Mybatis

Mybatis最简单的使用

目录结构

数据库

Sql语句

-- auto-generated definition
create table student
(
    id           bigint      not null
        primary key,
    password     varchar(20) null,
    class_number int         null
);

数据

Maven坐标

     <dependencies>
<!--        Mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.11</version>
        </dependency>
<!--        数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
<!--        工具类-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
        </dependency>
    </dependencies>

实体类(Entity)

package cn.pickle.entity;

import lombok.Data;

/**
 * @author Pickle
 * @version V1.0
 * @date13:53 2022/12/14
 */
@Data
public class Student {
    private Long id;
    private String password;
    private Integer classNumber;
}

测试类

package cn.pickle;

import cn.pickle.entity.Student;
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;

/**
 * @author Pickle
 * @version V1.0
 * @date 2022/12/15 10:06
 */
public class Test {
    public static void main(String[] args){

        try {
            String resources = "mybatis-config.xml";

            Reader reader = Resources.getResourceAsReader(resources);

            final SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);

            try(final SqlSession sqlSession = sqlSessionFactory.openSession()){
                final Student student = sqlSession.selectOne("selectStudent", 1);
                System.out.println("Student ID: " + student.getId());
                System.out.println("Student Password: " + student.getPassword());
                System.out.println("Student ClassNumber: " + student.getClassNumber());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

配置文件

config.properties

jdbc.password=root
jdbc.username=root
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis_demo

mybatis-config.xml

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

    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>

    <typeAliases>
        <package name="cn.pickle.entity"/>
    </typeAliases>

<!--    typeHandler-->

<!--    objectFactory-->

<!--    <plugins>-->
<!--        <plugin interceptor=""></plugin>-->
<!--    </plugins>-->

    <environments default="develop">
        <environment id="develop">
            <transactionManager type="JDBC">
                <!-- 跳过关闭连接自动提交 -->
                <property name="skipSetAutoCommitOnClose" value="true"/>
            </transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="StudentMapper.xml"/>
    </mappers>

</configuration>

StudentMapper.xml

<?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">


<mapper namespace="cn.pickle.entity.Student">
    <select id="selectStudent" resultType="student">
        Select * from mybatis_demo.student where id = #{id};
    </select>
</mapper>

测试结果