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