sm(spring+mybatis)注释版的整合

1.导入所需的包
2.mybatis配置文档与spring整合
（1）数据源的配置：

变成：

@Configuration  //beans
@ComponentScan("mybatis")  //component
@EnableTransactionManagement  //事务  
@PropertySource("db.properties")  //引入properties文件
@MapperScan("mybatis.mapper")   //扫描具体xml UserMapper.xml
//工厂配置
@Bean
    public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource) {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        factoryBean.setConfigLocation(new ClassPathResource("mybatis-config.xml"));
        factoryBean.setDataSource(dataSource);
        return factoryBean;
    }
    //数据源
    @Bean                       // 依赖Environment
    public DataSource dataSource(Environment env) {
        DriverManagerDataSource ds = new DriverManagerDataSource();
        // env.getProperty("someKey") 获得属性值
        ds.setDriverClassName(env.getProperty("jdbc.driverClassName"));
        ds.setUrl(env.getProperty("jdbc.url"));
        ds.setUsername(env.getProperty("jdbc.username"));
        ds.setPassword(env.getProperty("jdbc.password"));
        return ds;
    }

3.具体配置文件：

"mybatis.mapper.BlogMapper">

    -- one2one -->
    id="findByID" resultMap="blogid">
        select b.id blog_id,a.id author_id,b.title blog_title,a.name author_name 
        from author a inner join blog b 
        on a.id = b.id 
        where b.id = #{id}
    

    "Blog" id="blogid">
        <id property="id" column="blog_id"/>
        <result property="title" column="blog_title"/>
        -- 链接另外一张表（一对一） -->
        property="author" javaType="Author">
            <id property="id" column="author_id"/>
            <result property="name" column="author_name"/>
        
    

    -- one2many -->

    id="findByID2" resultMap="blogid2">
        select b.id blog_id,b.title blog_title,
          a.id author_id,a.name author_name ,
          p.subject post_subject,p.id post_id
        from author a inner join blog b 
        on b.id = a.blog_id 
        left join post p
        on b.id = p.blog_id
        where b.id = #{id}
    

    "Blog" id="blogid2">
        <id property="id" column="blog_id"/>
        <result property="title" column="blog_title"/>
        property="author" javaType="Author">
            <id property="id" column="author_id"/>
            <result property="name" column="author_name"/>
        
        -- collection（ofType）一对多  类型也不同余association（javaType） -->
        property="postlist" ofType="Post">
            <id property="id" column="post_id"/>
            <result property="subject" column="post_subject"/>
        
    


    id="findByID3" resultMap="blogid3">
        select b.id blog_id,b.title blog_title,
          a.id author_id,a.name author_name ,
          p.subject post_subject,p.id post_id,
          c.id comment_id,c.content comment_content
        from author a inner join blog b 
        on b.id = a.blog_id 
        left join post p
        on b.id = p.blog_id
        left join comment c
        on c.post_id = p.id
        where b.id = #{id}
    

    "Blog" id="blogid3">
        <id property="id" column="blog_id"/>
        <result property="title" column="blog_title"/>
        -- 
            <id property="id" column="author_id"/>
            <result property="name" column="author_name"/>
         -->
        property="author" resultMap="authorResult">

        property="postlist" ofType="Post">
            <id property="id" column="post_id"/>
            <result property="subject" column="post_subject"/>

            property="commentlist" ofType="Comment">
            <id property="id" column="comment_id"/>
            <result property="content" column="comment_content"/>
            

        

    

    -- 对于相同的链接另外一张表  可进行抽取， 但是限制了别名格式  列如：column="author_id"  column="author_name" -->
    "Author" id="authorResult">
        <id property="id" column="author_id" />     
        <result property="name" column="author_name"/>  
    

4.BlogMapper —>dao 没有具体的实现类，只有接口，具体实现都写在BlogMapper.xml中的具体sql语句了，执行方法被Mybatis封装了

public interface BlogMapper {
    //one2one
    Blog findByID(Long id);
    //one2many
    Blog findByID2(Long id);
    Blog findByID3(Long id);
}

5.关于带参数的crud，mybatis只接受一个参数，基本类型一个，类类型，map类型。当多个参数时，应该用代码封装成集合，或者注释@Param

相比于xml整合的简单很多。还是推荐xml,熟悉了解各个部分的作用，注释来的简单，容易忘记