Develop Reference

JsonWriter POST not working in Android to WCF web service

I would like to know anyone has a sample code on how to use JsonWriter to post JSON data to WCF web service from Android?
I tested my WCF with Fiddler 4 (Composer with POST json data) and it gave me the correct return.
However, when I tested with my Android application which use JsonWriter, I didn't see any action on Fiddler (I set up Fiddler to check on my Android Emulator network traffic, by the way, I am testing on Android Emulator.).
With the same Android application, I can call GET with JsonReader to my WCF and get the correct reply.
Its just calling POST with JsonWriter got no response code or no action in Fiddler.
For JsonWriter (and Reader), I refer to Android developer >> JsonWriter
Here are my test results (Get and Post) with Emulator GET and POST.
Here are my test results with Fiddler direct POST.
First it gave me Result 307 then follow by 200.
And here is how I use JsonWriter to post (this block was from AsyncTask).
try
{
Log.d("TEST_JSON", "URL: " + params[0]);
URL url = new URL(params[0]);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Accept","application/json");
conn.setRequestProperty("Content-Type","application/json");
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setAllowUserInteraction(false);
// conn.connect();
OutputStream out = conn.getOutputStream();
JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8"));
try
{
writer.setIndent(" ");
if(params[1].trim() == "ARRAY")
{
// Write array to WCF.
}
else if(params[1].trim() == "OBJ")
{
// Write object to WCF. <<== I am testing with one object.
writer.beginObject();
writer.name("ShipNo").value("SI10101");
writer.name("DoNo").value("DO230401");
writer.name("PartNo").value("102931-1201");
writer.name("Qty").value(1);
writer.name("ShipIn").value(1);
writer.endObject();
}
}
finally
{
writer.close();
out.close();
}
// If I enable below blocks, I will see 307 response code in Fiddler.
/*
conn.connect();
int responseCode = conn.getResponseCode();
Log.d("TEST_JSON", "Code: " + String.valueOf(responseCode));
*/
Log.d("TEST_JSON", "Finish sending JSON.");
conn.disconnect();
}
catch (IOException e)
{
Log.e("TEST_JSON",e.getMessage()); // <<-- No error from this try catch block.
}
I tried and still cannot figure out why JsonWriter didn't trigger to my WCF (I attached my WCF to my localhost service, only Fiddler direct POST will hit the break point in my WCF project while Android App didn't reach to it). I follow the exact example from Android Developer site though. I google and didn't find any site on using JsonWriter with OutputStreamWriter (I saw some post using StringWriter).
May I know where did my code wrong ?

Based on this StackOverFlow post WCF has a 'Thing' about URI, I managed to solve this issue.
All I need is to make sure my POST web service has URI Template ends with "Slash".
Example: http://10.72.137.98/myWebSvc/posvctFun/
Instead of http://10.72.137.98/myWebSvc/postFun

Android HttpURLConnection throwing EOFException

Here's the question in simplest way.
I create a HTTPS connection to my server through proxy using HttpUrlConnection Object.
My proxy closes the connection but my code still tries to reuse the same connection. And so I get EOFException.
How do I handle such cases?

I'd recommend disabling the http.keepalive system property. The performance section of the documentation indicates that socket connections will be reused when possible. It sounds like it is trying to reuse the connection, but the proxy has already closed it. On this post, Darrell also indicates that changing the system property solved his problem.
System.setProperty("http.keepAlive", "false");

Turns out they've fixed this issue in Android on Jan 8th [1]. The fix basically marks the old connection as recycled and internally retries the request.
To fix this for now, I would suggest retrying requests if an EOFException is encountered with a retry limit to prevent stackoverlows.
https://android.googlesource.com/platform/libcore/+/19aa40c81c48ff98ccc7272f2a3c41479b806376

I had this problem with normal HTTP connections as well. The first request went OK, the second failed with an EOFException.
Eventuelly I fixed it by removing...
urlConnection.setChunkedStreamingMode(0);
...from the HttpUrlConnection.
I could be that the webserver I'm calling can't handle chuncked data well. Don't know.

If you don't want to reuse the connection then release it.
finally {
urlConnection.disconnect();
}

You can use this method to pick data from server then you convert the inputs trim to string then you can parse for further use.`
public static InputStream getUrlData(final String url)
throws URISyntaxException, ClientProtocolException, IOException {
final DefaultHttpClient client = new DefaultHttpClient();
final HttpGet method = new HttpGet(new URI(url));
final HttpResponse res = client.execute(method);
return res.getEntity().getContent();
}

Maybe httpClient "has more bugs" and is deprecated, but this problem with JellyBean is a showstopper. I am using Ksoap2 so I tried all the suggested answers that I could.
System.setProperty("http.keepAlive", "false");
httpTransportSE.getServiceConnection().setRequestProperty("Connection", "close");
httpTransportSE.getServiceConnection().disconnect();
Nothing worked - my solution was to rollback the version of Ksoap2 I'm using from 3.1.1 to 2.6.5. Using 2.6.5 the problem is substantially reduced. Still testing but maybe even solved.

