案例-用户登录-代码实现

 代码实现

package com.itheima.mapper;

import com.itheima.pojo.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

public interface UserMapper {

    @Select("select * from tb_user where username = #{username} and password =#{password}")
    User select(@Param("username") String username,@Param("password") String password);
}

package com.itheima.pojo;

public class User {

    private Integer id;
    private String username;
    private String password;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

package com.itheima.web;

import com.itheima.mapper.UserMapper;
import com.itheima.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.接收用户名和密码
        String username=request.getParameter("username");
        String password=request.getParameter("password");

        //2.调用MyBatis完成查询
        //2.1 获取SqlSessionFactory对象
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.2 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //2.3 获取Mapper
        UserMapper UserMapper = sqlSession.getMapper(UserMapper.class);

        //2.4 调用方法
        User user = UserMapper.select(username, password);

        //2.5 释放资源
        sqlSession.close();

        //获取字符输出流writer，并设置content type
        response.setContentType("text/html;charset=utf-8");
        PrintWriter writer = response.getWriter();
        //3.判断user是否为null
        if (user != null){
            //登录成功   使用write方法返回出字符
            writer.write("登陆成功");
        }else {
            //登录失败   使用write方法返回出字符
            writer.write("登录失败");
        }


    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }

}