模糊查询查不到东西怎么办？

package Servlet;

import java.io.IOException;
import java.io.PrintWriter;
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 bean.Message;

@SuppressWarnings({ "serial", "unused" })
public class ListServlet extends HttpServlet {

	private static  String url = "jdbc:MYSQL://127.0.0.1:3306/micro_message";
	private static  String user = "root";
	private static  String password = "123456";

	/**
	 * Constructor of the object.
	 */
	public ListServlet() {
		super();
	}

	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		try {
			Class.forName("com.mysql.jdbc.Driver");
			Connection conn = null;
			try {
				 request.setCharacterEncoding("utf-8");
				 response.setCharacterEncoding("utf-8");
				 String command=request.getParameter("command");
				 String description=request.getParameter("description");
				 request.setAttribute("command", command);
				 request.setAttribute("description", description);
				 conn = DriverManager.getConnection(url,user,password);
				 StringBuilder sql=new StringBuilder("select * from message where 1=1");
				 List<String> paramList=new ArrayList<String>();
				 if(command!=null&&!"".equals(command.trim())){
					 sql.append(" and command='"+command+"' ");
					 paramList.add(command);
				 }
				 if(description!=null&&!"".equals(description.trim())){
					 sql.append(" and DESCRIPTION like '%' ? '%'");
					 paramList.add(description);
				 }
				 PreparedStatement statement=conn.prepareStatement(sql.toString());
				 for(int i = 1;i<paramList.size();i++){
					 statement.setString(i, paramList.get(i));
				 }
				 ResultSet rs=statement.executeQuery(sql.toString());
				 List<Message> messageList=new ArrayList<Message>();
				 while(rs.next()){
					 Message message=new Message();
					 message.setId(rs.getInt("id"));
					 message.setCommand(rs.getString("command"));
					 message.setContent(rs.getString("content"));
					 message.setDescription(rs.getString("description"));
					 messageList.add(message);
				 }
				 request.setAttribute("messageList", messageList);
			} catch (SQLException e) {
				e.printStackTrace();
			}
			} catch (ClassNotFoundException e) {
				e.printStackTrace();
		}
		request.getRequestDispatcher("/WEB-INF/jsp/back/List.jsp").forward(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doGet(request, response);
	}

	public void init() throws ServletException {
		// Put your code here
	}

}

报错是 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '? '%'' at line 1