Do POST request with Android DefaultHTTPClient cause freeze on execute()

I need post data to server. I use this code:

HttpClient client = new DefaultHttpClient();
try {

    HttpPost httppost = new HttpPost(serverUrl);

    StringEntity se = new StringEntity(data);
    httppost.setEntity(se);
    httppost.setHeader("Accept", "application/json");
    httppost.setHeader("Content-type", "application/json");

    // Execute HTTP Post Request
    HttpResponse response = client.execute(httppost);
    int statusCode = response.getStatusLine().getStatusCode();
    Log.i(TVProgram.TAG, "ErrorHandler post status code: " + statusCode);

} catch (Exception e) {
    e.printStackTrace();
} finally {
    if (client != null) {
        client.getConnectionManager().shutdown();
    }
}

But problem is that Android freeze on execute() method, application is blocked out and after some time Android tel开发者_如何学Gol me that application doesn't respond.

I tried to debug into SDK classes and it freeze in AbstractSessionInputBuffer class on the line 103 which is

l = this.instream.read(this.buffer, off, len);

I also tried it run the request in separated thread, but the same problem.

I tested it on Android 2.1 (emulator) and Android 2.2 real mobile device.

I also tried to set HTTP proxy and use Fiddler to check HTTP communication data are received by server and server also send correct answer and HTTP code 200. All seems to be ok.

What is wrong please?

UPDATE: When I use AndroidHttpClient which is part of Android 2.2 SDK it works great. But it is not in earlier version of Android. So I include it's source code in my app for now. But AndroidHttpClient use DefaultHTTPClient internally, so problem will be in configuration of DefaultHttpClient.

I am using a POST HTTP request successfully. Here is my code. I removed pieces using handler to display messages etc. and the handler itself. The POST string is like "&NAME=value@NAME2=value2"...

protected class ConnectingThread implements Runnable
{          
    Message msg;
    private Handler mExtHandler;
    private String mData;
    private String mUrl;

    /** 
     * @param h (Handler) - a handler for messages from this thread
     * @param data (String) - data to be send in HTTP request's POST
     * @param url (String) - URL to which to connect
     */
    ConnectingThread(Handler h, String data, String url) {
        mExtHandler = h;
        mData = data;
        mUrl = url;
    }

    public void run() {         
        try {
            // TODO use the handler to display txt info about connection

            URL url = new URL(mUrl);
            URLConnection conn = url.openConnection();             
            conn.setConnectTimeout(CONN_TIMEOUT_MILLIS);

            conn.setDoOutput(true);
            BufferedOutputStream wr = new BufferedOutputStream(conn.getOutputStream());                
            wr.write(mData.getBytes());
            wr.flush();
            wr.close();

            String sReturn = null;

            BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            int length = conn.getContentLength();
            char[] buffer = new char[length];
            int read = rd.read(buffer);
            if(read == length)
                sReturn = new String(buffer);
            rd.close();
            buffer = null;   
         // TODO use the handler to use the response

        } catch (Exception e) {
            //....
        }  
        // TODO use the handler to display txt info about connection ERROR   
    }

}           

Isn't client.execute(httppost); synchronous ?

You probably need to put this in a thread, else it will freeze the UI.

Yes it is being freezed just becoz you haven't implemented this as Asynchronous process. Because while it makes web request, your UI will wait for the response and then it will be updated once the response is received.

So this should be implemented as Asynchronous process, and user should be notified (with progress bar or progress dialog) that there is something happening.

Now, Instead of implementing Runnable class, in android its preferrable and recommended to use AsyncTask, its also known as Painless Threading.

• Do you background tasks inside the doInBackground() method.
• Do your display type of operations inside onPostExecute() method, like updating listview with fetched data, display values inside TextViews....etc.
• Display ProgressBar or ProgressDialog inside the onPreExecute() method.

Use AndroidHttpClient helped me in this situation.

But now complete AndroidHttpClient and DefaultHttpClient are obsolete in current version of Android so it is not important now.