NetworkOnMainThreadException with AsyncTask

问题

I need to do some HTTP requests from my android app. I use AsyncTask as needed, with the network part in doInBackground.

Here is my request class :

public class AsyncRequest extends AsyncTask<Void, Integer, HttpResponse>{

private     ProgressDialog  dialog;
private     Activity        activity;
private     HttpUriRequest  query;
private     HttpClient      client;
private     HttpResponse    response;
private     String          dialogMsg;
private     String          uri;

public String getUri() {
    return uri;
}

public void setUri(String uri) {
    this.uri = uri;
}

public AsyncRequest(Activity a, HttpUriRequest q, HttpClient c, String m) {
    query = q;
    client = c;
    activity = a;
    dialog = new ProgressDialog(a);
    dialogMsg = m;
}

@Override
protected void onPostExecute(HttpResponse res) {
    if (dialog.isShowing())
        dialog.dismiss();
}

protected void onPreExecute() {
    this.dialog.setMessage(dialogMsg);
    this.dialog.show();
}

@Override
protected HttpResponse  doInBackground(Void... arg0) {
    try {
        response = client.execute(query);
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }       
    return response;
}

protected   HttpResponse    getResponse() {
    return response;
}
}

And, in my UI thread, I use it this way :

AsyncRequest        request;
    HttpClient          httpClient = new DefaultHttpClient();
    HttpGet             getQuery = new            HttpGet("Here goes my url");
    HttpResponse        response = null;
    String              rt = "Null";
    getQuery.setHeader("Authorization",    getIntent().getExtras().getString("token"));

    request = new AsyncRequest(this, getQuery, httpClient, "Loading events...");
    try {
        response =  request.execute().get(3, TimeUnit.SECONDS);
    } catch (Exception e) {
        e.printStackTrace();
    }
    HttpEntity entity = response.getEntity();
    try {
        rt = EntityUtils.toString(entity);
    } catch (Exception e) {
             e.printStackTrace();
        return ;
    }

So, I'm an android beginner, but I guess this exception is caught when network related code is executed in main thread. But I run client.execute() in my doInBackground() method. Is it the call to execute().get() (in ui thread) that causes the problem ?

回答1:

You have this

response =  request.execute().get(3, TimeUnit.SECONDS);

Calling get() makes AsyncTask no more Asynchronous. It blocks the ui thread waiting for the response. This leads to NetworkOnMainThreadException.

Get rid of get(3, TimeUnit.SECONDS);

Just use request.execute(). You can update ui in onPostExecute. You can also use interface as a callback to the Activity.

Check the answer by blackbelt in the below link

How do I return a boolean from AsyncTask?

来源：https://stackoverflow.com/questions/22757607/networkonmainthreadexception-with-asynctask

标签

android