mybatis介绍
mybatis不会对应用程序或者数据库的现有设计强加任何影响。 sql写在xml里，便于统一管理和优化。通过sql语句可以满足操作数据库的所有需求。
mybatis结构
操作步骤
编写数据库对于的实体类entity
@Getter
@Setter
@ToString
public class User {
private Integer id;
private String name;
private String position;
private LocalDateTime create_time;
private LocalDateTime modify_time;
private Integer status;
}
<dependencies>
<!-- junit5坐标-->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>5.8.2</version>
<scope>test</scope>
</dependency>
<!-- mysql坐标-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
<!-- 快速构建get set toString方法-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.24</version>
</dependency>
<!-- mybatis坐标 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.9</version>
</dependency>
</dependencies>
编写mybatis核心配置文件sqlMapConfig.xml
具体内容参考mybatis官网：https://mybatis.org/mybatis-3/zh/getting-started.html
<?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>
<environments default="dev">
<!-- environment：环境 可配置多套环境 -->
<environment id="dev">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/testdb2?characterEncoding=UTF-8&useUnicode=true&useSSL=false&serverTimezone=GMT"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
<environment id="test">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/testdb2?characterEncoding=UTF-8&useUnicode=true&useSSL=false&serverTimezone=GMT"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<mappers>
<!-- 可配置多套数据来源 -->
<mapper resource="UserMapper.xml"/>
<mapper resource="UserMapper2.xml"/>
</mappers>
</configuration>
编写实体类映射文件UserMapper.xml
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace：命名空间
id：sql语句的id sql唯一标识user.findAll
resultType: 对于的实体类全路径
-->
<mapper namespace="user">
<select id="findAll" resultType="com.wn.entity.User">
select * from user
</select>
<select id="findOne" parameterType="int" resultType="com.wn.entity.User">
select * from user where id=#{id}
</select>
<insert id="addData" parameterType="com.wn.entity.User">
insert into user(name,position,create_time,modify_time)
values(#{name},#{position},#{create_time},#{modify_time})
</insert>
<update id="updateData" parameterType="com.wn.entity.User">
update user set position=#{position} where name=#{name}
</update>
<delete id="deleteData" parameterType="String">
delete from user where name=#{String}
</delete>
</mapper>
编写操作类
package com.wn.entity;
import jdk.internal.util.xml.impl.Input;
import lombok.val;
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 org.junit.jupiter.api.Test;
import java.io.IOException;
import java.io.InputStream;
import java.time.LocalDateTime;
import java.util.List;
class UserTest {
@Test
void selectTest() throws IOException {
//加载核心配置文件
InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
//获取sqlSessionFactory工厂对象
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
//获取sqlSession会话
SqlSession sqlSession = sqlSessionFactory.openSession();
//执行查询全部数据sql
// List<User> userList = sqlSession.selectList("user.findAll");
// List<User> userList = sqlSession.selectList("user2.findOne");
//执行条件查询sql
List<User> userList = sqlSession.selectList("user.findOne", 1);
//打印
userList.forEach(System.out::println);
//关闭sqlSession会话
sqlSession.close();
}
@Test
void insertTest() throws IOException {
InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
//插入数据
User user = new User();
user.setName("测试插入");
user.setPosition("测试");
user.setCreate_time(LocalDateTime.now());
user.setModify_time(LocalDateTime.now());
int insertUser = sqlSession.insert("user.addData",user);
sqlSession.commit();
System.out.println(insertUser);
sqlSession.close();
}
@Test
void updateTest() throws IOException {
InputStream inputStream=Resources.getResourceAsStream("sqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
//更新数据
User user=new User();
user.setName("老张");
user.setPosition("财务");
int updateUser = sqlSession.update("user.updateData", user);
sqlSession.commit();
System.out.println(updateUser);
sqlSession.close();
}
@Test
void deleteTest() throws IOException {
InputStream inputStream=Resources.getResourceAsStream("sqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
//指定name用户名删除数据
int deleteUser = sqlSession.update("user.deleteData", "测试插入");
sqlSession.commit();
System.out.println(deleteUser);
sqlSession.close();
}
}