读写SD卡权限：

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

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

读写SD卡 Environment.MEDIA_MOUNTED /mnt/sdcard目录才是可读可写

String state;

String path;

state = Environment.getExternalStorageState();

if(state.equals(Environment.MEDIA_MOUNTED))｛

path = Environment.getExternalStorageDirectory().getAbsolutePath();

｝