Mybatis入门（二）Mybatis入门案例（Maven – mybatis原生）

文章目录

一、导入依赖

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.tedu</groupId>
    <artifactId>mybatis_demo01</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <!--MySQL-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.26</version>
        </dependency>

        <!--MyBatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>

        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>

        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
</project>

二、编写User实体类

User

@Data
@Accessors(chain = true)
public class User implements Serializable {
    private Integer id;
    private String name;
    private Integer age;
    private String sex;
}

三、编写持久层UserMapper接口

UserMapper

public interface UserMapper {
    List<User> getAllUser();   
}

四、编写UserMapper映射文件

UserMapper.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.cy.mapper.UserMapper">
    <select id="getAllUser" resultType="cn.cy.pojo.User">
        select * from demo_user
    </select>
</mapper>

四、编写mybatis-config.xml配置文件

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?> <!-- xml声明-->
<!-- 约束 规定了根标签为 configuration 和 约束文件 xxx.dtd -->
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!-- 根标签 -->
<configuration>
    <!--设置连接数据库的环境-->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/demo_admin?serverTimezone=UTC&amp;rewriteBatchedStatements=true&amp;characterEncoding=utf-8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <!--引入映射文件-->
    <mappers>
        <mapper resource="mappers/UserMapper.xml"/>
    </mappers>
</configuration>

四、编写jdbc.properties 修改优化mybatis-config.xml配置文件

jdbc.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/demo_admin?useSSL=false&useUnicode=true&characterEncoding=UTF-8
jdbc.username=root
jdbc.password=root

mybatis-config.xml

<?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>
    <!--引入外部配置,进行动态替换-->
    <properties resource="jdbc.properties"></properties>
    <!--设置连接数据库的环境-->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <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>
    <!--引入映射文件-->
    <mappers>
        <mapper resource="mappers/UserMapper.xml"/>
    </mappers>
</configuration>

六、编写UserMapperTests测试类

UserMapperTests

public class UserMapperTests {

    @Test
    public void testGetAllUser() throws IOException {
        /*创建SqlSessionFactory*/
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        /*从SqlSessionFactory中获取sqlSession*/
        SqlSession sqlSession = sqlSessionFactory.openSession();
        /*获取mapper接口,执行接口方法*/
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        List<User> userList = userMapper.getAllUser();
        // [User(id=1, name=zs, age=18, sex=男), User(id=2, name=ls, age=20, sex=男), User(id=3, name=xiaohong, age=18, sex=女)]
        System.out.println(userList);
        sqlSession.close();
    }
}

七、demo_user数据库表模板

八、mybatis入门案例总结

1. mybatis入门案例步骤：

导入依赖
- MySQL
- Mybatis
- Juint
- lombok
编写实体类，实体类属性需要与数据库表字段一一对应
编写Mapper接口，添加接口方法
编写Mapper映射文件
编写mybatis-config.xml配置文件
- 配置数据源信息
- 配置映射关系
测试类测试
- 读取配置文件，创建SqlSessionFactory工厂对象
- 获取SqlSession会话对象，开启数据库连接
- 获取持久层接口实现类
- 调用方法，获取返回值结果
- 关闭SqlSession链接