SqlSessionFactory工具类

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SqlSessionFactory 工厂只创建一次，不需要重复创建。 代码优化：

//2.1获取SqlSessionFactory对象
String resouce = "mybatis.config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

解决了低码的重复。

🔥SqlSessionFactoryUtils

创建在com.jkj.utils包下：

package com.jkj.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class SqlSessionFactoryUtils { 
    private static SqlSessionFactory sqlSessionFactory;
    static{ 
        String resource = "mybatis.config.xml";
        InputStream inputStream = null;
        try { 
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) { 
            e.printStackTrace();
        }
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }

    public static SqlSessionFactory getSqlSessionFactory(){ 
        return sqlSessionFactory;
    }

}

🔥LoginServlet.java

package com.jkj.web;

import com.jkj.mapper.UserMapper;
import com.jkj.pojo.User;
import com.jkj.utils.SqlSessionFactoryUtils;
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;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet { 
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 
        //获取用户名和密码
        String username = req.getParameter("username");
        String password = req.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); */
        SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();
        //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，并设置content type
        resp.setContentType("text/html;charset=utf-8");

        //判断user是否为空
        if (user !=null){ 
            resp.getWriter().write("登录成功！");
        }
        else { 
            resp.getWriter().write("登录失败！");
        }

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 
       this.doGet(req, resp);
    }
}