发生超时时出错

Question

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

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

源代码如下所示：

//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 + "\n\n");
            }

            IS.close();
            this.result = SB.toString();
    }
    catch(Exception e){
        Log.e("log_tag", "Error converting result "+e.toString());
    }

    return this.result;
}

由 Java RuntimeException 引起...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。非常感谢任何帮助。

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() 中调用此方法或在执行任务之前调用show()。还有showAlert()你不能打电话给doInBackground()。

你必须知道你不能在background thread 中调用更新UI 的任何东西。因此，要更新您的 UI，请仅使用 onProgressUpdate() 方法或我的意思是 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，您不能从工作线程在主线程上运行（不能更新MainUI 线程）。

使用 onProgressUpdate() 并从中使用 helper.showAlert() 来代替它。

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();
 }