工具类里面一般是静态方法，通过把读取mybatis主配置文件获取SqlSession的一些列繁琐步骤封装成工具类，减少代码量。

Mybatis工具类

src/main/java/com/oxygen/utils/MybatisUtil.java

package com.oxygen.utils;

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.InputStream;

public class MybatisUtil {

    private static SqlSessionFactory sqlSessionFactory=null;
    static {
        String config="MybatisConfig.xml";
        try {
            InputStream  in = Resources.getResourceAsStream(config);
           sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

    }

    public static SqlSession getSqlSession() {
        SqlSession session = null;
        if(sqlSessionFactory!=null){
            session=sqlSessionFactory.openSession(true);
        }
        return session;
    }
}