安装SD卡： action=android.intent.action.MEDIA_CHECKING
action = android.intent.action.MEDIA_MOUNTED
卸载SD卡：android.intent.action.MEDIA_UNMOUNTED
未卸载直接拔出SD卡：action=android.intent.action.MEDIA_BAD_REMOVAL
卸载后拔出SD卡：action=android.intent.action.MEDIA_REMOVED
卸载或直接拔出SD卡：action=android.intent.action.MEDIA_EJECT