android API 23以后 对SD卡上的文件进行读写操作需要额外判断

参考：https://stackoverflow.com/questions/8854359/exception-open-failed-eacces-permission-denied-on-android/13569364#13569364

android-23对SD卡上操作不仅要在AndroidManifset.xml文件进行下面的权限设置：

<!-- SDCard中创建与删除文件权限 --> <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/> <!-- 向SDCard写入数据权限 --> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

还要对SD卡进行判断，

// 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 ); } }