检索插入到servlet对象中的最后一个id

Question

我正在为我的大学做评估，我的老师给了我一些初始代码以供复制，现在我陷入了自己的代码中。基本上，此代码创建一个新对象，以ID插入数据库。我需要捕获在对象中创建的交易ID，才能将其发送到下一页。查看交易（市场门户）。对不起我的英语，但是有点难。

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    request.setCharacterEncoding("UTF-8");
    int user_id = Integer.parseInt(request.getParameter("user_id"));
    int feed_id = Integer.parseInt(request.getParameter("feed_id"));
    Date now = new java.sql.Date(System.currentTimeMillis());
    //int transaction_done =0; MEANS NO TRANSACTION
    //int transaction_done =1; MEANS USER NTERESTED SEND APPLICATION TO REACH FEEDER 
    //int transaction_done =2; MEANS FEEDER DECLINE TRANSACTION
    //int transaction_done =3; MEANS TRANSACTION SUCCESSFULL, PROCEED WITH REVIEW
    int transaction_done =1;

    TransactionService objTransactionService = new TransactionService();        

    Transaction objTransaction = new Transaction(0, feed_id,user_id,now,transaction_done);

    if (objTransactionService.saveTransaction(objTransaction)) {
        HttpSession sesion=request.getSession();
        String done = "transaction in process! well done.";
        sesion.setAttribute("done", done);
        response.sendRedirect("chat.jsp?done=true");
    } else {
        HttpSession sesion=request.getSession();
        String done = "Error, try again.";
        sesion.setAttribute("done", done);
        response.sendRedirect("chat.jsp?done=false");
    }
}

希望你能帮助我。