获取Android设备上的所有存储设备
来源:互联网 发布:1吨铀能发多少电 知乎 编辑:程序博客网 时间:2024/05/22 05:14
转自:http://blog.csdn.net/wangsf1112/article/details/51427007
Android系统提供了Environment.getExternalStorageDirectory()接口获得存储设备的路径,但是这个接口往往给出的结果并不是我们想要的,在某些设备上它返回的是手机内部存储,某些设备上返回的手机外部存储。还有就是某些Android设备支持扩展多个sdcard,这个时候想要获得所有存储器的挂载路径,这个接口是没有办法办到的。
那么,Android系统的文件管理器是如何把所有挂载的存储设备加载出来的呢?通过查看文件管理器的源码发现是在MountPointManager类中处理的,通过调用StorageManager类的getVolumeList()方法获取的。
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- public void init(Context context) {
- mStorageManager = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);
- final String defaultPath = getDefaultPath();
- LogUtils.d(TAG, "init,defaultPath = " + defaultPath);
- if (!TextUtils.isEmpty(defaultPath)) {
- mRootPath = ROOT_PATH;
- }
- mMountPathList.clear();
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- StorageVolume[] storageVolumeList = mStorageManager.getVolumeList();
- if (storageVolumeList != null) {
- for (StorageVolume volume : storageVolumeList) {
- MountPoint mountPoint = new MountPoint();
- mountPoint.mDescription = volume.getDescription(context);
- mountPoint.mPath = volume.getPath();
- mountPoint.mIsMounted = isMounted(volume.getPath());
- mountPoint.mIsExternal = volume.isRemovable();
- mountPoint.mMaxFileSize = volume.getMaxFileSize();
- LogUtils.d(TAG, "init,description :" + mountPoint.mDescription + ",path : "
- + mountPoint.mPath + ",isMounted : " + mountPoint.mIsMounted
- + ",isExternal : " + mountPoint.mIsExternal + ", mMaxFileSize: " + mountPoint.mMaxFileSize);
- mMountPathList.add(mountPoint);
- }
- }
- IconManager.getInstance().init(context, defaultPath + SEPARATOR);
- }
系统提供了StorageManager类,它有一个方法叫getVolumeList(),这个方法的返回值是一个StorageVolume数组,StorageVolume类中封装了挂载路径,挂载状态,以及是否可以移除等信息。下面是这个方法的源码。
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- public StorageVolume[] getVolumeList() {
- if (mMountService == null) return new StorageVolume[0];
- try {
- Parcelable[] list = mMountService.getVolumeList();
- if (list == null) return new StorageVolume[0];
- int length = list.length;
- StorageVolume[] result = new StorageVolume[length];
- for (int i = 0; i < length; i++) {
- result[i] = (StorageVolume)list[i];
- }
- return result;
- } catch (RemoteException e) {
- Log.e(TAG, "Failed to get volume list", e);
- return null;
- }
- }
getVolumeList()方法是隐藏的,不能在应用代码中直接调用,所以我们只能通过反射来调用这个方法了。
通过反射机制获取Android设备的所有存储设备
- public class StorageInfo {
- public String path;
- public String state;
- public boolean isRemoveable;
- public StorageInfo(String path) {
- this.path = path;
- }
- public boolean isMounted() {
- return "mounted".equals(state);
- }
- @Override
- public String toString() {
- return "StorageInfo [path=" + path + ", state=" + state
- + ", isRemoveable=" + isRemoveable + "]";
- }
- }
- public static List<StorageInfo> listAllStorage(Context context) {
- ArrayList<StorageInfo> storages = new ArrayList<StorageInfo>();
- StorageManager storageManager = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);
- try {
- Class<?>[] paramClasses = {};
- Method getVolumeList = StorageManager.class.getMethod("getVolumeList", paramClasses);
- Object[] params = {};
- Object[] invokes = (Object[]) getVolumeList.invoke(storageManager, params);
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- if (invokes != null) {
- StorageInfo info = null;
- for (int i = 0; i < invokes.length; i++) {
- Object obj = invokes[i];
- Method getPath = obj.getClass().getMethod("getPath", new Class[0]);
- String path = (String) getPath.invoke(obj, new Object[0]);
- info = new StorageInfo(path);
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- Method getVolumeState = StorageManager.class.getMethod("getVolumeState", String.class);
- String state = (String) getVolumeState.invoke(storageManager, info.path);
- info.state = state;
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- Method isRemovable = obj.getClass().getMethod("isRemovable", new Class[0]);
- info.isRemoveable = ((Boolean) isRemovable.invoke(obj, new Object[0])).booleanValue();
- storages.add(info);
- }
- }
- } catch (Exception e) {
- e.printStackTrace();
- }
- storages.trimToSize();
- return storages;
- }
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- public static List<StorageInfo> getAvaliableStorage(List<StorageInfo> infos){
- List<StorageInfo> storages = new ArrayList<StorageInfo>();
- for(StorageInfo info : infos){
- File file = new File(info.path);
- if ((file.exists()) && (file.isDirectory()) && (file.canWrite())) {
- if (info.isMounted()) {
- storages.add(info);
- }
- }
- }
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- return storages;
- }
调用上述方法:
- List<StorageInfo> list = listAllStorage(this);
- for(StorageInfo info : list){
- Log.e(TAG, info.toString());
- }
- Log.e(TAG, "-----------------");
- List<StorageInfo> infos = getAvaliableStorage(list);
- for(StorageInfo info : infos){
- Log.e(TAG, info.toString());
- }
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- Log.e(TAG, "Environment.getExternalStorageDirectory(): " + Environment.getExternalStorageDirectory());
连上手机进行验证,输出Log信息:
可以看到,通过listAllStorage()方法获取到了手机上的所有存储设备,通过getAvaliableStorage()方法的过滤获取到了挂载状态的所有存储设备。由于该手机只有一个可读写的存储设备,因此与Environment.getExternalStorageDirectory()方法获取到的结果一致。
注意:由于在getAvaliableStorage()方法中我们获取的是可写(canWrite)的设备,需要加上相应权限: <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> ,否则获取不到存储设备。