Develop Reference

Android to Django - always showing 401

I am trying to connect to my Django backend server from my app. While in local/dev with http connection the android app is getting connected to the server, it is rreturning HTT 401 error for all API calls via the app (except the login call). However, funny thing is using Postman, I'm being able to reach the prod server.
Following is one of the code snippets (android):
try{
URL targetUrl = new URL(targetURL);
httpConnection = (HttpURLConnection) targetUrl.openConnection();
httpConnection.setRequestMethod("GET");
httpConnection.setRequestProperty("Authorization", "jwt " + mToken);
httpConnection.setConnectTimeout(10000); //10secs
httpConnection.connect();
Log.i(TAG, "response code:" + httpConnection.getResponseCode());
if (httpConnection.getResponseCode() != 200){
Log.e(TAG, "Failed : HTTP error code : " + httpConnection.getResponseCode());
return Constants.Status.ERR_INVALID;
}
//Received Response
InputStream is = httpConnection.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
while((line = rd.readLine()) != null) {
response.append(line);
//response.append('\r');
}
rd.close();
Log.i(TAG, response.toString());
// Save the tenant details
return parseTenantInfo(response.toString());
}catch (MalformedURLException e) {
e.printStackTrace();
return Constants.Status.ERR_NETWORK;
} catch (SocketTimeoutException e) {
e.printStackTrace();
return Constants.Status.ERR_NETWORK;
}
catch (IOException e) {
e.printStackTrace();
return Constants.Status.ERR_UNKNOWN;
}finally {
if(httpConnection != null) {
httpConnection.disconnect();
}
}
Following is the target url:
private static final String targetURL = Constants.SERVER_ADDR + APIs.tenant_get;
Here, SERVER_ADDR is https://www.example.com/ and tenant_get is apitogettenantinfo/
I am always getting 401 error. Kindly help me out!!! Thanks.
The most irritating thing is Postman works, android login works. So it is seemingly no issue with server (else how would postman work?). And I can't understand what the android issue is.
EDIT:
Following is the screenshot of my postman. A few things are blacked out for security & privacy:
http://imageshack.com/a/img923/231/wUrOuS.png

401 indicates unauthorised request, make sure you are sending correct token.
Also remove httpConnection.connect();

Why am I getting 500 response code on passing wrong email or password to service in android?

I have been running into a very strange problem. I am trying to implement log in service in my app. When I pass right email and password service returns response as expected(means no error comes) but when I delibrately pass wrong email or password geInputStream() method throws FileNotFoundException. I don't know what is the reason behind this.Further more, before calling getInputStream() method i checked status code as well(this is the case when I am passing wrong email and password intentionally).The status code was 500. I checked for 500 and that was internal server error. My question is why is that so? I mean when intentionally passing wrong email or password why internal server occurred? One more thing I would like to mention that I have checked the same service on post man it is working fine as expected. If i pass wrong email or password postman returns the expected error. Below is the code I am using
private String invokeWebservice() {
String data = null;
HttpURLConnection conn = null;
BufferedReader in = null;
try {
String webservice = Constants.BASE_URL + serviceName;
LogUtility.debugLog("webservice just called "+ webservice);
URL url = new URL(webservice);
conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000);
conn.setConnectTimeout(15000);
conn.setUseCaches(false);
if (isPost) {
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("Accept", "application/json");
Writer writer = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(), "UTF-8"));
if (jsonObject != null)
writer.write(jsonObject.toString());
writer.close();
}
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuffer sb = new StringBuffer("");
String l = "";
String nl = System.getProperty("line.separator");
while ((l = in.readLine()) != null)
sb.append(l + nl);
in.close();
data = sb.toString();
return data;
} catch (Exception e) {
LogUtility.errorLog("exception while calling web service");
} finally {
try {
if (conn != null)
conn.disconnect();
if (in != null)
in.close();
} catch (Exception ex) {
// LogUtility.errorLogWithException(ex, ex.getMessage());
}
}
return data;
}
Any help?

After spending some time now I was able to solve my problem.Posting my answer for others. Passing wrong email and password to the service was right and server was consuming those parameters as well and because there was an error(because email and password) that is why it was returning 500 code. So, I checked for status code if it was 200 then I used getInputStream() method and else i called getErrorStream() method. By this way i got the stream that has property for error(this property contains error detail). Below is the code i used
if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
in = new BufferedReader(new InputStreamReader(conn.getErrorStream()));
} else {
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
}
Hope it helps other as well.

