Develop Reference

Does HttpURLConnection work for sdk22?

Does HttpURLConnection that works for android API 23 also work for android API22?
I'm trying to program for android version over 4.0.
I am unsure if the difference between sdk22 and sdk23 will cause a problem
// http client
URL url = new URL(url1);
HttpURLConnection httpClient = (HttpURLConnection) url.openConnection();
httpClient.setRequestMethod("POST");
httpClient.setUseCaches(false);
httpClient.setDoInput(true);
httpClient.setDoOutput(true);
httpClient.setRequestProperty("Connection", "Keep-Alive");
httpClient.addRequestProperty("Content-length", reqEntity.getContentLength() + "");
OutputStream os = httpClient.getOutputStream();
reqEntity.writeTo(httpClient.getOutputStream());
os.close();
httpClient.connect();
if (httpClient.getResponseCode() == HttpURLConnection.HTTP_OK) {
return readStream(httpClient.getInputStream());

Yes it will work without any issues, and the difference will not cause any problem
HttpUrlConnection is available in from API Level 1 , you can further get more insight from the docs.
Its a good practice to use HttpUrlConnection over deprecated Apache HttpClient classes,

HttpURLConnection getInputStream() returns empty for specific device

Im experiencing a strange behaviour when using HttpURLConnection getInputStream() on a different devices. On all devices except "Alcatel" im getting a valid input stream only for Alcatel devices im getting a different(empty) kind of input stream:
All devices except alcatel
Alcatel devices
Im making the exact same call and getting 200 for all the devices.
The code is pretty straightforward:
urlObj = new URL(url);
urlConnection = (HttpURLConnection)urlObj.openConnection();
urlConnection.setRequestMethod(method);
urlConnection.setDoInput(true);
urlConnection.setConnectTimeout(timeout);
urlConnection.setReadTimeout(timeout);
urlConnection.setDoOutput(true);
urlConnection.setFixedLengthStreamingMode(body.length);
urlConnection.setRequestProperty(HEADER_KEY_CONTENT_LENGTH, String.valueOf(body.length));
urlConnection.getOutputStream().write(body);
int responseCode = urlConnection.getResponseCode();
InputStream in = urlConnection.getInputStream();
Any suggestions?

Please check if you need to have proxy setting for alcatel. httpurlconnection may fail without proper proxy gateway.

setRequestProperty throwing java.lang.IllegalStateException: Cannot set request property after connection is made

I am getting java.lang.IllegalStateException:
java.lang.IllegalStateException: Cannot set request property after connection is made error when setRequestProperty method is called after
url.openConnection();
Here is what i am trying:
URL url = new URL("https://49.205.102.182:7070/obsplatform/api/v1/mediadevices/545b801ce37e69cc");
urlConnection = (HttpsURLConnection) url
.openConnection();
urlConnection.setRequestProperty("Content-Type","application/json");
any suggestions please? Thanks in advance.

This usually happens if you have in the debug watchers calls, such as conn.getResponseCode() or anything that queries the request result before the request was actually issued or completed.
This causes, that during debug, a request is performed by the watcher, before having properly set you request, and then it becomes invalid.

I only have this issue while in debugging mode,
Run without debugging (You can print logs) everything should work fine

The obvious thing is to think that you need to add properties before calling open on the URL. this however is not the case. i have seen many samples of settings being set AFTER url has been open (as counter intuitive as that is).
the problem in my case is that i had conn.getResponseCode() added in my watch list. removed that and all good.
... tricky.

please check below code
HttpURLConnection httpcon = (HttpURLConnection) ((new URL("a url").openConnection()));
httpcon.setDoOutput(true);
httpcon.setRequestProperty("Content-Type", "application/json");
httpcon.setRequestProperty("Accept", "application/json");
httpcon.setRequestMethod("POST");
httpcon.connect();

I was getting the same exception on setRequestProperty("Range","byte=" + downloadedSize + "-") .
After adding connection.setChunkedStreamingMode(0); the issue disappeared

I'm having the same issue.
I was observing this issue on Nexus 5. Code of my app constantly fails with the same exception (or its twin brother "cannot set request method ..")
What I've observed that it happens if i leave phone for a while. One it starts failing it fails all the time - but if i restart phone/emulator it's ok once again).
My suspicion is its either some bug in connection pooling on framework side, or somewhere in code resources are leaked.

