Mybatis 03 封装工具类方法和使用

缘由

由于类中的部分代码重复量过多,而且一般不进行改变,这时可以设计一个工具类进行 调用即可, 可简化代码和提高效率

如 Mybatis 02 中的如下代码重复率很大

String resource = "config.xml";
        Reader reader = Resources.getResourceAsReader(resource);
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession = factory.openSession();

创建工具类

package com.dhl.beyond.util;

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 java.io.IOException;
import java.io.Reader;

public class MybatisUtil {

    public static SqlSession getSqlSession() throws IOException {
        String resource = "config.xml";
        Reader reader = Resources.getResourceAsReader(resource);
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession = factory.openSession();
        return sqlSession;
    }

}

工具类引用如下

如查询表中所有内容

@Test
    public void selectAllUser() throws IOException {
        SqlSession session =  MybatisUtil.getSqlSession();
        List<Object> list = session.selectList("com.dhl.beyond.shiyan3.userMapper.selectAllUsers");
        System.out.println(list);
    }

Mapper文件如下

 <select id="selectAllUsers" resultType="com.dhl.beyond.shiyan1.User">
        select * from users
    </select>

结果集