mybatis入门

mybatis官方文档:https://mybatis.org/mybatis-3/zh/getting-started.html

1.新建项目，导入依赖

<!--mybatis依赖-->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.4.6</version>
</dependency>
<!--mysql依赖-->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.16</version>
</dependency>

2.创建mybatis-config.xml配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<!--configuration核心配置文件-->
<configuration>
    <!--environments 可以配置多个环境，default选择默认的环境-->
    <environments default="development">
        <!--id为development的环境-->
        <environment id="development">
            <!--事务管理-->
            <transactionManager type="JDBC"/>
            <!--数据源信息-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    
     <!--每一个mapper.xml都需要在mybatis核心配置文件中注册-->
    <mappers>
        <mapper resource="mapper/EmployeeMapper.xml"/>
    </mappers>
</configuration>

3.编写mybatis工具类

package com.aaa.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;

/**
 * User: Aurora
 * Date: 2020/4/26
 * Time: 23:57
 */
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static{
        try {
            //使用mybatis第一步：获取sqlSessionFactory对象
            String resource = "config/mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //sqlSession 完全包含了面向数据库执行sql命令所需的所有方法
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

4.编写实体类

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Employee {
    private Integer emp_id;
    private String emp_name;
    private String emp_address;
    private Integer emp_age;
}

5.编写mapper接口

public interface EmployeeMapper {
    List<Employee> selectAll();
}

6.创建mapper映射文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<!--namespace 对应一个mapper接口-->
<mapper namespace="com.licha.mapper.EmployeeMapper">

    <!--接口实现类转变为了一个mapper配置文件-->
    <select id="selectAll" resultType="com.licha.model.Employee">
    select * from employee
  </select>
</mapper>

7.测试

public class Test01 {
    public static void main(String[] args) {
       //第一步：获取session对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        //方式一：getMapper
        EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
        List<Employee> employees = mapper.selectAll();

        for (Employee e : employees) {
            System.out.println(e);
        }

        //关闭session
        sqlSession.close();
    }
}

mybatis入门

原文：https://www.cnblogs.com/licha233/p/12822412.html