caused by android.system.errnoexception open failed eacces (permission denied)解决方案，安卓6.0（API23）权限问题

在API23+以上，不止要在AndroidManifest.xml里面添加权限

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

还要在JAVA代码中请求权限：

// Storage Permissions
   private static final int REQUEST_EXTERNAL_STORAGE = 1;
   private static String[] PERMISSIONS_STORAGE = {
           Manifest.permission.READ_EXTERNAL_STORAGE,
           Manifest.permission.WRITE_EXTERNAL_STORAGE};

   /**
    * * Checks if the app has permission to write to device storage
    * *
    * * If the app does not has permission then the user will be prompted to
    * * grant permissions
    * *
    * * @param activity
    */
   public static void verifyStoragePermissions(Activity activity) {
       // Check if we have write permission
       int permission = ActivityCompat.checkSelfPermission(activity,
               Manifest.permission.WRITE_EXTERNAL_STORAGE);

       if (permission != PackageManager.PERMISSION_GRANTED) {
           // We don't have permission so prompt the user
           ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
                   REQUEST_EXTERNAL_STORAGE);
       }
   }

在保存的方法前面调用即可

官方文档：http://developer.android.com/training/permissions/requesting.html