URLConnection - Cannot write request body after response has been read [duplicate]

I'm writing a program that connects to a servlet thanks to a HttpURLConnection but I stuck while checking the url
public void connect (String method) throws Exception {
server = (HttpURLConnection) url.openConnection ();
server.setDoInput (true);
server.setDoOutput (true);
server.setUseCaches (false);
server.setRequestMethod (method);
server.setRequestProperty ("Content-Type", "application / xml");
server.connect ();
/*if (server.getResponseCode () == 200)
{
System.out.println ("Connection OK at the url:" + url);
System.out.println ("------------------------------------------- ------- ");
}
else
System.out.println ("Connection failed");
}*/
I got the error :
java.net.ProtocolException: Cannot write output after reading input.
if i check the url with the code in comments but it work perfectly without it
unfortunately, I need to check the url so i think the problem comes from the getResponseCode method but i don t know how to resolve it
Thank you very much

The HTTP protocol is based on a request-response pattern: you send your request first and the server responds. Once the server responded, you can't send any more content, it wouldn't make sense. (How could the server give you a response code before it knows what is it you're trying to send?)
So when you call server.getResponseCode(), you effectively tell the server that your request has finished and it can process it. If you want to send more data, you have to start a new request.
Looking at your code you want to check whether the connection itself was successful, but there's no need for that: if the connection isn't successful, an Exception is thrown by server.connect(). But the outcome of a connection attempt isn't the same as the HTTP response code, which always comes after the server processed all your input.

I think the exception is not due toprinting url. There should some piece of code which is trying to write to set the request body after the response is read.
This exception will occur if you are trying to get HttpURLConnection.getOutputStream() after obtaining HttpURLConnection.getInputStream()
Here is the implentation of sun.net.www.protocol.http.HttpURLConnection.getOutputStream:
public synchronized OutputStream getOutputStream() throws IOException {
try {
if (!doOutput) {
throw new ProtocolException("cannot write to a URLConnection"
+ " if doOutput=false - call setDoOutput(true)");
}
if (method.equals("GET")) {
method = "POST"; // Backward compatibility
}
if (!"POST".equals(method) && !"PUT".equals(method) &&
"http".equals(url.getProtocol())) {
throw new ProtocolException("HTTP method " + method +
" doesn't support output");
}
// if there's already an input stream open, throw an exception
if (inputStream != null) {
throw new ProtocolException("Cannot write output after reading
input.");
}
if (!checkReuseConnection())
connect();
/* REMIND: This exists to fix the HttpsURLConnection subclass.
* Hotjava needs to run on JDK.FCS. Do proper fix in subclass
* for . and remove this.
*/
if (streaming() && strOutputStream == null) {
writeRequests();
}
ps = (PrintStream)http.getOutputStream();
if (streaming()) {
if (strOutputStream == null) {
if (fixedContentLength != -) {
strOutputStream =
new StreamingOutputStream (ps, fixedContentLength);
} else if (chunkLength != -) {
strOutputStream = new StreamingOutputStream(
new ChunkedOutputStream (ps, chunkLength), -);
}
}
return strOutputStream;
} else {
if (poster == null) {
poster = new PosterOutputStream();
}
return poster;
}
} catch (RuntimeException e) {
disconnectInternal();
throw e;
} catch (IOException e) {
disconnectInternal();
throw e;
}
}

I have this problem too, what surprises me is that the error is caused by my added code System.out.println(conn.getHeaderFields());
Below is my code:
HttpURLConnection conn=(HttpURLConnection)url.openConnection();
conn.setRequestMethod("POST");
configureConnection(conn);
//System.out.println(conn.getHeaderFields()); //if i comment this code,everything is ok, if not the 'Cannot write output after reading input' error happens
conn.connect();
OutputStream os = conn.getOutputStream();
os.write(paramsContent.getBytes());
os.flush();
os.close();

I had the same problem.
The solution for the problem is that you need to use the sequence
openConnection -> getOutputStream -> write -> getInputStream -> read
That means..:
public String sendReceive(String url, String toSend) {
URL url = new URL(url);
URLConnection conn = url.openConnection();
connection.setDoInput(true);
connection.setDoOutput(true);
connection.sets...
OutputStreamWriter out = new OutputStreamWriter(conn.getOutputStream());
out.write(toSend);
out.close();
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String receive = "";
do {
String line = in.readLine();
if (line == null)
break;
receive += line;
} while (true);
in.close();
return receive;
}
String results1 = sendReceive("site.com/update.php", params1);
String results2 = sendReceive("site.com/update.php", params2);
...

