Make a call synchronously with loopj Android Asynchronous Http Client

Question

I'm trying to use setUseSynchronousMode on loopj to wait for results of http call before continuing in one case. I tried:

    AsyncHttpResponseHandler responseHandler = new AsyncHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, byte[] response) {
            Log.d("TEST", "Got results");
        }
    };

    AsyncHttpClient client = new AsyncHttpClient();
    responseHandler.setUseSynchronousMode(true);
    client.get("http://www.google.com", responseHandler);
    Log.d("TEST", "Don't want to get here until after getting results");

But the result is:

07-11 19:48:05.631 D/TEST﹕ Don't want to get here until after getting results
07-11 19:48:05.814 D/TEST﹕ Got results

Am I misunderstanding what setUseSynchronousMode should do?

Whether that's what synchronous mode does or not, its NOT anything you should ever do. It will freeze up your entire UI thread and make the phone unresponsive. There's a reason why HTTP requests have to be done on another thread, don't try to work around it. — Gabe Sechan, Jul 12 '14 at 06:48

score 5 · Accepted Answer · edited Sep 18 '17 at 04:20

5

You should have used SyncHttpClient instead of AsyncHttpClient. setUseSynchronousMode doesn't have the desired effect for AsyncHttpClient.

edited Sep 18 '17 at 04:20

Zapnologica

22,170
44
158
253

answered Jul 13 '14 at 22:03

Edwin Evans

2,726
5
34
47

Could you share a sample code? `SyncHttpClient` doesn't seem to block the thread it is running on and this stops me from cancelling the request. – Sufian Oct 27 '14 at 05:40
First off, I did end up using AsyncHttpClient with callback as this really was a cleaner approach so you may want to think some more about doing it that way. But I think if you use SyncHttpClient (perhaps need to call responseHandler.setUseSynchronousMode(true)) also it should work. I'm not surprised it doesn't support canceling the request though. – Edwin Evans Oct 27 '14 at 15:20

score 2 · Answer 2 · answered Oct 29 '14 at 10:46

To have synchronous version of AsyncHttpClient with an ability to cancel it, I do everything on the main thread. Previously I was running it in AsyncTask and as soon as AsyncHttpClient.post() was called, the AsyncTask would finish and I was unable to keep track the AsyncHttpClient instance.

SyncHttpClient didn't allow me to cancel the uploading so I knew I had to use AsyncHttpClient and make appropriate changes.

Following is my class to upload a file which uses AsyncHttpClient and allows cancellation:

public class AsyncUploader {
    private String mTitle;
    private String mPath;
    private Callback mCallback;

    public void AsyncUploader(String title, String filePath, MyCallback callback) {
        mTitle = title;
        mPath = filePath;
        mCallback = callback;
    }

    public void startTransfer() {
        mClient = new AsyncHttpClient();
        RequestParams params = new RequestParams();
        File file = new File(mPath);
        try {
            params.put("title", mTitle);
            params.put("video", file);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        mClient.setTimeout(50000);
        mClient.post(mContext, mUrl, params, new ResponseHandlerInterface() {
            @Override
            public void sendResponseMessage(HttpResponse response) throws IOException {
                HttpEntity entity = response.getEntity();
                if (entity != null) {
                    InputStream instream = entity.getContent();
                    // TODO convert instream to JSONObject and do whatever you need to
                    mCallback.uploadComplete();
                }
            }
            @Override
            public void sendProgressMessage(int bytesWritten, int bytesTotal) {
                mCallback.progressUpdate(bytesWritten, bytesTotal);
            }
            @Override
            public void sendFailureMessage(int statusCode, Header[] headers, byte[] responseBody, Throwable error) {
                mCallback.failedWithError(error.getMessage());
            }
        });
    }

    /**
    * Cancel upload by calling this method
    */
    public void cancel() {
        mClient.cancelAllRequests(true);
    }
}

This is how you can run it:

AsyncUploader uploader = new AsyncUploader(myTitle, myFilePath, myCallback);
uploader.startTransfer();
/* Transfer started */
/* Upon completion, myCallback.uploadComplete() will be called */

To cancel the upload, just call cancel() like:

uploader.cancel();

Make a call synchronously with loopj Android Asynchronous Http Client

2 Answers2

Linked