MyBatis注解位于org.apache.ibatis.annotations包下，常用注解如下
1 select 映射查询sql语句 2 insert 映射插入语句 3 update 映射更新语句 4 delete 映射删除语句 5 result 在列和属性之间的单独结果映射，属性包括id column one many，等 id是一个布尔值，表示是否用于主键映射，one是单独的联系和xml中<association>相似 ，mang对集合而言，和xml中的<collection>相似 4 results 多个结果映射（result）列表 。 5 optins提供配置选项的附加值，在映射语句上作为附加功能配置出现。6 当映射方法需要多个参数时，应用于映射器方法参数来给每个参数娶一个名字，否则多参数将会以他们的顺序位置和SQL语句的表达式进行映射
注解使用 @select @insert @update @delete 可以完成常见的增删改查功能sql语句映射
public interface AUserMapper { @Insert("INSERT INTO USER(username,sex, birthday, address) VALUES(#{username},#{sex},#{birthday},#{address})") @Options(useGeneratedKeys=true, keyProperty="id") int saveUser(User user); @Delete("delete from user where id=#{id}") int removeUser(@Param("id") Integer id); @Update("update user set username=#{username}, birthday=#{birthday}, sex=#{sex}, address=#{address} where id=#{id}") void modifyUser(User user); @Select("select * from user where id=#{id}") @Results({ @Result(id=true, column="id", property="id"), @Result(column="username", property="username"), @Result(column="birthday", property="birthday"), @Result(column="sex", property="sex"), @Result(column="address", property="address"), }) User selectUserById(Integer id); @Select("select * from user") List<User> selectAllUser(); } @Test public void saveUserTest() throws Exception{ //读取配置文件 //全局配置文件的路径 String resource = "SqlMapConfig.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); //创建SqlSessionFactory SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); //创建SqlSession SqlSession sqlSession = sqlSessionFactory.openSession(); //调用SqlSession的增删改查方法 //第一个参数：表示statement的唯一标示 AUserMapper mapper = sqlSession.getMapper(AUserMapper.class); User user = new User(); user.setUsername("whe"); user.setSex("i"); user.setAddress("ds"); mapper.saveUser(user); System.out.println(user.getId()); sqlSession.close(); }
一对一 一个订单只有一个用户
public interface UserMapper { @Select("select * from user where id=#{id}") User selectUserById(Integer id); } public interface OrderMapper { @Select("select * from orders where id=#{id}") @Results({ @Result(id=true, column="id", property="id"), @Result(column="number", property="number"), @Result(column="createtime", property="createtime"), @Result(column="note", property="note"), @Result(column="user_id", property="user", one =@One(select="com.itheima.ms.mapper.UserMapper.selectUserById", fetchType=FetchType.EAGER)) }) Orders selectOrdersById(Integer id); }
MyBatis 注解支持动态SQL ， @selectprovider @insertprovider @updateprovider @deleteprovider 来帮助构建动态sql语句，org.apache.ibatis.jdbc.SQL用来拼接sql语句，Privoder方方法可接收ava对象，map对象
@SelectProvider(type=com.itheima.ms.mapper.UserSqlPrivoder.class, method="selectWithPar") List <User> selectUserById(Map<String, Object> map);
public class UserSqlPrivoder { public String selectWithPar(final Map<String, Object> map){ return new SQL(){ { SELECT("*"); FROM("user"); if (map.get("id") != null){ WHERE(" id=#{id}"); } } }.toString(); } }