How to accept Self Signed Certificates on Android

After a couple of days of fruitless searching and trying various suggestions and examples im still struggling with this.
The situation is we are developing an Android app against a DEVELOPMENT system (ie not open to use outside IT). It has a self signed certificate. The live system will have a "proper" certificate so I dont really want to be disabling the certificate check just to develop it.
The error I am receiving is a 401 Authorization error. I have tried the request with the Authorization credentials through fiddler and the REST service is chugging away nicely.
The certificate is in the Trusted credentials store on the device under user.
Here is the code that makes the connection.
try {
StringBuilder pathName = new StringBuilder();
StringBuilder data = new StringBuilder();
pathName.append(getApiCall()+ path);
URL url = new URL(pathName.toString());
HttpsURLConnection urlConnection = (HttpsURLConnection) url.openConnection(Proxy.NO_PROXY);
urlConnection.setRequestProperty("Autorization", getCredentials());
urlConnection.setDoInput(true);
urlConnection.setRequestMethod("GET");
urlConnection.setRequestProperty("Content-Type", "application/json");
try
{
InputStream in = urlConnection.getInputStream();
BufferedReader r = new BufferedReader(new InputStreamReader(in));
while ( r.readLine() != null)
{
String dataLine = r.readLine();
data.append(dataLine);
}
}
catch (Exception ex2)
{
int freda = urlConnection.getResponseCode();
String fred = urlConnection.getResponseMessage();
data.append("ERROR");
}
finally
{
urlConnection.disconnect();
}
return data.toString();
}
catch (Exception e)
{
return "ERROR";
}
If anyone could point me in the right direction I would be extremely grateful.
Thanks
Steve

Sending special characters (ë ä ï) in POST body with DataOutputStream in Android

Im currently working on an Android app with heavy server side communication. Yesterday I got a bug report saying that the users aren't able to send (simple) special characters such as ëäï.
I searched but didn't find anything helpful
Possible duplicate ( without answer ):
https://stackoverflow.com/questions/12388974/android-httpurlconnection-post-special-charactes-to-rest-clint-in-android
My relevant code:
public void execute(String method) {
HttpsURLConnection urlConnection = null;
try {
URL url = new URL(this.url);
urlConnection = (HttpsURLConnection) url.openConnection();
urlConnection.setRequestMethod(method);
urlConnection.setReadTimeout(30 * 1000);
urlConnection.setDoInput(true);
if (secure)
urlConnection.setRequestProperty("Authorization", "Basic " + getCredentials());
if (body != null) {
urlConnection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
urlConnection.setFixedLengthStreamingMode(body.length());
urlConnection.setDoOutput(true);
DataOutputStream dos = new DataOutputStream(urlConnection.getOutputStream());
dos.writeBytes(body);
dos.flush();
dos.close();
}
responseCode = urlConnection.getResponseCode();
message = urlConnection.getResponseMessage();
InputStream in = null;
try {
in = new BufferedInputStream(urlConnection.getInputStream(), 2048);
} catch (Exception e) {
in = new BufferedInputStream(urlConnection.getErrorStream(), 2048);
}
if (in != null)
response = convertStreamToString(in);
} catch (UnknownHostException no_con) {
responseCode = 101;
}catch (ConnectException no_con_2){
responseCode = 101;
}catch(IOException io_ex){
if(io_ex.getMessage().contains("No authentication challenges found")){
responseCode = 401;
}else
responseCode = 101;
} catch (Exception e) {
e.printStackTrace();
} finally {
if (urlConnection != null)
urlConnection.disconnect();
}
}
body is a String ;-)
Hope we can solve this together
UPDATE:
Tried:
writeUTF()
need a server capable of understanding the modified UTF-8
byte[] buf = body.getBytes("UTF-8");
dos.write(buf, 0, buf.length);
strings work but no special chars
update: Got it working with StringEntity(* string, "UTF-8") then parse the result to a byte[] and write it with dos.write(byte[])!
--

Setting the encoding of the StringEntity did the trick for me:
StringEntity entity = new StringEntity(body, "UTF-8");
seen here: https://stackoverflow.com/a/5819465/570168

i am not totally sure buy try this utility for your case
URLEncoder.encode(string, "UTF-8")

I faced this problem in android while passing a json with special char (ñ).
In my WebApi method, [FromBody] param is giving null, it seems it can't parse the json.
I got it working by getting bytes as UTF-8 then writing it in DataOutputStream (Client-side fix).
byte[] b = jsonString.getBytes("UTF-8");
os.write(b, 0, b.length);