发生超时时出错

Question

我现在正在构建的应用程序在使用HTTP帖子时出现问题。发生超时时，应用程序崩溃并显示以下错误：

06-20 19:01:35.715: E/Timeout Exception:(3802): java.net.SocketTimeoutException
06-20 19:01:35.720: W/dalvikvm(3802): threadid=15: thread exiting with uncaught exception (group=0x40c4d1f8)
06-20 19:01:35.865: D/dalvikvm(3802): GC_CONCURRENT freed 67K, 18% free 13640K/16519K, paused 7ms+3ms
06-20 19:01:35.870: E/AndroidRuntime(3802): FATAL EXCEPTION: AsyncTask #4
06-20 19:01:35.870: E/AndroidRuntime(3802): java.lang.RuntimeException: An error occured while executing doInBackground()
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.os.AsyncTask$3.done(AsyncTask.java:278)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.lang.Thread.run(Thread.java:856)
06-20 19:01:35.870: E/AndroidRuntime(3802): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.os.Handler.<init>(Handler.java:121)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.app.Dialog.<init>(Dialog.java:107)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.app.AlertDialog.<init>(AlertDialog.java:114)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.app.AlertDialog$Builder.create(AlertDialog.java:913)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.app.AlertDialog$Builder.show(AlertDialog.java:931)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at com.on_d_mand.live_evenementen.Helper.showAlert(Helper.java:357)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at com.on_d_mand.live_evenementen.SyncData.doInBackground(SyncData.java:99)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at com.on_d_mand.live_evenementen.SyncData.doInBackground(SyncData.java:1)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at android.os.AsyncTask$2.call(AsyncTask.java:264)
06-20 19:01:35.870: E/AndroidRuntime(3802):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
06-20 19:01:35.870: E/AndroidRuntime(3802):     ... 5 more

这是源的样子：

//ON PRE EXECUTE
protected void onPreExecute(){
    if(MESSAGE != null){
        dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        dialog.setMessage(MESSAGE);
        dialog.setIndeterminate(true);
        dialog.setCancelable(false);
        dialog.show();
    }
}
//DO IN BACKGROUND
@Override
protected String doInBackground(String... urls) {
    //SYNC DATA WITH THE SERVER
    try{
        HttpParams httpParameters = new BasicHttpParams();
        // Set the timeout in milliseconds (30 seconds) until a connection is established.
        // The default value is zero, that means the timeout is not used. 
        int timeoutConnection = 30 * 1000;
        HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
        // Set the default socket timeout (SO_TIMEOUT) 
        // in milliseconds (30 seconds) which is the timeout for waiting for data.
        int timeoutSocket = 30 * 1000;
        HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
        HttpClient httpclient = new DefaultHttpClient(httpParameters);
        HttpPost httppost = new HttpPost(urls[0]);
        httppost.setEntity(new UrlEncodedFormEntity(preparedInformation));
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        IS = entity.getContent();
    }catch (SocketTimeoutException ste){
        Log.e("Timeout Exception: ", ste.toString());
    }
    catch(Exception e){
        Log.e("log_tag", "Error in http connection"+e.toString());
    }
    //CONVERT DATA INTO STRING
    try{
        BufferedReader reader = new BufferedReader(new InputStreamReader(IS,"iso-8859-1"),8);
            SB = new StringBuilder();
            SB.append(reader.readLine() + "n");
            String line="0";
            while ((line = reader.readLine()) != null) {
                SB.append(line + "nn");
            }
            IS.close();
            this.result = SB.toString();
    }
    catch(Exception e){
        Log.e("log_tag", "Error converting result "+e.toString());
    }
    return this.result;
}

由 Java RuntimeException...好吧，那又怎样？这个问题需要避免，因为它是我现在拥有的应用程序中的最后一个错误。任何帮助都非常感谢。

Answer 1

你的问题是show()方法。

方法show（）必须从UI线程调用。

您只能在onPogressUpdate()或onPostExecute()中调用此方法，或者在执行任务之前调用show()。另外showAlert()你不能打电话给doInBackground().

您必须知道，您可以调用任何更新UI background thread的内容。因此，要更新您的 UI，请仅使用onProgressUpdate()方法或像我的意思是onPostExecute().

编辑：

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

Answer 2

从doInBackGround()方法中删除helper.showAlert()方法，无法从工作线程在主线程上运行（无法更新主UI线程）。

取而代之的是，使用 onProgressUpdate() 并使用 helper.showAlert（）。

更新：

catch (SocketTimeoutException ste){
        Log.e("Timeout Exception: ", ste.toString());
        return ste.toString();
    }
    catch(Exception e){
        Log.e("log_tag", "Error in http connection"+e.toString());
        return e.toString();
    }

protected void onPostExecute(String result) {
    Toast.makeText(getApplicationContext(), result, Toast.LENGTH_SHORT).show();
 }