输入查询条件会报参数索引超出范围的错误
java.sql.SQLException: Parameter index out of range (1 > number of parameters, which is 0).
两个百分号之间加了空格，
控制台打印的paramerList为？？？？？？是不是表示页面的参数没有传过去？
package 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 bean.Message;
/**
* @author 570
*
*/
public class ListServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
try {
String command = req.getParameter("command");//从页面拿到参数
String description =req.getParameter("description");
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?characterEncoding=utf8&useSSL=true","root","root");
// String sql ="SELECT ID,COMMAND,DESCRIPTION,CONTENT FROM imooc_mybatis_list";
//where 1=1 用于语句拼接。。不明所以
StringBuilder sql = new StringBuilder("select ID,COMMAND,DESCRIPTION,CONTENT from imooc_mybatis_list where 1=1");
PreparedStatement ps = conn.prepareStatement(sql.toString());
// PreparedStatement ps = conn.prepareStatement(sql);
//多条件查询时，利用List做缓冲，保存查询参数，然后再循环赋值
List<String> paramerList = new ArrayList<String>();
//语句拼接如果查询的指令非空且非空字符串则执行语句拼接查询
if (command!=null&&!"".equals(command.trim())) {
sql.append(" and COMMAND=? ");
paramerList.add(command);
}
if (description!=null&&!"".equals(description.trim())) {
sql.append("and DESCRIPTION like '%' ? '%' ");
paramerList.add(description);
}
//把页面上的语句拿给要送到数据库查询的ps中
for (int i = 0; i < paramerList.size(); i++) {
System.out.println(paramerList.get(i));
ps.setString(i+1, paramerList.get(i));//错误指向这一行
}
ResultSet rs = ps.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) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
req.getRequestDispatcher("/WEB-INF/jsp/list.jsp").forward(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
