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