如何判断SD卡是否已满

private boolean isSDCardFull() {
        File path = Environment.getExternalStorageDirectory();
        StatFs statFs = new StatFs(path.getPath());
        long blockSize = statFs.getBlockSize();
        long totalBlocks = statFs.getBlockCount();
        long availableBlocks = statFs.getAvailableBlocks();
        if (availableBlocks * blockSize == 0) {
            return true;
        }
        return false;
    }