查不出来QAQ。

Question

package com.lzh.servlet;

import java.io.IOException;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.lzh.bean.Message;

/**

 * 

 * 列表页面初始化设置

 *

 */

@SuppressWarnings("serial")

public class ListServlet extends HttpServlet{

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

try {

req.setCharacterEncoding("UTF-8");

String command = req.getParameter("command");

String description = req.getParameter("description");

req.setAttribute("command", command);

req.setAttribute("description", description);

Class.forName("com.mysql.jdbc.Driver");

Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/webee","root","123456");

StringBuilder sql =new StringBuilder( "select ID,COMMAND,DESCRIPTION,CONTENT from t_message where 1=1");

List<String> paramList = new ArrayList<String>();

if(command!= null&&!"".equals(command.trim())){

sql.append(" and COMMAND=? ");

}

if(description!= null&&!"".equals(description.trim())){

sql.append("and DESCRIPTION like '%' ? '%' ");

paramList.add(description);

}

PreparedStatement statement = conn.prepareStatement(sql.toString());

for(int i=0;i<paramList.size();i++){

statement.setString(i+1, paramList.get(i));

}

ResultSet rs =statement.executeQuery();

List<Message> messageList = new ArrayList<Message>();

while(rs.next()){

Message message = new Message();

messageList.add(message);

message.setId(rs.getString("ID"));

message.setCommand(rs.getString("COMMAND"));

message.setDescription(rs.getString("DESCRIPTION"));

message.setContent(rs.getString("CONTENT"));

}

req.setAttribute("messageList", messageList);

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

req.getRequestDispatcher("/WEB-INF/jsp/back/list.jsp").forward(req, resp);

}

@Override

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

this.doGet(req, resp);

}

}

控制台报这个错 No value specified for parameter 1