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How to send many/multiple post requests of JSONObjects on Android?

There's a lot of questions on StackOverflow for sending a single POST request on Android, but none of them cover cases where you're receiving lots of data from a sensor connected to your phone and need to Post Request that data as you receive it.
I'm receiving data from a sensor connected to my Android, and need to to send it to a Flask server hosted on Heroku.
public void sendToFlask(JSONObject jsonParam) {
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try {
URL url = new URL("URLHERE");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
conn.setRequestProperty("Accept","application/json");
conn.setDoOutput(true);
conn.setDoInput(true);
Log.i("JSON", jsonParam.toString());
DataOutputStream os = new DataOutputStream(conn.getOutputStream());
//os.writeBytes(URLEncoder.encode(jsonParam.toString(), "UTF-8"));
os.writeBytes(jsonParam.toString());
os.flush();
os.close();
Log.i("STATUS", String.valueOf(conn.getResponseCode()));
Log.i("MSG" , conn.getResponseMessage());
conn.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
});
This code unfortunately errors out for creating too many files
I understand that the solution here may be to use a global HttpURLConnection but unfortunately that also gives me the error of java.net.ProtocolException: cannot write request body after response has been read This happens after I move the conn and url variables to global scope and set them in onCreate

GCM Push Notifications are not delivered to devices

We (Panos and Rainer - see the comments down) have a server and several Android devices.
We want to send push notifications from our server via GCM to the Android devices.
Now we make a post request to the GCM server. The GCM server response is that all is fine (success==1 and even the message-id)!
BUT the push notification(s) are never delivered to the devices.
If we use the same data and the Chrome addon Postman - the notifications are delivered immediately.
We tried all lot of different solutions. We get always the feedback of the GCM server that all is ok - but the push notifications aren't send.
We also tried this one:
https://github.com/googlesamples/google-services/blob/master/android/gcm/gcmsender/src/main/java/gcm/play/android/samples/com/gcmsender/GcmSender.java

You might also post the URL you use. There is a new GCM enpoint which looks like the following:
https://gcm-http.googleapis.com/gcm/send
I am not yet sure what's causing the issues on your side. But the following is tested and working:
public class Main {
public static void main(String[] args) {
// write your code here
try {
String url = "https://gcm-http.googleapis.com/gcm/send";
URL obj = new URL(url);
HttpsURLConnectionImpl conn = (HttpsURLConnectionImpl) obj.openConnection();
conn.setRequestProperty("Content-Type", "application/json");
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty ("Authorization", "key=***");
String title = "Short title";
String body = "A body :D";
String token = "****";
String data = "{ \"notification\": { \"title\": \"" + title +"\", \"body\": \"" + body + "\" }, \"to\" : \"" + token + "\", \"priority\" : \"high\" }";
OutputStreamWriter out = new OutputStreamWriter(conn.getOutputStream());
out.write(data);
out.close();
String text = getText(new InputStreamReader(conn.getInputStream()));
System.out.println(text);
} catch (Exception e) {
e.printStackTrace();
}
}
public static String getText(InputStreamReader in) throws IOException {
StringBuilder sb=new StringBuilder();
BufferedReader br = new BufferedReader(in);
String read;
while((read=br.readLine()) != null) {
sb.append(read);
}
br.close();
return sb.toString();
}
}

This is the data used for the Postman request which is working without any problem.
Rainer already mentioned that we tried several implementations on the Java side and it seems that we are always able to communicate with the service and receive a response which seems to look correct so far:
{
"multicast_id":7456542468425129822,
"success":1,
"failure":0,
"canonical_ids":0,
"results":
[{
"message_id":"0:1457548597263237%39c590d7f9fd7ecd"
}]
}

Not sure if I'm on the right track but do you mean downstream HTTP messages (plain text)?
Tried to send the following JSON to the service (from Postman) which results again in a positive response but this time the notification did not reach the device (just to make that clear, at the moment there is no app on the device listening actively for incoming notifications -> first of all we just want to ensure that they generally arrive on the device):
{
"data":
{
"score": "5x1",
"time": "15:10"
},
"to" : "SECRET-DEVICE-TOKEN"
}

