CODEWITHSUNDEEP
androidhttp-post
user878813
user878813

Reputation: 795

Async HTTP post android

I am using an application where i just need to download a pair of coordinates for google maps from a mysql server. I can do this successfully using php and a normal httpost but my app freezes for a few seconds when i do it.

I read that you need to make httppost asycronous in order to avoid that freezing until the server finishes the prossess and sends the results.

The point is that i need that results in a json array like the normal httpost.

For example if i had this httppost.

HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://www.yoursite.com/script.php");

try {
    // Add your data
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
    nameValuePairs.add(new BasicNameValuePair("id", "12345"));
    nameValuePairs.add(new BasicNameValuePair("stringdata", "AndDev is Cool!"));
    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

    // Execute HTTP Post Request
    HttpResponse response = httpclient.execute(httppost);
} catch (ClientProtocolException e) {
    // TODO Auto-generated catch block
} catch (IOException e) {
    // TODO Auto-generated catch block
}

String result11 = null;
// convert response to string
try {
    BufferedReader reader = new BufferedReader(new InputStreamReader(is11, "iso-8859-1"), 8);
    StringBuilder sb = new StringBuilder();
    sb.append(reader.readLine() + "\n");
    String line = "0";
    while ((line = reader.readLine()) != null) {
        sb.append(line + "\n");
    }
    is11.close();
    result11 = sb.toString();
} catch (Exception e) {
    Log.e("log_tag", "Error converting result " + e.toString());
}

// parsing data
try {
    JSONArray jArray1 = new JSONArray(result11);
} catch (JSONException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

How can i convert that to an asynchronous post so i can avoid the freeze ?

Upvotes: 2

Views: 20611

Answers (5)

ACC
ACC

Reputation: 2560

Assuming you want to do this on a button click:

public void onClick(View v) {
  new Thread(new Runnable() {
        public void run() {
            //your code here
        }
    }).start();
}

Basically, you are putting IO intensive operation in a separate thread (not your UI thread) so that the UI does not freeze.

Upvotes: 2

koush
koush

Reputation: 2962

Use an async http library like ion. https://github.com/koush/ion

All the threading and asynchronous boilerplate will be handled for you.

This is your same code, asynchronous, using Ion. Much simpler:

Ion.with(context)
.load("http://www.yoursite.com/script.php")
.setBodyParameter("id", "12345")
.setBodyParameter("stringdata", "AndDev is Cool!")
.asJsonArray()
.setCallback(new FutureCallback<JsonArray> {
  void onCompleted(Exception e, JsonArray result) {
    // do something with the result/exception
  }
});

Upvotes: 1

krishnakumarp
krishnakumarp

Reputation: 9295

I suggest using android-async-http ( http://loopj.com/android-async-http/ ) library. It makes android async http calls simple and elegant.

Upvotes: 3

SecStone
SecStone

Reputation: 1753

There is a nice class AsyncTask which can be used to easily run asynchronous tasks. If you embed your code in such a subclass, you might end up with this:

public class FetchTask extends AsyncTask<Void, Void, JSONArray> {
    @Override
    protected JSONArray doInBackground(Void... params) {
        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://www.yoursite.com/script.php");

            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("id", "12345"));
            nameValuePairs.add(new BasicNameValuePair("stringdata", "AndDev is Cool!"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);

            BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            sb.append(reader.readLine() + "\n");
            String line = "0";
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            reader.close();
            String result11 = sb.toString();

            // parsing data
            return new JSONArray(result11);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    @Override
    protected void onPostExecute(JSONArray result) {
        if (result != null) {
            // do something
        } else {
            // error occured
        }
    }
}

You can start the task using:

new FetchTask().execute();

Additional resources:

Upvotes: 5

user932887
user932887

Reputation:

Rather than just starting a new thread, it's a better idea to go with a full-fledged AsyncTask. It provides much greater control of things.

private class DoPostRequestAsync extends AsyncTask<URL, Void, String> {
     protected String doInBackground(URL url) {
        //Your download code here; work with the url parameter and then return the result
        //which if I remember correctly from your code, is a string.
        //This gets called and runs ON ANOTHER thread
     }

     protected void onPostExecute(String result) {
         //This gets called on the interface (main) thread!
         showDialog("Done! " + result);
     }
 }

Place the new class implementation inside of your desired Activity's class. For more info on AsyncTask please follow this link:

http://developer.android.com/reference/android/os/AsyncTask.html

Upvotes: 2

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