如何使用 sendirect() 方法将搜索查询从 servlet 传递到 jsp

Question

我正在尝试在 servlet 中进行搜索查询并将其加载到 jsp 表的原始数据中。

    Connection dbCon = null;
    PreparedStatement state = null;
    ResultSet rs = null;
    String insert_sql = "insert into item(name,unit_price) values(?,?)";
    String search_sql = "select * from item";
    try {
        String item_name = request.getParameter("item_name");
        String up = request.getParameter("unit_price");
        try {
            dbCon = DB.JDBC.getConnection();
            state = dbCon.prepareStatement(insert_sql);
            dbCon.setAutoCommit(false);

            state.setString(1, item_name);
            state.setString(2, up);
            state.executeUpdate();

            dbCon.commit();


            rs = state.executeQuery(search_sql);
            while (rs.next()) {
                String item_id = rs.getString("item_id");
                String name = rs.getString("name");
                String unit_price = rs.getString("unit_price");
                String qty = rs.getString("qty");
                try {
                    response.sendRedirect("index.jsp?item_id=" + item_id + "&name=" + name + "&unit_price=" + unit_price + "&qty" + qty);
                } catch (Exception e) {
                    e.printStackTrace();
                }


            }
            response.sendRedirect("index.jsp?msg=New Item added successfully");
        } catch (Exception e) {
            e.printStackTrace();
            dbCon.rollback();
            out.close();
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

插入工作正常。搜索的第一条记录也加载到浏览器的搜索栏中。这是我的jsp查询。

               <tr>
                    <td><% request.getParameter("item_id");%></td>
                    <td><% request.getParameter("name");%></td>
                    <td><% request.getParameter("unit_price");%></td>
                    <td><% request.getParameter("qty");%></td>
                </tr>

我认为问题在于参数传递。我对jsp有点新奇。所以不知道所有的语法。请帮我。

编辑 1 我像这样改变了jsp。

                <%
                    ResultSet rs = (ResultSet) session.getAttribute("rs");
                    while (rs.next()) {
                        String item_id = rs.getString("item_id");
                        String name = rs.getString("name");
                        String unit_price = rs.getString("unit_price");
                        String qty = rs.getString("qty");
                %>
                <tr>
                    <td><%=item_id%></td>
                    <td><%=name%></td>
                    <td><%=unit_price%></td>
                    <td><%=qty%></td>
                </tr>
                <%}%>
            </tbody>

还有像这样的servlet

   rs = state.executeQuery(search_sql);

                session.setAttribute("rs", rs);
                response.sendRedirect("index.jsp"); //redirect to jsp without any params 

现在我在 jsp 中启动时的行中有 org.apache.jasper.JasperException。

这是错误。

Answer 1

添加你的servlet

request.setAttribute("rs",rs);

RequestDispatcher rd=request.getRequestDispatcher("your url");  
rd.forward(request, response); 

在jsp页面上

ResultSet rs = (ResultSet)request.getAttribute("rs");

<%while (rs.next()) {
    String item_id = rs.get(0);
    String name = rs.get(1);
    String unit_price = rs.get(2);
    String qty = rs.get(3);
    %>
    <tr>
      <td><%=item_id%></td>
      <td><%=name%></td>
      <td><%=unit_price%></td>
      <td><%=qty%></td>
    </tr>

Answer 2

您正在尝试使用如下使用的表达式标签：

<td><%=request.getParameter("item_id")%></td>
<td><%=request.getParameter("name")%></td>
<td><%=request.getParameter("unit_price")%></td>
<td><%=request.getParameter("qty")%></td>

更新：

将结果集对象会话保存在您的 servlet 中，如下所示：

    HttpSession session = request.getSession();
    rs = state.executeQuery(search_sql);  //after executing the query just write these two lines instead of while loop
   HashMap<String, ArrayList<String>> hm = new HashMap<String, ArrayList<String>>(); //change here
ArrayList<String> ls=null; //change here
int i=0;
    while (rs.next()) {
                ls=new ArrayList<String>(); //change here
                ls.add(rs.getString("item_id"));
                ls.add(rs.getString("name"));
                ls.add(rs.getString("unit_price"));
                ls.add(rs.getString("qty"));
                hm.put("row"+(++i), ls);
            }
    session.setAttribute("hm",hm);
    response.sendRedirect("index.jsp"); //redirect to jsp without any params

在你的 jsp 上：

<%
HashMap hm=(HashMap)session.getAttribute("hm");
Set<String> keyset=hm.keySet();
Iterator itr = keyset.iterator();
while (itr.hasNext()) {
    String key = itr.next();
    ArrayList<String> ls = (ArrayList)hm.get(key); 
    String item_id = ls.get(0);
    String name = ls.get(1);
    String unit_price = ls.get(2);
    String qty = ls.get(3);
    %>
    <tr>
      <td><%=item_id%></td>
      <td><%=name%></td>
      <td><%=unit_price%></td>
      <td><%=qty%></td>
    </tr>
<%
    } catch (Exception e) {
        e.printStackTrace();
 }
}