Android存储设备(U盘,SD卡)状态监测

我们是以DV6300-T的平台来做测试的，发现有2种方式来检测android中external media(包括SD卡,USB)的状态。一种是使用StorageListener监听，还有一种是使用广播的方式。 DV6300-T的存储设备相关分析：相关的类主要有:RecordDeviceManager   DeviceStateListener  ChoiceRecordDevice主要采用了观察者模式对设备拔插的监控来触发各种不同情况：比如在DTVLauncher中就增加了观察者mRecordDeviceListener，在检测到设备拔出时候会停止时移或录制等。 第一种监测方式：使用StorageManager  IMountService  StorageEventListener等类来控制(可以参考DV6300-T的源码): StorageManager mStorageManager = (StorageManager)context.getSystemServic(Context.STORAGE_SERVICE);mStorageManager.registerListener(mStorageListener);IMountService mMountService = IMountService.Stub.asInterface(ServiceManager.getService("mount"));StorageEventListener mStorageListener = new StorageEventListener() {    @Override    public void onStorageStateChanged(String path, String oldState,String newState) {        if(path.equals(mRecordDeviceStorageName)) {        Log.i("usb",path+":"+oldState+"--->"+"newState");                                 if(newState.equals(Environment.MEDIA_UNMOUNTED)) {                notifyObservers();            }        }  }};我们可以根据onStorageStateChanged方法中的3个参数来判断当前的状态，根据path路径来判断是SD卡(/mnt/sdcard)还是USB设备(/mnt/sda)。比如在DV6300-T上，我们打印如下：插SD卡：会调用3次onStorageStateChanged：参数分别是:/mnt/sdcard/extend_sd : removed--->unmounted/mnt/sdcard/extend_sd : unmounted--->checking/mnt/sdcard/extend_sd : checking--->mounted插U盘：/mnt/sda1 :unmounted--->checking/mnt/sda1 :checking--->mounted拔SD卡:/mnt/sdcard/extend_sd : mounted--->unmounted/mnt/sdcard/extend_sd : unmounted--->removed拔U盘：/mnt/sda1 :mounted--->unmounted/mnt/sda1 :unmounted--->removed/mnt/sda1 :removed--->unmounted  第2种监测方式(广播方式):class UsbReceiver{   private BroadcastReceiver mReceiver;   UsbReceiver(Context context){      mReceiver = new BroadcastReceiver(){      @Override      public void onReceive(Context context, Intent intent) {         //intent.getAction());获取存储设备当前状态                 Log.i("usb","BroadcastReceiver:"+intent.getAction());         //intent.getData().getPath());获取存储设备路径         Log.i("usb","path:"+intent.getData().getPath());        }     };        IntentFilter filter = new IntentFilter();      filter.addAction(Intent.ACTION_MEDIA_SHARED);//如果SDCard未安装,并通过USB大容量存储共享返回      filter.addAction(Intent.ACTION_MEDIA_MOUNTED);//表明sd对象是存在并具有读/写权限      filter.addAction(Intent.ACTION_MEDIA_UNMOUNTED);//SDCard已卸掉,如果SDCard是存在但没有被安装      filter.addAction(Intent.ACTION_MEDIA_CHECKING);  //表明对象正在磁盘检查      filter.addAction(Intent.ACTION_MEDIA_EJECT);  //物理的拔出 SDCARD      filter.addAction(Intent.ACTION_MEDIA_REMOVED);  //完全拔出      filter.addDataScheme("file"); // 必须要有此行，否则无法收到广播         context.registerReceiver(mReceiver, filter); }}通过广播传递过来的intent.getData()会得到一个uri，然后uri.getPath()就是插上usb的路径，可以记录下每次插上或者拔出的usb的路径，比如我们在DV6300平台上：U盘就返回/mnt/sda1，而SD卡返回/mnt/sdcard/extend_sd而getAction会获取当前状态，如下描述:U盘插入：intent.getAction() == android.intent.action.MEDIA_UNMOUNTEDintent.getAction() == android.intent.action.MEDIA_CHECKINGintent.getAction() == android.intent.action.MEDIA_MOUNTEDU盘拔出：intent.getAction() == android.intent.action.MEDIA_EJECTintent.getAction() == android.intent.action.MEDIA_UNMOUNTEDintent.getAction() == android.intent.action.MEDIA_UNMOUNTEDintent.getAction() == android.intent.action.MEDIA_REMOVEDintent.getAction() == android.intent.action.MEDIA_UNMOUNTEDSD卡插入:intent.getAction() == android.intent.action.MEDIA_UNMOUNTEDintent.getAction() == android.intent.action.MEDIA_CHECKINGintent.getAction() == android.intent.action.MEDIA_MOUNTEDSD卡拔出:intent.getAction() == android.intent.action.MEDIA_EJECTintent.getAction() == android.intent.action.MEDIA_UNMOUNTEDintent.getAction() == android.intent.action.MEDIA_UNMOUNTEDintent.getAction() == android.intent.action.MEDIA_REMOVED   参考博文：android 监控usb插拔Android 框架层为IMountService 增加新接口android usb挂载分析---MountService启动Android深入浅出之Binder机制Android 2.3 SD卡挂载流程浅析(七)
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