1 在Setting應用中，storage 顯示total and free code:

final File path = VolumeInfo.getPath();
final long freeBytes = path.getFreeSpace();
final long totalBytes = path.getTotalSpace();
final long usedBytes = totalBytes - freeBytes;

final String used = Formatter.formatFileSize(context, usedBytes);
final String total = Formatter.formatFileSize(context, totalBytes);

２　VolumeInfo.java 是hidden的，只能通過反射得到。代碼如下：

try {
    StorageManager sManager = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);
    Class class_StorageManager = StorageManager.class;
    Method method_getVolumes = class_StorageManager.getMethod("getVolumes");

    List<Object> volumes = (List<Object>) method_getVolumes.invoke(sManager);

    mClassType = Class.forName("android.os.storage.VolumeInfo");

    for (Object volumeInfo : volumes) {

        mGetMethod = mClassType.getDeclaredMethod("getPath");
        File path = (File) mGetMethod.invoke(volumeInfo);
        final long freeBytes = path.getFreeSpace();
        final long totalBytes = path.getTotalSpace();
        final long usedBytes = totalBytes - freeBytes;

        Log.i("cyy1","freeBytes="+Formatter.formatFileSize(context,freeBytes));

        Log.i("cyy1","usedBytes="+Formatter.formatFileSize(context,usedBytes));

         mGetMethod１ = mClassType.getDeclaredMethod("getId");
        String  id = (String) mGetMethod１.invoke(volumeInfo);
        Log.i("cyy1","id="+id);
    }



}catch (Exception e){
    Log.i("cyy1",e.getMessage());
    e.printStackTrace();
}

得到數據：
08-18 17:28:31.087 32148-32148/ I/cyy1: freeBytes=190 MB
08-18 17:28:31.088 32148-32148/ I/cyy1: usedBytes=22.68 GB
08-18 17:28:31.088 32148-32148/ I/cyy1: id=private
08-18 17:28:31.088 32148-32148/ I/cyy1: freeBytes=9.90 MB
08-18 17:28:31.088 32148-32148 I/cyy1: usedBytes=22.84 GB
08-18 17:28:31.088 32148-32148/ I/cyy1: id=emulated

其中emulated　是external stroage的數據。而private 是data的數據
３　可以通過以下ｃｏｄｅ驗證：
File path = Environment.getExternalStorageDirectory();
StatFs stat = new StatFs(path.getPath());
long blockSize = stat.getBlockSizeLong();
long blockCount = stat.getBlockCountLong();
long availableBlocks = stat.getAvailableBlocksLong();
long avaibByte =   stat.getAvailableBytes();
Log.i("cyy","avaibByte="+Formatter.formatFileSize(context,avaibByte));
long free= stat.getFreeBytes();
Log.i("cyy","free="+Formatter.formatFileSize(context,free));

String totalSize = Formatter.formatFileSize(context, blockCount*blockSize);
String availableSize = Formatter.formatFileSize(context, availableBlocks*blockSize);

Environment.getExternalStorageDirectory()　跟emulated 數據一致；Environment.getDataDirectory()       
和private數據一致。

andorid　storage tatal and free