如何使用sendirect()方法将搜索查询从servlet传递到jsp [英] How to use sendirect() method to pass search query from servlet to jsp

问题描述

我正在尝试在servlet中进行搜索查询，并将其加载到jsp表的原始文件中.

I'm trying to do the search query in servlet and load it to jsp table's raw.

    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将加载到浏览器的搜索栏中.这是我的jsp查询.

Insertion is working fine. Also first record of the search also load in search bar of the browser. And this is my jsp query.

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

我认为问题出在参数传递中.我对jsp有点新颖.所以不知道所有语法.请帮我.

I think problem is in parameter passing. I'm little bit novel to jsp. So don't know all syntax. Please help me.

编辑1 我这样改变了jsp.

Edit 1 I changed jsp like this.

                <%
                    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>

也像这样的servlet

Also servlet like this

   rs = state.executeQuery(search_sql);

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

现在我在jsp中开始的行中有org.apache.jasper.JasperException.

Now I'm having org.apache.jasper.JasperException in the line where while start in jsp.

这是错误.

推荐答案

您正尝试使用表达式标签，其用法如下:

You are trying to use the expression tag which is used as follows:

<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servlet中，如下所示:

Save the resultset object session in your servlet like this:

    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

并在您的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();
 }
}

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