目录

mybatis注解开发

Qzai 收录于 Mybatis

2022-11-07 约 532 字预计阅读 2 分钟

目录

一、常用注解

@Insert
@Update
@Delete
@Select
@Result 实现结果集封装
@Results 可以与@Result一起使用，封装多个结果集
@One 实现一对一结果集封装
@Many 实现一对多结果集封装

二、简单增删改查

        
    @Insert("insert into user (username) values (#{username})")
    public void add(User user);

    @Update("update user set username = #{username} where id = #{id}")
    public void update(User user);

    @Delete("delete from user where id = #{id}")
    public void delete(Integer id);

    @Select("select * from user")
    public List<User> select();

    @Select("select * from user where id = #{id}")
    public User findById(Integer id);

三、实现复杂映射

@Results 代替的标签是 <resultMap>,可以使用单个@Result,或@Result集合：@Results({@Result(), @Result(), ...}) 或 @Results({@Result()})
@Result 代替了<id>和<result>标签
- column: 数据库列名
- property: 装配的属性名
- one: 需要使用@One注解(@Result(one=@One)())
- many: 需要使用@Many注解(@Result(many=@Many)())
@One 代替了<assocation>标签
@Many 代替了<collection>标签

1.一对一

        
        
        
    
    /**
     * @One里可以写sql，也可以引用方法
     */
    @Results({
        @Result(property = "id", column = "id"),
        @Result(property = "orderTime", column = "orderTime"),
        @Result(property = "total", column = "total"),
        @Result(property = "user", column = "uid", javaType = User.class,
            one = @One(select = "com.example.demo.mapper.AnnoUserMapper.findById"))
    })
    @Select("select * from orders")
    public List<Order> findOrderAndUser();

2.一对多

        
        
        
    
    @Select("select * from user")
    @Results({
        @Result(property = "id", column = "id"),
        @Result(property = "username", column = "username"),
        @Result(property = "orderList", column = "id", javaType = List.class,
            many = @Many(select = "com.example.demo.mapper.AnnoOrderMapper.findOrderByUid"))
    })
    public List<User> findAll();

3.多对多

类似一对多

示例代码见：https://gitee.com/ixinglan/mybatis-tec.git