我獲取文件的父目錄不可寫一個SD卡出口

Question

我有這樣的代碼：

public static class ExportDatabaseFileTask extends AsyncTask<String, Void, Boolean> { 
    private Context ctx; 

    /** 
    * 
    */ 
    public ExportDatabaseFileTask(Context ctx) { 
     super(); 
     this.ctx = ctx; 
    } 

    // automatically done on worker thread (separate from UI thread) 
    protected Boolean doInBackground(final String... args) { 

     File dbFile = new File(Environment.getDataDirectory() 
       + "/data/com.mypkg/databases/log.db"); 

     File exportDir = new File(Environment.getExternalStorageDirectory(), ""); 
     if (!exportDir.exists()) { 
      exportDir.mkdirs(); 
     } 
     File file = new File(exportDir, dbFile.getName()); 

     try { 
      file.createNewFile();//* 
      this.copyFile(dbFile, file); 
      return true; 
     } catch (IOException e) { 
      Log.e("mytag", e.getMessage(), e); 
      return false; 
     } 
    } 

    // can use UI thread here 
    protected void onPostExecute(final Boolean success) { 
     if (success) { 
      Toast.makeText(ctx, "Export successful!", Toast.LENGTH_SHORT).show(); 
     } else { 
      Toast.makeText(ctx, "Export failed", Toast.LENGTH_SHORT).show(); 
     } 
    } 

    void copyFile(File src, File dst) throws IOException { 
     FileChannel inChannel = new FileInputStream(src).getChannel(); 
     FileChannel outChannel = new FileOutputStream(dst).getChannel(); 
     try { 
      inChannel.transferTo(0, inChannel.size(), outChannel); 
     } finally { 
      if (inChannel != null) 
       inChannel.close(); 
      if (outChannel != null) 
       outChannel.close(); 
     } 
    } 

} 

論

file.createNewFile(); 

標線，我得到java.io.IOException: Parent directory of file is not writable: /sdcard/log.db

我有一個SD卡安裝，我可以輕鬆地將文件複製到它。什麼可能是錯的？

Answer 1

只是當有人七嘴八舌它犯錯

這是一個缺少權限

<uses-permission 
     android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>