public static class SDCardInfo {
    public long total;

    public long free;
}

public static SDCardInfo getSDCardInfo() {
    String sDcString = android.os.Environment.getExternalStorageState();

    if (sDcString.equals(android.os.Environment.MEDIA_MOUNTED)) {
        File pathFile = android.os.Environment.getExternalStorageDirectory();

        try {
            android.os.StatFs statfs = new android.os.StatFs(pathFile.getPath());

            // 获取SDCard上BLOCK总数
            long nTotalBlocks = statfs.getBlockCount();

            // 获取SDCard上每个block的SIZE
            long nBlocSize = statfs.getBlockSize();

            // 获取可供程序使用的Block的数量
            long nAvailaBlock = statfs.getAvailableBlocks();

            // 获取剩下的所有Block的数量(包括预留的一般程序无法使用的块)
            long nFreeBlock = statfs.getFreeBlocks();

            SDCardInfo info = new SDCardInfo();
            // 计算SDCard 总容量大小MB
            info.total = nTotalBlocks * nBlocSize;

            // 计算 SDCard 剩余大小MB
            info.free = nAvailaBlock * nBlocSize;

            return info;
        } catch (IllegalArgumentException e) {
            Log.e(LOG_TAG, e.toString());
        }
    }

    return null;
}