i found the problem it's about ordering the code, if you are trying to add header and post parameters both, it's important to be careful about this
HttpURLConnection connection = (HttpURLConnection) urlConnection;
//// Add Request Headers
for (NameValuePair nvp :
request[0].getHeaderParams()) {
connection.setRequestProperty(nvp.getName(),nvp.getValue());
}
// done
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setRequestMethod("POST");
//// Add Post Parameters
OutputStream outputStream = urlConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream));
List<NameValuePair> params = new ArrayList<>(request[0].getPostParams());
bufferedWriter.write(getQuery(params));
// done
connection.setConnectTimeout(3000);
connection.setReadTimeout(3000);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.flush();
outputStream.close();
connection.connect();
in here, i have added header parameters then set setDoInput and setDoOutput then setRequestMethod and finally you can add POST parameters.
i don't know what is wrong with setRequestMethod but i think its preparing the connection by opening it or something and that's why it throws exception

not invoke setRequestProperty after write byte to OutputStream.
OutputStream os = connection.getOutputStream();
os.write("k=v".getBytes());
os.close();
you should invoke setRequestProperty above the code

To avoid the error:
java.lang.IllegalStateException: Cannot set request property after connection is made
We have to check the connection response before access the request header fields :
URL url = new URL("https://49.205.102.182:7070/obsplatform/api/v1/mediadevices/545b801ce37e69cc");
urlConnection = (HttpsURLConnection) url
.openConnection();
//Check connection
if(urlConnection.getResponseCode() == 200/*Successful*/) {
urlConnection.setRequestProperty("Content-Type","application/json");
...
...
}

missing parameter when sending request to server with HttpURLConnection

I need to post schoolname=xyz&schoolid=1234 to server. I wrote the following Android client code:
String data = "schoolname=xyz&schoolid=1234";
//The url is correct
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
conn.setRequestProperty("Accept-Encoding", "gzip");
conn.setDoInput(true);
conn.setDoOutput(true);
OutputStream os = new BufferedOutputStream(conn.getOutputStream());
os.write(data.toString().getBytes("UTF-8"));
//response complains that missing parameter 'schoolname'
int responseCode = conn.getResponseCode();
...
After I send my request with above code, server however constantly complains that schoolname parameter is missing. What do I miss or did wrong?

Have a look at [this example that explains How to use a HttpURLConnection to POST data
If you're planning on doing a lot of web communication, take a look at Square's Retrofit which will help you automate a lot of this work.

You can't use the format "key=value&key1=value1" for http post. That would work fine only for get. In this case you need something like this:
List<NameValuePair> nameValuePairs;
nameValuePairs.add(new BasicNameValuePair("schoolname", "xyz"));
nameValuePairs.add(new BasicNameValuePair("schoolid", "1234"));
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs, "UTF-8"));
httpPost.execute();

I figured out myself, the reason is that I forget to call flush() on output stream. After flush it, everything works fine.

Problems on POST REQUEST HttpURLConnection Android 4.0+

I'm having some trouble making a simple HTTP POST request on a website. It seems like the POST parameters is not being sent!
Scenario:
HTTP Response code 200 - Wrong User/Pass - Occurring on Android 4.0+
HTTP Response code 302 - User/Pass OK - Occurring on others SDK versions
The Web form thats works OK:
<form id="form_mn_login" enctype="application/x-www-form-urlencoded" action="http://dummyhost/r.php" class="estil" accept-charset="utf-8" method="post">
<input type="text" name="m_email" id="m_email" />
<input type="password" name="m_senha" id="m_senha" />
The code (inside doInBackground AsyncTask's method):
urlParameters = "m_email="
+ URLEncoder.encode(username, "UTF-8") + "&m_senha="
+ URLEncoder.encode(password, "UTF-8");
URL url;
HttpURLConnection connection = null;
// Create connection
url = new URL("http://dummyhost/r.php");
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Language", "en-US");
connection.setUseCaches(false);
connection.setDoInput(true);
connection.setDoOutput(true);
// Send request
DataOutputStream wr = new DataOutputStream(
connection.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();
publishProgress(30);
Log.w("responsecode", Integer.toString(connection.getResponseCode()));
This issue only shows up when I emulate it on Android 4.0+ AVD Devices. (Tried on 2.2,2.3.3, 3.0 and it works flawlessly)
What am I missing?
I'm aware maybe this is an server issue, but I really believe there must be an workaround for this. I've tried thousands of different ways of doing it but none seems to work as it should.
Thanks a lot,
RC