Android：在同一文件上获取不同的文件大小

Question

我将数据库文件下载到Android存储。我很困惑为什么打开数据库后查询文件大小不同。下载后，它返回“大小”。打开后，它返回“磁盘大小”。

    //download database file to storage
     ...(the content length from server is 52224)

    //query size
    databaseFile = new File(DBGlassConfig.getDatabasePath());
    long sizeBeforeLoading = databaseFile.length(); // 52224

    //open database
    if (databaseHandler == null)
        databaseHandler = new DatabaseHandler(MainActivity.this);

    //query size
    databaseFile = new File(DBGlassConfig.getDatabasePath());
    long sizeAfterLoading = databaseFile.length(); // 53248


//open database
public DatabaseHandler(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
            this.context = context;
            db = 
SQLiteDatabase.openOrCreateDatabase(DBGlassConfig.getDatabasePath(), null);
            }