enable output and input
conn.setDoOutput(true);
conn.setDoInput(true);
out = new PrintWriter(conn.getOutputStream());
// send POST DATA
out.print(postData);
out.flush();
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result += "/n" + line;
}
} catch (Exception e) {
e.printStackTrace();
}
finally {
try {
if (out != null) {
out.close();
}
if (in != null) {
in.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
return result;
}

You can use Spring Web RestTemplate:
new RestTemplate().postForObject(url, requestObject, responseType);

you can use OkHttp
https://github.com/square/okhttp
public static final MediaType JSON
= MediaType.parse("application/json; charset=utf-8");
OkHttpClient client = new OkHttpClient();
String post(String url, String json) throws IOException {
RequestBody body = RequestBody.create(JSON, json);
Request request = new Request.Builder()
.url(url)
.post(body)
.build();
Response response = client.newCall(request).execute();
return response.body().string();
}

Java: read data sent by HTTP POST (Android AVD)

I use a simple WebServer from http://www.java2s.com/Code/Java/Network-Protocol/AverysimpleWebserverWhenitreceivesaHTTPrequestitsendstherequestbackasthereply.htm
and Android code from Sending json object via http post method in android
In my main Activity:
AsyncT asyncT = new AsyncT();
asyncT.execute();
Class:
class AsyncT extends AsyncTask<Void,Void,Void>{
#Override
protected Void doInBackground(Void... params) {
try {
URL url = new URL(""); //Enter URL here
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setDoOutput(true);
httpURLConnection.setRequestMethod("POST"); // here you are telling that it is a POST request, which can be changed into "PUT", "GET", "DELETE" etc.
httpURLConnection.setRequestProperty("Content-Type", "application/json"); // here you are setting the `Content-Type` for the data you are sending which is `application/json`
httpURLConnection.connect();
JSONObject jsonObject = new JSONObject();
jsonObject.put("para_1", "arg_1");
DataOutputStream wr = new DataOutputStream(httpURLConnection.getOutputStream());
wr.writeBytes(jsonObject.toString());
wr.flush();
wr.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}
The connection is established without any errors ("HostConnection::get() New Host Connection established"). However, I am not able to get in my Java server any information from the request. When I read from input stream
BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
System.out.println(in);
I get java.io.BufferedReader#4d7hge12
And this outputs nothing:
String line;
while ((line = in.readLine()) != null) {
if (line.length() == 0)
break;
System.out.println(line);
}

Don't re-invent the wheel and use a library for this.
For example okhttp:
public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");
OkHttpClient client = new OkHttpClient();
String post(String url, String json) throws IOException {
RequestBody body = RequestBody.create(JSON, json);
Request request = new Request.Builder()
.url(url)
.post(body)
.build();
Response response = client.newCall(request).execute();
return response.body().string();
}
If you want to call a REST-API you can use retrofit (which is build ontop of okhttp)

Assuming you're doing this as a learning exercise, so using another library isn't what you're looking for, I would suggest a couple of things:
(1) install Wireshark and see what the actual response coming back the server is, does it look sensible?
(2) break that line of code out into separate lines, is the InputStream / InputStreamReader null?

Data of json request with strange characters in volley request

I am making a Json request and I get the data and place it in a list view but some of the strings i get have accents or 'ç' and it doesn't appear correctly.
For example, the string is 'Bragança' and i receive 'Bragança' or 'à' and get 'Ã'. If i do the request in the browser, all works properly.
My request.
public void makeJsonArrayRequest() {
RequestQueue queue = AppController.getInstance().getRequestQueue();
queue.start();
JsonArrayRequest Req = new JsonArrayRequest(urlJsonObjUtilizadas,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
Log.d(TAG, response.toString());
// Parsing json
for (int i = 0; i < response.length(); i++) {
try {
JSONObject ementaObj = response.getJSONObject(i);
Ementa ementa = new Ementa();
ementa.setCantina(ementaObj.getString("cantina"));
ementa.setDescricao(ementaObj.getString("descricao"));
ementa.setEmenta(ementaObj.getString("ementa"));
ementa.setPreco(ementaObj.getInt("preco"));
ementaItems.add(ementa);
} catch (JSONException e) {
e.printStackTrace();
}
}
// notifying list adapter about data changes
adapter.notifyDataSetChanged();
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
}
}) {
//**
// Passing some request headers
//*
#Override
public Map<String, String> getHeaders() {
HashMap<String, String> headers = new HashMap<String, String>();
headers.put("Content-Type", "application/json; charset=UTF-8");
return headers;
}
};
// Add the request to the RequestQueue.
AppController.getInstance().addToRequestQueue(Req);
}

I think this is because of the wrong content type encoding header. You are supposed to use UTF-8 as encoding. Maybe this is working in the browsers because the headers are not case-sensitive (unlike Android).
Take a look here for a solution. Essentially they are manually overriding the charset.

please try to use this code for sending and receiving JSON with utf-8 encoding:
try {
URL url = new URL("your url");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter writer = new OutputStreamWriter(
conn.getOutputStream(), "UTF-8");
String request = "your json";
writer.write(request);
writer.flush();
System.out.println("Code:" + conn.getResponseCode());
System.out.println("mess:" + conn.getResponseMessage());
String response = "";
BufferedReader reader = new BufferedReader(new InputStreamReader(
conn.getInputStream(), "UTF-8"));
String line;
while ((line = reader.readLine()) != null) {
response += line;
}
System.out.println(new String(response.getBytes(), "UTF8"));
writer.close();
reader.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

You should add the request header charset to UTF-8. For example if your request will be as json, you should add this header to the request:
"Content-type": "Aplicación/json; utf-8"
I use Volley too and this way works for me.
Regards.

Check this sample, this way i am using, look the header section
public class Estratek_JSONString extends JsonRequest<String>{
Activity Act;
Priority priority;
public Estratek_JSONString(int m, String url, JSONObject params,
Listener<String> listener, ErrorListener errorListener,Activity act, Priority p) {
super(m,url,params.toString(),listener,errorListener);
this.Act=act;
this.priority=p;
}
public Estratek_JSONString(int m, String url,
Listener<String> listener, ErrorListener errorListener,Activity act, Priority p) {
// super constructor
//super(m,url,params.toString(),listener,errorListener);
super(m,url,null,listener,errorListener);
this.Act=act;
this.priority=p;
}
#Override
public Map<String, String> getHeaders() {
HashMap<String, String> headers = new HashMap<String, String>();
headers.put("Content-Type", "application/json; charset=utf-8");
headers.put("Authorization", "Bearer "+Tools.Get_string(Act.getApplicationContext(),Global_vars.Access_token));
return headers;
}
//it make posible send parameters into the body.
#Override
public Priority getPriority(){
return priority;
}
#Override
protected Response<String> parseNetworkResponse(NetworkResponse response) {
try {
String jsonString =
new String(response.data, HttpHeaderParser.parseCharset(response.headers));
return Response.success(new String(jsonString),
HttpHeaderParser.parseCacheHeaders(response));
} catch (UnsupportedEncodingException e) {
return Response.error(new ParseError(e));
}
}
}