使用mybatis查询

配置文件

在mybatis配置文件中，需要配置数据源、mapper文件路径、类型别名等信息。

<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
    </mappers>
    <typeAliases>
        <typeAlias type="com.example.mybatisdemo.User" alias="User"/>
    </typeAliases>
</configuration>

Mapper文件

在Mapper文件中定义SQL语句和参数映射。

<mapper namespace="com.example.mybatisdemo.UserMapper">
    <select id="getUserById" resultType="User">
        select * from user where id = #{id}
    </select>
</mapper>

Java代码

使用SqlSession进行查询操作。

public class UserDao {
    private static SqlSessionFactory sqlSessionFactory;

    static {
        String resource = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }

    public User getUserById(int id) {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        User user = sqlSession.selectOne("com.example.mybatisdemo.UserMapper.getUserById", id);
        sqlSession.close();
        return user;
    }
}

以上是使用mybatis进行查询的基本步骤，具体操作可以根据业务需求进行调整。