Android异步任务方法执行顺序

我使用AsyncTask将一些文件下载到我的应用程序，当我刷新它们时我希望可用文件的列表自行更新。从我在线阅读的部分下载部分将在“doInBackground”方法中完成，之后为了更新视图，我使用了“onPostExecute”方法。当我这样做时，视图不会自行更新，我必须更改活动，然后返回以更新它，这是我用来更新视图的方法，但似乎它在所有文件已完成下载，因此它们不会显示可用文件。Android异步任务方法执行顺序

请纠正我，如果我错了，但不是在doInBackground完全完成后调用onPostExecute？如果没有，我可以做些什么，以便在文件完成下载之前不会调用onPostExecute？

谢谢！

这里是我使用的代码：

private class Documents_Task extends AsyncTask<String, String, Boolean> { 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
     } 

     @Override 
     protected Boolean doInBackground(String... params) { 

      try { 

       // Downloading the documents and savign them 
       return true; 

      } catch (Exception e) { 
       return false; 
      } 
     } 

     @Override 
     protected void onPostExecute(Boolean success) { 

      if (success) { 
       // Displaying the list of available files 
      } 
     } 
    }

编辑：He're用于下载和保存文件

String result = HttpManager.getData(params[0]); 
       // Getting the names of the files I already have on my mobile 
       File folder = (Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS + "/EHTProfs/Documents")); 
       File[] listOfFiles = folder.listFiles(); 

       //String array, each element will correspond to a name of a file on my mobile 
       String[] names = new String[listOfFiles.length]; 

       //Filling my array 
       if (listOfFiles.length > 0) 
        for (int i = 0; i < listOfFiles.length; i++) { 
         if (listOfFiles[i].isFile()) 
          names[i] = listOfFiles[i].getName(); 
        } 

       Context c = Documents.this; 

       // Taking null out of the string result containing the names of the files on my server 
       String sub_result = result.substring(1, result.length() - 6); 

       // Comparing each file name on the server with those on my mobile, 
       // if it exists do nothing, if not download it 
       StringTokenizer st = new StringTokenizer(sub_result, "\",\""); 
       Boolean exists; 

       while (st.hasMoreTokens()) { 
        exists = false; 
        String fileName = st.nextToken(); 
        if (names.length > 0) 
         for (int i = 0; i < names.length; i++) { 
          if (names[i].equals(fileName)) { 
           i = names.length; 
           exists = true; 
          } 
         } 
        if (!exists) { 
         downloadDocument(fileName); 
        } 
       }

的代码下面是下载一个文件

方法

public void downloadDocument(String fileName) { 

     DownloadManager mManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE); 
     Uri downloadUri = Uri.parse("http://" + IP_ADDRESS_PORT + "/EhtprofsWEB/ehtprofs/document/" + fileName); 
     DownloadManager.Request request = new DownloadManager.Request(
       downloadUri) 
       .setAllowedOverRoaming(false) 
       .setTitle(fileName) 
       .setDestinationInExternalPublicDir(
         Environment.DIRECTORY_DOWNLOADS + "/EHTProfs/Documents", fileName); 
     mManager.enqueue(request); 
    }

来源

2015-09-12 Husayn Hakeem

您可能需要做出详细的下载/保存代码。 – headuck

@headuck我添加了代码 –