I found that retrying the connection fixes the issue as seen here: https://stackoverflow.com/a/20302767/2520390
Make sure you close off the connection before your recursive call.
Also, I added the following to the connection to close the connection, though I'm not sure if it helps:
if (retries > 0) {
connection.setRequestProperty("Connection", "close");
}

You shouldn't be attempting to reuse the same HttpURLConnection instance. The docs in the very bottom line of the "Class Overview" say
Each instance of HttpURLConnection may be used for one
request/response pair.
Keep-Alive connections work at a different level, see the disconnect docs:
http://developer.android.com/reference/java/net/HttpURLConnection.html#disconnect()
Unlike other Java implementations, this will not necessarily close
socket connections that can be reused. You can disable all connection
reuse by setting the http.keepAlive system property to false before
issuing any HTTP requests.
So you should always use a fresh HttpURLConnection and let the socket pool handle re-use.
There were apparently bugs with keep-alive connections pre-Froyo (2.2) so it is recommended to disable keep-alive on those old devices.
In my case the EOFException was caused by my server not sending a full response, see the details here: https://stackoverflow.com/a/27845172/2335025

You shouldn't be attempting to reuse the same HttpURLConnection instance. The docs in the very bottom line of the "Class Overview" say
Each instance of HttpURLConnection may be used for one
request/response pair.
Keep-Alive connections work at a different level, see the disconnect docs:
http://developer.android.com/reference/java/net/HttpURLConnection.html#disconnect()
Unlike other Java implementations, this will not necessarily close
socket connections that can be reused. You can disable all connection
reuse by setting the http.keepAlive system property to false before
issuing any HTTP requests.
So you should always use a fresh HttpURLConnection and let the socket pool handle re-use. There are perhaps issues if it tries to reuse a socket that has been closed by the server, which the answers to this question deal with: Android HttpUrlConnection EOFException
There were apparently bugs with keep-alive connections pre-Froyo (2.2) so it is recommended to disable keep-alive on those old devices.
In my case the EOFException was caused by my server not sending a full response, see the details here: https://stackoverflow.com/a/27845939/2335025

if (Build.VERSION.SDK != null
&& Build.VERSION.SDK_INT > 13) {
con.setRequestProperty("Connection", "close");
}

Try this code:`
Httppost method:
HttpParams httpParams = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParams, TIMEOUT_MILLISEC);
HttpConnectionParams.setSoTimeout(httpParams, TIMEOUT_MILLISEC);
HttpClient client = new DefaultHttpClient(httpParams);
HttpPost request = new HttpPost("put_url");
request.setHeader("Content-Type", "application/xml");
String file = resourceXml();
StringEntity se = null;
try {
se = new StringEntity(file);
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
}
se.setContentEncoding("UTF-8");
se.setContentType("application/xml");
request.setEntity(se);
HttpResponse response = null;
try {
response = client.execute(request);
} catch (ClientProtocolException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
HttpEntity entity = response.getEntity();
InputStream is = null;
try {
is = entity.getContent();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
String _response = convertStreamToString(is);
Log.i(TAG, "Response:" + _response);
// Check if server response is valid code
int res_code = response.getStatusLine().getStatusCode();
Log.i(TAG, "status_code" + res_code);
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
`

to convert stream to string:`
private static String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is),
8192);
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append((line + "\n"));
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}`

Why connection is not establishing on first time?

I want to send my id & password to server and get the response from server. Here is my code. It is not working for the first time. But iam getting the response from server if i execute my application on second time. It is throwing "Post method failed: -1 null" on first time. Where iam wrong?? Why if() block is executing on first time?? could you please tell me.
HttpsURLConnection con = null;
String httpsURL = "https://www.abc.com/login";
String query = "id=xyz&password=pqr";
URL url = new URL(httpsURL);
con = (HttpsURLConnection) url.openConnection();
con.setRequestMethod("POST");
con.setRequestProperty("Content-length", String.valueOf(query.length()));
con.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
con.setRequestProperty("User-Agent","Mozilla/4.0(compatible; MSIE 5.0; Windows 98; DigExt)");
con.setDoInput(true);
con.setDoOutput(true);
DataOutputStream output = new DataOutputStream(con.getOutputStream());
output.writeBytes(query);
output.close();
int respCode = con.getResponseCode();
if (respCode != HttpsURLConnection.HTTP_OK)
{
throw new Exception("POST method failed: " + con.getResponseCode()+ "\t" + con.getResponseMessage()); }
else {
//read the content from server
}

