Develop Reference

Why is the example from developer.android not working

I'm about to code an Android app (using A.Studio 3.5.1) that should connect to a back-end using https. I'm quite new to the techniques so I looked at https://developer.android.com/training/articles/security-ssl.html#HttpsExample
I has four lines of code:
URL url = new URL("https://wikipedia.org");
URLConnection urlConnection = url.openConnection();
InputStream in = urlConnection.getInputStream();
copyInputStreamToOutputStream(in, System.out);
When I try it I get a red text;
new URL gives MalformedURLException
url.openConnection() gives IOException,
urlConnection.getInputStream() also
copyInputStreamToOutputStream is not found.
I have read about copyInputStreamToOutputStream, that it can be solved
copyInputStreamToOutputStream(in, System.out)
and
Easy way to write contents of a Java InputStream to an OutputStream
I tried the first way, using apache commons, with no success.
I'm mostly curious about the exceptions.
I will try another walk-through on
https://codelabs.developers.google.com/codelabs/android-network-security-config/
But it would be nice to learn about this...

I have faced similar situations many times. This occur because the webpage you are trying to reach doesn't return anything as a response after connection is established. So the parsing returns IOException as there is nothing to read in the response of URL after connection.
newURL is returning MalformedURLException because your url contains -- " -- which should be escaped as these are special characters.
Hope this helps.

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,

Decode bitmap from stream without Apache HTTP Client

Until recently, I decoded images from a web resource using the Apache HTTP Client using this code:
HttpGet httpRequest = new HttpGet(params[0].toURI());
HttpClient httpClient = new DefaultHttpClient();
HttpResponse response = httpClient.execute(httpRequest);
HttpEntity entity = response.getEntity();
BufferedHttpEntity bufferedEntity = new BufferedHttpEntity(entity);
return BitmapFactory.decodeStream(bufferedEntity.getContent());
This all worked perfectly fine.
Now with Android 6, Apache HTTP Client has been deprecated. Not to worry, I thought, just use java.net.HttpUrlConnection instead as recommended here:
http://developer.android.com/about/versions/marshmallow/android-6.0-changes.html#behavior-apache-http-client
The code I tried and that I found in other questions here is:
HttpURLConnection connection = (HttpURLConnection) params[0].openConnection();
// connection.setRequestProperty("User-Agent", "");
connection.setRequestMethod("GET");
// connection.setDoInput(true);
connection.connect();
InputStream inputStream = connection.getInputStream();
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
inputStream.close();
return bitmap;
This doesn't work. bitmap will always be null for the same image resource that works with the old code.
Does anyone have any insight into this? Here are other questions I tried and why they didn't work:
Android: bitmapfactory.decodestream returns null (Answers use deprecated methods/classes)
Bitmap.decodeStream returns null on specific existing (And working) images (Same as above)

The problem was caused by a simple HTTP/HTTPS issue. The image resource was requested from a http:// address. The server is set up to issue a 307 (temporary redirect) to the matching https:// address.
Although the default of HttpURLConnection is to follow redirects, the code given in the question didn't work. FYI Picasso didn't load the image either.
Requesting the image via its https:// address solved the problem.

Use Volley or Picasso. That's the recommended approach.

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");
...
...
}

Android HttpPut Has No Body, Despite Setting the Entity

I'm trying to PUT some XML to a server, but the gist of it is that no matter what I do, HttpPut simply won't put anything in the Http body. The server always comes back saying that the body is missing, and looking at it through Wireshark, nothing is there! Here's the code I'm using to set up and run the request:
HttpPut putRequest = new HttpPut(urlString]);
StringEntity stringEntity = new StringEntity(xmlString, HTTP.ISO_8859_1);
stringEntity.setContentType("text/xml");
putRequest.setEntity(stringEntity);
putRequest.addHeader("Host", formatUrlForHostHeader(broadsoftUrl));
putRequest.addHeader("Authorization", authorizationString);
putRequest.addHeader("Content-Type", "text/xml");
putRequest.addHeader("Accept", "text/xml");
response = httpClient.execute(putRequest);
I'm not sure what else to include here. I tried it on 4.2 and 4.0.3. This code is running in the doInBackground of an AsyncTask. The response code I get is a 409 Conflict, and the body is the server's application-specific message, telling me the body is missing. I confirmed that it's missing with Wireshark.
EDIT:
An interesting note is that I ran the same code standalone on my desktop, and it worked. So, is there something up with the Android versions of HttpClient, or the system? I tried a few different API levels, too, just to check.
Any thoughts?
Thanks!

Alright, so the solution was to just give up on HttpPut and all that, and use HttpURLConnection. Here's how we ended up doing it:
URL url = new URL(theUrl);
HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
httpCon.setRequestProperty("Host", formatUrlForHostHeader(broadsoftUrl));
httpCon.setRequestProperty("Authorization", authorizationString);
httpCon.setRequestProperty("Content-Type", "text/xml; charset=ISO_8859_1");
httpCon.setRequestProperty("Accept", "text/xml");
httpCon.setDoInput(true);
httpCon.setDoOutput(true);
httpCon.setRequestMethod("PUT");
OutputStreamWriter out = new OutputStreamWriter(httpCon.getOutputStream(), "ISO_8859_1");
out.write(xmlData);
out.close();
if(httpCon.getErrorStream() == null) {
return "";
} else {
return "ERROR";
}
We didn't need to get the response from our PUT request, but you check if it failed by seeing if the error stream exists. If you wanted to get the response, you would do something like this:
StringWriter writer = new StringWriter();
IOUtils.copy(httpCon.getInputStream(), writer, encoding);
String responseString = writer.toString();
Of course, you would have to include Apache's IOTools in your app.

409 Conflict is usually an Edit Conflict error, usually associated with wikis, but it could be any type of conflict with the request.
http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
What type of data are you trying to post and is it possible that the host has existing data that cannot be changed?