Mybatis 环境项目搭建

前言

• 好久没写mybatis 了，今天写条博客 加深一些mybatis的 印象！

步骤一：创建maven 工程 导入mybatis 相关依赖

        <!--单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
        <!--mysql 驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!--mybatis 包-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.10</version>
        </dependency>

步骤二：创建实体类

/**
 * @Classname User
 * @Description 用户实体类
 * @Date 2021/5/17 21:49
 * @Created by 闲言
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
     

    private int id;
    private String username;
    private String password;
    private String perms;

}

步骤三：创建Mapper 接口并添加方法

/**
 * @Classname UserMapper
 * @Description 用户mapper接口
 * @Date 2021/5/17 21:50
 * @Created by 闲言
 */

public interface UserMapper {
     

    List<User> findAll();
}

步骤四：创建mapper 文件

• 注意：在resources 资源目录下创建和mapper 接口一样的层级路径
• 非必须

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

    <select id="findAll" resultType="cn.bloghut.domain.User">
        select * from user;
    </select>
</mapper>

mapper接口包路径

mapper文件路径1

步骤五：编写mybatis 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>
    <!--配置别名-->
    <typeAliases>
        <package name="cn.bloghut.domain.User"/>
    </typeAliases>

    <environments default="dev">
        <environment id="dev">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
                <property name="username" value="xx"/>
                <property name="password" value="xx"/>
            </dataSource>
        </environment>
    </environments>

   <mappers>
       <!--指定mapper 文件的路径-->
       <mapper resource="cn/bloghut/mapper/UserMapper.xml"/>
   </mappers>

</configuration>

步骤六：测试

public class Test1 {
     

    @Test
    public void test1() throws Exception{
     
        //加载配置文件
        InputStream inputStream = Resources.getResourceAsStream("mybatis.xml");
        //获取SqlSessionFactoryBuilder
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        //通过SqlSession工厂
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
        //获取SQLSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //获取代理的mapper 接口
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        //调用方法，获取返回值
        List<User> users = mapper.findAll();
        for (User user : users) {
     
            System.out.println(user);
        }

    }
}