1/ It is recommanded to use apache HttpClient rather than URLConnection (see http://developer.android.com/reference/org/apache/http/impl/client/DefaultHttpClient.html)
2/ for login and password, why not use Http Authentication ? both basic and digest are supported by android.
3/ as for you problem, you don't close the underlying outputStream.
you should do:
OutputStream os = con.getOutputStream();
DataOutputStream output = new DataOutputStream(os);
output.writeBytes(query);
output.close();
os.close();

Check Server service validity with other technology and/or classic java. You didn say in your question if you succeed to discriminate the server from the issue.
from java doc ...getResponseCode returns -1 if no code can be discerned from the response (i.e., the response is not valid HTTP).
Java https post request example : http://www.java-samples.com/java/POST-toHTTPS-url-free-java-sample-program.htm
try to close your outputstream after querying the status and not before...that may help

Here is how you should send POST requests in Android
HttpPost httpGet = new HttpPost(server + "/login?email="+username+"&password="+password);
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpResponse response = httpClient.execute(httpGet);
You can read response using:
response.getEntity().getContent()

Android: Gzip/Http supported by default?

I am using the code shown below to get Data from our server where Gzip is turned on. Does my Code already support Gzip (maybe this is already done by android and not by my java program) or do I have to add/change smth.? How can I check that it's using Gzip? For my opionion the download is kinda slow.
private static InputStream OpenHttpConnection(String urlString) throws IOException {
InputStream in = null;
int response = -1;
URL url = new URL(urlString);
URLConnection conn = url.openConnection();
if (!(conn instanceof HttpURLConnection))
throw new IOException("Not an HTTP connection");
try {
HttpURLConnection httpConn = (HttpURLConnection) conn;
httpConn.setAllowUserInteraction(false);
httpConn.setInstanceFollowRedirects(true);
httpConn.setRequestMethod("GET");
httpConn.connect();
response = httpConn.getResponseCode();
if (response == HttpURLConnection.HTTP_OK) {
in = httpConn.getInputStream();
if(in == null)
throw new IOException("No data");
}
} catch (Exception ex) {
throw new IOException("Error connecting");
}
return in;
}

Any modern http lib support Gzip compression, it's part of a standard for ages.
But you may need to send header : "Accept-Encoding: gzip"
You can check if it's really works using sniffer in your LAN, or on the Server. You can also check response headers, but that would require code changes (most likely, you will have to turn on gzip on your webserver).
Also, you may download 10Mb file of spaces. With gzip on it would be waaaaay faster :-)

When you using HttpURLConnection class to work with HTTP protocol "Accept-Encoding: gzip" field will automatically added to outgoing requests, and will handled the corresponding response.
(see documentation)

Android InputStream following a rewriterule

I'm trying to parse an xml file from a website. Let's say the website is "http://example.com"
This website has a htaccess rewrite rule setup to redirect anything with a "www" prefix to the host back to example.com. so "http://www.example.com" would redirect to "http://example.com"
In my code I have a URL that i get the InputStream of.
protected InputStream getInputStream() {
try {
return feedUrl.openConnection().getInputStream();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
In this case feedUrl is poingting to "http://www.example.com/file.xml" and when I do the following:
try {
Xml.parse(this.getInputStream(), Xml.Encoding.UTF_8, root.getContentHandler());
} catch (Exception e) {
throw new RuntimeException(e);
}
I get an exception thrown and I believe it's not redirecting to "http://example.com/file.xml"
I could obviously just statically change where my feedUrl variable is pointing to, but I need this to be dynamic.

If anyone ran into this problem like I did, then here's the solution. The HttpURLConnection is already setup to follow redirects by default if the response code is 300, 301, 302, or 303.
For some reason, the server I'm parsing from needs to have the response code be 307 which Android does not redirect automatically.
I would suggest using a different response code, but if your server needs it then here's work around.
HttpURLConnection conn = (HttpURLConnection) feedUrl.openConnection();
int responseCode = conn.getResponseCode();
if( responseCode == 307 ){
String location = conn.getHeaderField("location");
feedUrl = new URL(location);
conn = (HttpURLConnection) this.feedUrl.openConnection();
}
Now conn can open an input stream to the correct file.