如何從內部存儲文件安裝應用程序

Question

我試圖下載一個apk文件，然後安裝它。
我已經做了一個外部存儲目錄，但是當我在本地目錄中下載文件時，我無法解析它。

這裏是onCreate方法

final DownloadTask downloadTask = new DownloadTask(this);  
downloadTask.execute("http://file.appsapk.com/wp-content/uploads/apps-2/Gmail.apk","Gmail.apk"); 

代碼DownloadTask是從的AsyncTask延伸的類。 這裏是後臺任務：

@Override 
    protected String doInBackground(String... sUrl) { 
     file_name=sUrl[1]; 
     Boolean isSDPresent = android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED); 
     if (isSDPresent) { 
      directory = new File(Environment.getExternalStorageDirectory()+File.separator+"app_directory"); 
     } 
     else 
     { 
      directory = getFilesDir(); 

     } 
     if (!directory.exists()) 
      directory.mkdirs(); 
     InputStream input = null; 
     OutputStream output = null; 
     HttpURLConnection connection = null; 
     try { 
      URL url = new URL(sUrl[0]); 
      connection = (HttpURLConnection) url.openConnection(); 
      connection.connect(); 
      if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) { 
       return "Server returned HTTP " + connection.getResponseCode() 
         + " " + connection.getResponseMessage(); 
      } 

      int fileLength = connection.getContentLength(); 
      input = connection.getInputStream(); 
      output = new FileOutputStream(directory+"/"+file_name); 
      byte[] buffer = new byte[1024]; 
      long total = 0; 
      int count; 
      while ((count = input.read(buffer)) != -1) { 
       if (isCancelled()) { 
        input.close(); 
        return null; 
       } 
       total += count; 
       if (fileLength > 0) // only if total length is known 
        publishProgress((int) (total * 100/fileLength)); 
       output.write(buffer, 0, count); 
      } 
     } catch (Exception e) { 
      return e.toString(); 
     } finally { 
      try { 
       if (input != null) 
        input.close(); 

       if (output != null) 
        output.close(); 
      } catch (IOException ignored) { 
      } 

      if (connection != null) 
       connection.disconnect(); 
     } 
     return null; 
    } 

這是下載完文件後，第一個運行執行後的方法：

@Override 
    protected void onPostExecute(String result) { 
     mWakeLock.release(); 
     mProgressDialog.dismiss(); 
     if (result != null) 
     { 
      Toast.makeText(context,"Download error: "+result, Toast.LENGTH_LONG).show(); 
     } 
     else 
     { 
      Toast.makeText(context, "File downloaded", Toast.LENGTH_SHORT).show(); 
      File file = new File(directory, file_name); 
      Intent promptInstall = new Intent(Intent.ACTION_VIEW) 
       .setDataAndType(Uri.fromFile(file), 
         "application/vnd.android.package-archive"); 
      context.startActivity(promptInstall); 
      finish(); 

     } 

它與外部存儲完美運行，但它贏得了」與外部運行。爲什麼不？

Answer 1

嘗試使用openfileoutput（）而不是OutputStream將文件保存在內部存儲器中並允許其可讀。 http://developer.android.com/guide/topics/data/data-storage.html#filesInternal。包錯誤主要是由內部存儲的許可引起的。

Answer 2

這是因爲android應用程序無法從另一個應用程序文件讀取它是否使用PRIVATE模式寫入。所以您必須更改文件的模式。我只修改其他部分的onPostExecute（）方法。

try { 
     String tempfile="xyzfile"; 
     File file = new File(directory, file_name); 
     FileInputStream inStream = new FileInputStream(file); 
     FileOutputStream fos = context.openFileOutput(tempfile, 
       context.MODE_WORLD_WRITEABLE | context.MODE_WORLD_READABLE); 

     byte[] buffer = new byte[1024]; 
     int length; 
     // copy the file content in bytes 
     while ((length = inStream.read(buffer)) > 0) { 

      fos.write(buffer, 0, length); 

     } 
     inStream.close(); 
     fos.close(); 
    } catch (FileNotFoundException e) { 
     e.printStackTrace(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
    File file = new File(context.getFilesDir(), tempfile); 
    Intent promptInstall = new Intent(Intent.ACTION_VIEW).setDataAndType(
      Uri.fromFile(file), "application/vnd.android.package-archive"); 
    context.startActivity(promptInstall);