将 var 从 javascript 传递给 servlet

Question

我是 webdev 的新手，我有一个问题。 我不知道如何将 javascript var 从 jsp 传递到 servlet。 这是我的带有 javascript 代码的 jsp：

<form action="http://localhost:8080/PerryBet/EventoServlet" method="post">
    <input type="hidden" id ="deleteForm" name="action" value="delete">
    <table  class="table">
    <thead class="thead-dark">
        <tr>
            <th scope="col">Palinsesto</th>
            <th scope="col">Evento</th>
            <th scope="col">Campionato</th>
            <th scope="col">Data</th>
            <th scope="col">Squadra Casa</th>
            <th scope="col">Squadra Casa</th>
            <th scope="col"> 1 </th>
            <th scope="col"> X </th>
            <th scope="col"> 2 </th>
            <th scope ="col"> Modifica </th>
            <th scope ="col"> Elimina </th> 
        </tr>
    </thead>

        <%
        EventoModel model = new EventoModel();
        Collection<EventoBean> eventi = new ArrayList<EventoBean>();

        eventi = model.doRetrieveAll();

        if(eventi != null & eventi.size() > 0) {
            Iterator<?> it = eventi.iterator();
            while (it.hasNext()) {
                EventoBean bean = (EventoBean)it.next();

                %>
            <tbody>
                <tr>

                    <td><%= bean.getEvento()  %></td>
                    <td><%= bean.getPalinsesto() %></td>
                    <td><%= bean.getCampionato()%></td>
                    <td><%= bean.getData()%></td>
                    <td><%= bean.getSquadraCasa() %></td>
                    <td><%= bean.getSquadraTrasferta() %></td>
                    <td><%= bean.getQuota1()%></td>
                    <td><%= bean.getQuotaX()%></td>
                    <td><%= bean.getQuota2() %></td>
                    <td><button type="submit" >Elimina</button></td>

                </tr>
            </tbody>
            <% 
            }

        }

        %>
        </table>
    </form>

    <script type="text/javascript">
        $('button').click(function () {
            // Get the first td
            var codEvento = $(this).closest('tr').children('td:eq(1)').text();

            alert('Codice Evento:  ' + codEvento);



        });
        </script>

小服务程序：

package controller;

import java.io.IOException;
import java.sql.Date;
import java.sql.SQLException;
import java.text.ParseException;
import java.text.SimpleDateFormat;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import bean.EventoBean;
import model.EventoModel;

/**
 * Servlet implementation class EventoServlet
 */
@WebServlet("/EventoServlet")
public class EventoServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
EventoModel model = new EventoModel();

/**
 * @see HttpServlet#HttpServlet()
 */
public EventoServlet() {
    super();
    // TODO Auto-generated constructor stub
}

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String action = request.getParameter("action");

    EventoBean bean = new EventoBean();

    try {   
        if(action != null) {
            if(action.equalsIgnoreCase("delete")) {
                System.out.println("test");
                String cod = (String)request.getParameter("codEvento");
                System.out.println(cod);


                //model.eliminaEvento(evento);
                System.out.println("deleted");
            }
        } else {


    bean.setPalinsesto((String)request.getParameter("palinsesto"));
    bean.setEvento((String)request.getParameter("evento"));
    bean.setCampionato((String)request.getParameter("campionato"));
    bean.setData(setData(request));
    bean.setSquadraCasa((String)request.getParameter("squadraCasa"));
    bean.setSquadraTrasferta((String)request.getParameter("squadraTrasferta"));
    bean.setQuota1((String) request.getParameter("quota1"));
    bean.setQuotaX((String) request.getParameter("quotaX"));
    bean.setQuota2((String) request.getParameter("quota2"));



        model.aggiungiEvento(bean);
        request.getRequestDispatcher("Eventi.jsp").forward(request, response);
        }
    } catch (SQLException e){
        e.printStackTrace();
    }





}

/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    doGet(request, response);
}

public  Date setData(HttpServletRequest request)  {
    String startDateStr = request.getParameter("data");
    SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
    java.util.Date parsed = null;
    try {
        parsed = sdf.parse(startDateStr);
    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    Date sqlDate = new Date(parsed.getTime());
    return sqlDate;


}

}

现在我想将 var codEvento 传递给 servlet，我该怎么做？ 是否有一些像 setAttribute 或类似的方法？ 我尝试使用 ajax，但我完全不知道它是如何工作的以及我应该如何使用它。

Answer 1

在jsp中使用input<type="hidden" id ="codEvento" name="codEvento"/>并在你的javascript代码中设置这个值

<script type="text/javascript">
    $('button').click(function () {
        // Get the first td
        var codEvento = $(this).closest('tr').children('td:eq(1)').text();
        document.getElementById("codEvento").value= codEvento
        alert('Codice Evento:  ' + codEvento);
    });
    </script>

然后在servlet中，你可以得到这个值：

String codEvento = request.getParameter("codEvento");