Mybatis基本实例详解

Mybatis是一款开源的持久化框架，它可以将数据库的操作和Java代码解耦，大大简化了数据访问层的开发。本文将介绍Mybatis基本实例，包含如下内容：

• Mybatis简介
• Mybatis基本配置
• Mybatis增删改查示例1
• Mybatis增删改查示例2

Mybatis简介

Mybatis是一款优秀的持久层框架，它为Java开发提供了一个优秀的数据访问解决方案。Mybatis通过XML或注解的方式配置SQL映射，从而将Java对象与数据库表进行映射，实现了轻量级的数据访问层框架。

Mybatis基本配置

Mybatis基本配置主要包括配置数据源、配置SqlSessionFactory和SqlSessionFactoryBean，以及配置Mapper文件路径等。下面给出一个基本的Mybatis配置文件示例：

<!--配置数据源-->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/test"/>
    <property name="username" value="root"/>
    <property name="password" value="root"/>
</bean>

<!--配置SqlSessionFactory-->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="typeAliasesPackage" value="com.example.entity"/>
    <property name="mapperLocations">
        <array>
            <value>classpath:mapper/*.xml</value>
        </array>
    </property>
</bean>

<!--配置Mapper扫描-->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.example.mapper"/>
</bean>

配置完成后，我们就可以开始编写Mapper接口和Mapper.xml文件了。

Mybatis增删改查示例1

下面给出一个基本的Mybatis增删改查示例：

Mapper接口

public interface UserMapper {

    void insert(User user);

    void deleteById(Long id);

    void update(User user);

    User selectById(Long id);
}

Mapper.xml文件

<mapper namespace="com.example.mapper.UserMapper">
    <insert id="insert" parameterType="com.example.entity.User">
        insert into user (id, name, age) values (#{id}, #{name}, #{age})
    </insert>

    <delete id="deleteById" parameterType="java.lang.Long">
        delete from user where id = #{id}
    </delete>

    <update id="update" parameterType="com.example.entity.User">
        update user set name=#{name}, age=#{age} where id=#{id}
    </update>

    <select id="selectById" parameterType="java.lang.Long" resultType="com.example.entity.User">
        select id, name, age from user where id = #{id}
    </select>
</mapper>

测试代码

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserMapperTest {

    @Autowired
    private UserMapper userMapper;

    @Test
    public void testInsert() {
        User user = new User();
        user.setId(1L);
        user.setName("test");
        user.setAge(20);
        userMapper.insert(user);
    }

    @Test
    public void testDeleteById() {
        userMapper.deleteById(1L);
    }

    @Test
    public void testUpdate() {
        User user = new User();
        user.setId(1L);
        user.setName("test2");
        user.setAge(22);
        userMapper.update(user);
    }

    @Test
    public void testQueryById() {
        User user = userMapper.selectById(1L);
        System.out.println(user);
    }
}

Mybatis增删改查示例2

下面给出一个基本的Mybatis增删改查示例：

Mapper接口

public interface ArticleMapper {

    void insert(Article article);

    void deleteById(Long id);

    void update(Article article);

    Article selectById(Long id);

    List<Article> selectAll();
}

Mapper.xml文件

<mapper namespace="com.example.mapper.ArticleMapper">
    <insert id="insert" parameterType="com.example.entity.Article">
        insert into article (id, title, content) values (#{id}, #{title}, #{content})
    </insert>

    <delete id="deleteById" parameterType="java.lang.Long">
        delete from article where id = #{id}
    </delete>

    <update id="update" parameterType="com.example.entity.Article">
        update article set title=#{title}, content=#{content} where id=#{id}
    </update>

    <select id="selectById" parameterType="java.lang.Long" resultType="com.example.entity.Article">
        select id, title, content from article where id = #{id}
    </select>

    <select id="selectAll" resultType="com.example.entity.Article">
        select id, title, content from article
    </select>

</mapper>

测试代码

@RunWith(SpringRunner.class)
@SpringBootTest
public class ArticleMapperTest {

    @Autowired
    private ArticleMapper articleMapper;

    @Test
    public void testInsert() {
        Article article = new Article();
        article.setId(1L);
        article.setTitle("test");
        article.setContent("test content");
        articleMapper.insert(article);
    }

    @Test
    public void testDeleteById() {
        articleMapper.deleteById(1L);
    }

    @Test
    public void testUpdate() {
        Article article = new Article();
        article.setId(1L);
        article.setTitle("test2");
        article.setContent("test2 content");
        articleMapper.update(article);
    }

    @Test
    public void testQueryById() {
        Article article = articleMapper.selectById(1L);
        System.out.println(article);
    }

    @Test
    public void testQueryAll() {
        List<Article> articles = articleMapper.selectAll();
        System.out.println(articles);
    }
}

以上两个示例展示了基本的增删改查操作，通过配置Mapper接口和Mapper.xml文件，以及进行简单的测试，可以让我们更好地了解Mybatis的基本使用。