Thanks to all of you trying to help here but to be honest, this issue is really frustrating. Communicating with an interface\service which seems not to be able to return a useful response in case the request contains maybe evil stuff which will finally prevent GCM from sending the push notification to the device, feels like a pain in the ass. If Postman would also fail I would say ok, you can not be so stupid :-)
Here are some quick'n dirty implementations we have already used.
Example
try
{
URL url = new URL(apiUrl);
HttpsURLConnection conn = (HttpsURLConnection);//also tried HttpURLConnection
url.openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("Authorization", "key="+apiKey);
conn.setDoOutput(true);
String json = "{\"priority\":\"high\",\"notification\":{\"title\":\"Some title\",\"text\":\"Some text\"},\"to\":\""+deviceToken+"\"}";
OutputStream os = conn.getOutputStream();
os.write(json.getBytes());
os.flush();
}
catch(Exception exc)
{
System.out.println("Error while trying to send push notification: "+exc);
}
Example
HttpClient httpClient = HttpClientBuilder.create().build();
try
{
HttpPost request = new HttpPost(apiUrl);
StringEntity params =new StringEntity("{\"priority\":\"high\",\"notification\":{\title\":\"Some title\",\"text\":\"Some text\"},\"to\":\""+deviceToken+"\"}");
request.addHeader("Content-Type", "application/json");
request.addHeader("Authorization", "key="+apiKey);
request.setEntity(params);
HttpResponse response = httpClient.execute(request);
// check response
System.out.println(response.getStatusLine().toString());
}catch (Exception exc) {
System.out.println("Error while trying to send push notification: "+exc);
} finally {
httpClient.getConnectionManager().shutdown(); //Deprecated
}
Example
try
{
String charset = "UTF-8";
URLConnection connection = new URL(apiUrl).openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Accept-Charset", charset);
connection.setRequestProperty("Content-Type", "application/json;charset=" + charset);
connection.setRequestProperty("Authorization", "key="+apiKey);
String param = "{\"priority\":\"high\",\"notification\":{\"title\":\"Some title\",\"text\":\"Some text\"},\"to\":\""+deviceToken+"\"}";
try (OutputStream output = connection.getOutputStream())
{
output.write(param.getBytes(charset));
}
InputStream response = connection.getInputStream();
}
catch(Exception exc)
{
System.out.println("Error while trying to send push notification: "+exc);
}
Example
try
{
// prepare JSON
JSONObject jGcmData = new JSONObject();
JSONObject jData = new JSONObject();
jData.put("message", "{ \"data\": {\"score\": \"5x1\",\"time\": \"15:10\"},\"to\" : \""+deviceToken+"\"}");
jGcmData.put("to", deviceToken);
jGcmData.put("data", jData);
// Create connection to send GCM Message request.
URL url = new URL("https://android.googleapis.com/gcm/send");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty("Authorization", "key=" + apiKey);
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestMethod("POST");
conn.setDoOutput(true);
// Send GCM message content.
OutputStream outputStream = conn.getOutputStream();
outputStream.write(jGcmData.toString().getBytes());
// Read GCM response.
InputStream inputStream = conn.getInputStream();
String resp = IOUtils.toString(inputStream);
System.out.println(resp);
} catch (IOException e) {
System.out.println("Unable to send GCM message. "+e);
}

Mike, with your example it's working also on our side. After comparing your implementation with the on eon our side, the only real difference I found is the used URL!!
Somehow the URL used in our Java implementation was https://android.googleapis.com/gcm/send
Seems that https://gcm-http.googleapis.com/gcm/send is the right one which by the way was also used for our Postman tests.
But why on hell is the URL from our failed tests still somehowe valid and returns a response!?

Setting the priority to high in the json resolved the issue for me.
'registration_ids' => $id,
'priority' => 'high',
'data' => $load

For our case, the clients Android devices had intermittent internet connection issue, that is, network dropouts thus causing notification delivery failed. We resolved the reliability issue with the following JAVA GCM code:
gcmPayload.setTime_to_live(messageExpiryTime); //in seconds. Set notification message expiry to give user time to receive it in case they have intermittent internet connection, or phone was off
gcmPayload.setPriority("high");
and APNS code:
ApnsService apnsService = APNS.newService().withCert(certificateStream, configurations.getApnPassword()).withProductionDestination().build();
PayloadBuilder payloadBuilder = APNS.newPayload();
...
payloadBuilder.instantDeliveryOrSilentNotification(); //same as content-available=true
String payload = payloadBuilder.build();
Integer now = (int)(new Date().getTime()/1000);
//use EnhancedApnsNotification to set message expiry time
for(String deviceToken : deviceTokens) {
EnhancedApnsNotification notification = new EnhancedApnsNotification(EnhancedApnsNotification.INCREMENT_ID() /* Next ID */,
now + messageExpiryTime /* Expiry time in seconds */,
deviceToken /* Device Token */,
payload);
apnsService.push(notification);
}
Also, remember to consider time zone if your backend server time is different to the client mobile app time.

