如何在postExecute中定义全局变量？

Question

我在AndroidStudio中遇到了postExecute和onReceive的问题。这是我的代码：

public void onReceive(Context context, Intent intent) { 
    super.onReceive(context, intent); 
    remoteViews = new RemoteViews(context.getPackageName(), R.layout.smap_activity); 

    if (MY_BUTTTON_START.equals(intent.getAction())){ 
     new DownloadTask().execute("http://examplepage.net"); 
     RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.smap_activity); 
     Log.d("TAG", "TA" + sms); 
     remoteViews.setTextViewText(R.id.sms, sms); 
     AppWidgetManager.getInstance(context).updateAppWidget(new ComponentName(context, SmapActivity.class), remoteViews); 
    } 

}; 

public class DownloadTask extends AsyncTask<String, Void, String> { 

    @Override 
    protected String doInBackground(String... params) { 
     //do your request in here so that you don't interrupt the UI thread 
     try { 
      return downloadContent(params[0]); 
     } catch (IOException e) { 
      return "Unable to retrieve data. URL may be invalid."; 
     } 
    } 

    @Override 
    public void onPostExecute(String result) { 
     String[] smsCzesci = result.split(" "); 
     Log.d("TAG", smsCzesci[1]); 
     sms = smsCzesci[0]; 
    } 
} 

public String downloadContent(String myurl) throws IOException { 
    InputStream is = null; 
    int length = 500; 

    try { 
     URL url = new URL(myurl); 
     HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
     conn.setReadTimeout(10000 /* milliseconds */); 
     conn.setConnectTimeout(15000 /* milliseconds */); 
     conn.setRequestMethod("GET"); 
     conn.setDoInput(true); 
     conn.connect(); 
     int response = conn.getResponseCode(); 
     is = conn.getInputStream(); 
     // Convert the InputStream into a string 
     String contentAsString = convertInputStreamToString(is, length); 
     return contentAsString; 
    } finally { 
     if (is != null) { 
      is.close(); 
     } 
    } 
} 

public String convertInputStreamToString(InputStream stream, int length) throws IOException, UnsupportedEncodingException { 
    Reader reader = null; 
    reader = new InputStreamReader(stream, "UTF-8"); 
    char[] buffer = new char[length]; 
    reader.read(buffer); 
    return new String(buffer); 
} 

一直是我的变量“SMS” =测试，但在方法postExecute变了，我想要的数据。 我想在onReceive中使用“sms”变量来将widget的文本设置为这个变量，但是onReceive方法这个变量是默认的。

Answer 1

的举动，这需要你的AsyncTask到onPostExecute法的结果代码：

public class DownloadTask extends AsyncTask<String, Void, String> { 
    private final Context context; 

    public DownloadTask(final Context context) { 
    this.context = context; 
    } 

    @Override 
    protected String doInBackground(String... params) { 
    //do your request in here so that you don't interrupt the UI thread 
    try { 
     return downloadContent(params[0]); 
    } catch (IOException e) { 
     return "Unable to retrieve data. URL may be invalid."; 
    } 
    } 

    @Override 
    public void onPostExecute(String result) { 
    String[] smsCzesci = result.split(" "); 
    Log.d("TAG", smsCzesci[1]); 
    sms = smsCzesci[0]; 
    RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.smap_activity); 
    Log.d("TAG", "TA" + sms); 
    remoteViews.setTextViewText(R.id.sms, sms); 
    AppWidgetManager.getInstance(context).updateAppWidget(new ComponentName(context, SmapActivity.class), remoteViews) 
    } 
} 

打电话给你DownloadTask有：

new DownloadTask(context).execute("examplepage.net"); 

Answer 2

onPostExecute就像一个回调。因此，在执行调用之后，您想要执行的任何操作都应写入此方法中。在你的代码中，我将删除DownloadTask类，并写入onReceive方法中的所有内容。像下面这样：

public void onReceive(Context context, Intent intent) { 
    super.onReceive(context, intent); 
    remoteViews = new RemoteViews(context.getPackageName(), R.layout.smap_activity); 

    if (MY_BUTTTON_START.equals(intent.getAction())){ 
     AsyncTask downloadTask = new AsyncTask<String, Void, String>(){ 
      @Override 
      protected String doInBackground(String... params) { 
       //do your request in here so that you don't interrupt the UI thread 
       try { 
        return downloadContent(params[0]); 
       } catch (IOException e) { 
        return "Unable to retrieve data. URL may be invalid."; 
       } 
      } 

      @Override 
      public void onPostExecute(String result) { 
       String[] smsCzesci = result.split(" "); 
       Log.d("TAG", smsCzesci[1]); 
       sms = smsCzesci[0]; 

       RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.smap_activity); 
       Log.d("TAG", "TA" + sms); 
       remoteViews.setTextViewText(R.id.sms, sms); 
       AppWidgetManager.getInstance(context).updateAppWidget(new ComponentName(context, SmapActivity.class), remoteViews); 
      } 
     }; 
     downloadTask.execute("http://examplepage.net"); 
    } 

};