求大神帮助解决小问题，一直无法调用到DAO层的login方法

package com.tnt.jsp;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.fasterxml.jackson.databind.ObjectMapper;

import entity.Users;
import Dao.UserDao;

/**

• Servlet implementation class LoginServlet
  */
  public class LoginJsonServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;

  /**

  • @see HttpServlet#HttpServlet() */ public LoginJsonServlet() { super(); // TODO Auto-generated constructor stub }

  /**

  • @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse

  •  response)
    

    */
    protected void doGet(HttpServletRequest request,
    HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("UTF-8");
    // response.setContentType("Textcml;charset=UTF-8");
    String uname = request.getParameter("uname");
    String upass = request.getParameter("upass");
    // PrintWriter pw = response.getWriter();

    Users condition = new Users();
    condition.setUname(uname);
    condition.setUpass(upass);

    UserDao userDao = new UserDao();
    Users user = userDao.login(condition)就是这里一直无法调用？？？？？？？？

    PrintWriter out = response.getWriter();
    if (user != null) {//生成json字符串2
    ObjectMapper mapper = new ObjectMapper();
    String json = mapper.writeValueAsString(user);
    out.write(json);
    out.flush();
    out.close();
    }

    // 得到session对象
    // 如果传false，当前session对象就返回session对象，如果不存在就返回新创建的对象
    HttpSession session = request.getSession();

    if (user != null) {
    session.setAttribute("USER", user);
    request.setAttribute("USERNAME", uname);
    //请求转发
    request.getRequestDispatcher("/success.jsp ").forward(request,response);
    // 重定向
    response.sendRedirect("success.html");
    request.getRequestDispatcher("/BloggersSearvlet").forward(request,
    response);
    System.out.println("login");

     response.sendRedirect("BloggersSearvlet");
    

    // pw.println(uname + "登陆成功！");
    } else {
    // pw.println(uname + "登录失败");
    request.getRequestDispatcher("/fail.jsp").forward(request,response);
    request.getRequestDispatcher("/fail.jsp")
    .forward(request, response);
    }

  }

  /**

  • @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
  • response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); doGet(request, response); }

}

DAO类
package Dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.concurrent.locks.Condition;

import org.apache.tomcat.jni.User;

import entity.Users;

public class UserDao {
public Users login(User condition)

{
    Connection connection = ConnectionManager.getConnection();
    Statement stmt = null;
    Users user = null;
    String sql = "select  userid,username,password from tbl_user where username='"
            + user.getUname()
            + "' and password ='"
            + user.getUpass()
            + "'";

    ResultSet rs = null;
    try {
        stmt = connection.createStatement();
        rs = stmt.executeQuery(sql);
        while (rs.next()) {
            user = new Users();
            int userid = rs.getInt("USERID");
            String uname = rs.getString("UNAME");
            String upass = rs.getString("UPASS");
            int age = rs.getInt("AGE");
            user.setUserid(userid);
            user.setUname(uname);
            user.setUpass(upass);
            user.setAge(age);

        }
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        ConnectionManager.closeResultSet(rs);
        ConnectionManager.closeStatement(stmt);
        ConnectionManager.closeConnection(connection);
    }
    return user;

}

}