How do I write to an OutputStream using DefaultHttpClient?

How do I get an OutputStream using org.apache.http.impl.client.DefaultHttpClient?
I'm looking to write a long string to an output stream.
Using HttpURLConnection you would implement it like so:
HttpURLConnection connection = (HttpURLConnection)url.openConnection();
OutputStream out = connection.getOutputStream();
Writer wout = new OutputStreamWriter(out);
writeXml(wout);
Is there a method using DefaultHttpClient similar to what I have above? How would I write to an OutputStream using DefaultHttpClient instead of HttpURLConnection?
e.g
DefaultHttpClient client = new DefaultHttpClient();
OutputStream outstream = (get OutputStream somehow)
Writer wout = new OutputStreamWriter(out);

I know that another answer has already been accepted, just for the record this is how one can write content out with HttpClient without intermediate buffering in memory.
AbstractHttpEntity entity = new AbstractHttpEntity() {
public boolean isRepeatable() {
return false;
}
public long getContentLength() {
return -1;
}
public boolean isStreaming() {
return false;
}
public InputStream getContent() throws IOException {
// Should be implemented as well but is irrelevant for this case
throw new UnsupportedOperationException();
}
public void writeTo(final OutputStream outstream) throws IOException {
Writer writer = new OutputStreamWriter(outstream, "UTF-8");
writeXml(writer);
writer.flush();
}
};
HttpPost request = new HttpPost(uri);
request.setEntity(entity);

You can't get an OutputStream from BasicHttpClient directly. You have to create an HttpUriRequest object and give it an HttpEntity that encapsulates the content you want to sent. For instance, if your output is small enough to fit in memory, you might do the following:
// Produce the output
ByteArrayOutputStream out = new ByteArrayOutputStream();
Writer writer = new OutputStreamWriter(out, "UTF-8");
writeXml(writer);
// Create the request
HttpPost request = new HttpPost(uri);
request.setEntity(new ByteArrayEntity(out.toByteArray()));
// Send the request
DefaultHttpClient client = new DefaultHttpClient();
HttpResponse response = client.execute(request);
If the data is large enough that you need to stream it, it becomes more difficult because there's no HttpEntity implementation that accepts an OutputStream. You'd need to write to a temp file and use FileEntity or possibly set up a pipe and use InputStreamEntity
EDIT See oleg's answer for sample code that demonstrates how to stream the content - you don't need a temp file or pipe after all.

This worked well on android. It should also work for large files, as no buffering is needed.
PipedOutputStream out = new PipedOutputStream();
PipedInputStream in = new PipedInputStream();
out.connect(in);
new Thread() {
#Override
public void run() {
//create your http request
InputStreamEntity entity = new InputStreamEntity(in, -1);
request.setEntity(entity);
client.execute(request,...);
//When this line is reached your data is actually written
}
}.start();
//do whatever you like with your outputstream.
out.write("Hallo".getBytes());
out.flush();
//close your streams

I wrote an inversion of Apache's HTTP Client API [PipedApacheClientOutputStream] which provides an OutputStream interface for HTTP POST using Apache Commons HTTP Client 4.3.4.
Calling-code looks like this:
// Calling-code manages thread-pool
ExecutorService es = Executors.newCachedThreadPool(
new ThreadFactoryBuilder()
.setNameFormat("apache-client-executor-thread-%d")
.build());
// Build configuration
PipedApacheClientOutputStreamConfig config = new
PipedApacheClientOutputStreamConfig();
config.setUrl("http://localhost:3000");
config.setPipeBufferSizeBytes(1024);
config.setThreadPool(es);
config.setHttpClient(HttpClientBuilder.create().build());
// Instantiate OutputStream
PipedApacheClientOutputStream os = new
PipedApacheClientOutputStream(config);
// Write to OutputStream
os.write(...);
try {
os.close();
} catch (IOException e) {
logger.error(e.getLocalizedMessage(), e);
}
// Do stuff with HTTP response
...
// Close the HTTP response
os.getResponse().close();
// Finally, shut down thread pool
// This must occur after retrieving response (after is) if interested
// in POST result
es.shutdown();
Note - In practice the same client, executor service, and config will likely be reused throughout the life of the application, so the outer prep and close code in the above example will likely live in bootstrap/init and finalization code rather than directly inline with the OutputStream instantiation.

