Adding Hibernate objects to MySQL concurrently

Question

I am Hibernate newbie, and developing a servlet which gets its parameters from a URL, creates a Hibernate object, then stores it into a MySQL database.

I am sending 1000 URLs concurrently. When I look at the MySQL table, it adds only the last object to the database.

doGet method:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    // TODO Auto-generated method stub

    //HttpSession session = request.getSession(true);
    //session.putValue("uid", count);

    String id = request.getParameter("id");
    String url = request.getParameter("url");
    String lastVisitTime = request.getParameter("lastVisitTime");
    String visitCount = request.getParameter("visitCount");
    String title = request.getParameter("title");
    String typedCount = request.getParameter("typedCount");

    HistoryItem hi = new HistoryItem(id, url, lastVisitTime, visitCount, title, typedCount);

    File f = new File("C:\\Users\\atılay\\Desktop\\apache-tomcat-7.0.30-windows-x64\\jspservlets\\UserModeling\\src\\hibernate.cfg.xml");

    SessionFactory sessionFactory = new Configuration().configure(f).buildSessionFactory();
    Session session = sessionFactory.openSession();
    session.beginTransaction();
    session.save(hi);
    session.getTransaction().commit();
    session.flush();
    session.close();

}

HistoryItem:

public class HistoryItem {

@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
@Basic(optional = false)
private int i;
private String id  = "";
private String url = "";
private String lastVisitTime = "";
private String visitCount = "";
private String title = "";
private String typedCount = "";
}

What is the problem? I could not find any solution.

Answer 1

If you're creating an object/entity to be saved into the database, you shouldn't be setting it's ID.

Allocating the ID happens when the object is saved -- and this is Hibernate's responsibility. Having the ID already set, means HB considers the object has been saved already.

Really this is not a very good question, or coding style, or example.

'Sending 1000 URL concurrently'. What does that mean? You have 1000 browsers open at once, and send a request from all of them simultaneously? Talk sense.

Your SessionFactory should be kept in the webapp or servlet. This code is doing an entire Hibernate startup & initialization, for every page request.

File f = new File("C:\\Users\\atılay\\Desktop\\apache-tomcat-7.0.30-windows-x64\\jspservlets\\UserModeling\\src\\hibernate.cfg.xml");

SessionFactory sessionFactory = new Configuration().configure(f).buildSessionFactory();

Get rid of 'ID' as a parameter -- or else use it optionally, to load & edit records -- and do the Hibernate setup properly.

Then your project might work.