Android ProgressDialog 没有从线程中解散

Question

我正在开发一个 android 应用程序。用户注册过程调用发送电子邮件的服务，因此需要几秒钟，例如 5 或 6 秒，这就是我在线程中执行该任务的原因。问题是，对话框永远不会消失。它保持滚动，用户无能为力。这是我的代码：

try
        {
        final ProgressDialog progDailog = new ProgressDialog(ActividadAltaUsuario.this);

        new Thread(new Runnable() 
        {
        @Override
        public void run()
        {
            try
            {
                URL url = new URL("slowWS");
                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.setRequestMethod("POST");

                InputStream in = new BufferedInputStream(conn.getInputStream());
                String response = IOUtils.toString(in, "UTF-8");
                final JSONObject jsonPrincipal = new JSONObject(response);
                Boolean success = jsonPrincipal.get("status").toString() == "true";

                if (success)
                {
                    ActividadAltaUsuario.this.runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            progDailog.show(ActividadAltaUsuario.this, "Sendind email");
                        }
                    });

                    final String idUsuario = jsonPrincipal.get("idUsuario").toString();
                    URL url2 = new URL("anotherSlowWS");
                    HttpURLConnection conn2 = (HttpURLConnection) url2.openConnection();
                    conn2.setRequestMethod("POST");
                    InputStream in2 = new BufferedInputStream(conn2.getInputStream());
                    String response2 = IOUtils.toString(in2, "UTF-8");
                    JSONObject jsonRtaMail = new JSONObject(response2);
                    //finish();
                }
                else
                {
                    //finish();
                    showToast(jsonPrincipal.get("message").toString());
                }

                ActividadAltaUsuario.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        progDailog.dismiss();
                    }
                });
            }
            catch (Exception e)
            {
                e.printStackTrace();
            } 
        }
        }).start();

        }
        catch(Exception e)
        {
            Log.e("log_tag", "Error in http connection" + e.toString());
        }

有人可以帮助我吗？谢谢！

Answer 1

AsyncTask 将是一种比线程更好的方法，将线程中的网络调用替换为使用 AsyncTask。你可以使用这样的东西

private class LongOperation extends AsyncTask<Void, Void, Void> {

    @Override
    protected String doInBackground(Void... params) {
        //Main stuff that needs to be done in background

    }

    @Override
    protected void onPostExecute(Void result) {
        //Post Execution this method will be called, handle result accordingly
        //You can dismiss your dialog here
    }

    @Override
    protected void onPreExecute() {
        //Do initialization relative stuff here
        // Initialize your dialog here.
    }
}

由于 onPostExecute() 和 onPreExecute() 都在主线程上工作，您可以在此方法中显示和关闭对话框。

Answer 2

UI 控件只能从 UI 线程访问。通常我在扩展 AsyncTask

的 class 中执行此操作

类似于： public class MyTask 扩展了 AsyncTask {

    protected void onPreExecute() {
//create and display your alert here 
    progDialog = ProgressDialog.show(MyActivity.this,"Please wait...", "Logging ...", true);
}

protected Void doInBackground(Void... unused) {

    // here is the thread's work ( what is on your method run()
    ...
    // if we want to show some progress in UI, then call 
    publishProgress(item)
}

protected void onProgressUpdate(Item... item) {
    // theoretically you can show the progress here
}

protected void onPostExecute(Void unused) {
    //dismiss dialog here where the thread has finished his work
    progDialog.dismiss();
}
}

LE: 更多关于 AsyncTask 的细节 https://developer.android.com/reference/android/os/AsyncTask 特别检查受保护的方法

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