Http POST in BlackBerry

Greetings,
I am trying to setup a server connection from my BlackBerry Application . I was able to get a response code on the status of the server. Now i have a few values which i have to POST to the server
Its like a registration page values(username, password, age ) have to be sent to the server .
ConnectionFactory connFact = new ConnectionFactory();
ConnectionDescriptor connDesc;
connDesc = connFact.getConnection(url);
if (connDesc != null)
{
HttpConnection httpConn;
httpConn = (HttpConnection)connDesc.getConnection();
try
{
final int iResponseCode = httpConn.getResponseCode();
UiApplication.getUiApplication().invokeLater(new Runnable()
{
public void run()
{
Dialog.alert("Response code: " + Integer.toString(iResponseCode));
}
});
}
catch (IOException e)
{
System.err.println("Caught IOException: " + e.getMessage());
}
}
Thats the code i used to get the response code.
I would appreciate it if someone could help me how i can make a POST request to the server..
the server url for status was company.com/app/version/stats
when it for register it would be
company.com/app/register
Thank you

What type of a POST do you use? If you are just passing key-value pairs, then it should be a POST of a "application/x-www-form-urlencoded" content-type.
So, what lacks youe code is:
1). Set a proper content-type on your connection:
httpConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
2). Prepare the content to be sent to the server via the POST:
URLEncodedPostData encPostData = new URLEncodedPostData("UTF-8", false);
encPostData.append("username", username);
encPostData.append("password", password);
encPostData.append("age", age);
byte[] postData = encPostData.toString().getBytes("UTF-8");
3). Set content-length for the connection (this step may be optional - try without this first, probably the BB OS is smart enough to set this automatically):
httpConn.setRequestProperty("Content-Length", String.valueOf(postData.length));
4). Open an OutputStream and write the content to it (the code is simplified):
OutputStream os = httpConn.openOutputStream();
os.write(postData);
os.flush();

...
httpConn = (HttpConnection)connDesc.getConnection();
httpConn.setRequestMethod(HttpConnection.POST);
httpConn.setRequestProperty("username",name);
httpConn.setRequestProperty("password",pass);
....

The correct way to PUT a JSON object to a RESTful server

I am having trouble correctly formatting my PUT request to get my server to recognise my client application's PUT command.
Here is my section of code that puts a JSON string to the server.
try {
URI uri = new URI("the server address goes here");
URL url = uri.toURL();
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter out = new OutputStreamWriter(conn.getOutputStream());
out.write(gson.toJson(newClient));
out.close();
} catch (Exception e) {
Logger.getLogger(CATHomeMain.class.getName()).log(Level.SEVERE, null, e);
}
and here is the code that is supposed to catch the PUT command
#PUT
#Consumes("text/plain")
public void postAddClient(String content, #PathParam("var1") String var1, #PathParam("var2") String var2) {
What am I doing wrong?

You also need to tell the client side that it is doing a PUT of JSON. Otherwise it will try to POST something of unknown type (the detailed server logs might record it with the failure) which isn't at all what you want. (Exception handling omitted.)
URI uri = new URI("the server address goes here");
HttpURLConnection conn = (HttpURLConnection) uri.toURL().openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("PUT");
conn.addRequestProperty("Content-Type", "application/json");
OutputStreamWriter out = new OutputStreamWriter(conn.getOutputStream());
out.write(gson.toJson(newClient));
out.close();
// Check here that you succeeded!
On the server side, you want that to declare that it #Consumes("application/json") of course, and you probably want the method to either return a representation of the result or redirect to it (see this SO question for a discussion of the issues) so the result of your method should not be void, but rather either a value type or a JAX-RS Response (which is how to do the redirect).

Probably the MIME type. Try "application/json".