结果集配置

User selectUserById(int id);

<!--用于实体类属性和表中字段不一致时-->
<resultMap type="user" id="userMap">
        <id column="id" property="id"/>
        <result column="age" property="age"/>
        <result column="user_name" property="userName"/>
        <result column="sex" property="sex"/>
        <result column="birthday" property="birthday"/>
</resultMap>

<select id="selectUserById" parameterType="java.lang.Integer" resultMap="userMap" >
        select * from t_user where id = #{id}
</select>

映射注解

@SelectProvider(value = BlogMapperProvide.class, method = "getPage")
List<Blog> getPage(@Param("title")String title, @Param("page")int page, @Param("size")int size);
/**
 * 复杂sql语句的构建器 
 * 方式一：内部类
 */
class BlogMapperProvider {
	
	public static String getPage(@Param("title")String title, @Param("page")int page, @Param("size")int size) {
		return new SQL() {{
			SELECT("*");
			FROM("blog");
			if(title != null) {
				WHERE("title like concat(‘%‘, #{title} , ‘%‘)");
			}
			if(page > 0 && size > 0) {
				LIMIT("#{page}, #{size}");
			}
		}}.toString();
	}
}

/**
 * 方式二：外部公开的类
 */
public class BlogMapperProvide {

	public String getPage(@Param("title")String title, @Param("page")int page, @Param("size")int size) {
		return new SQL() {{
			SELECT("*");
			FROM("blog");
			if(title != null) {
				WHERE("title like concat(‘%‘, #{title} , ‘%‘)");
			}
			if(page > 0 && size > 0) {
				LIMIT("#{page}, #{size}");
			}
		}}.toString();
	}

}

视图封装

• 在视图层vo文件夹下编写封装类

/**
 * 根据用户获取博客
 * @param bup   
 * BlogUserParam类型是视图层vo中封装的数据类型
 */
List<BlogUserVO> getUserBlog(BlogUserParam bup) throws MapperException;

<!--根据用户获取博客  传入的参数类型和返回的参数类型 为视图层封装的类型-->
<select id="getUserBlog"
	parameterType="top.yfly.blog.vo.BlogUserParam"
	resultType="top.yfly.blog.vo.BlogUserVO">
	select
	<include refid="selbu"></include>
	from t_blog b,
	t_user_info ui, t_user u
	where b.user_id = ui.user_id
	and
	b.user_id = u.id and ui.user_id = u.id
	and b.user_id = #{userId}
	<if test="blogType != null">
		and b.blog_type = #{blogType}
	</if>
	<if test="blogTitle != null">
		and b.blog_tile like concat(‘%‘,#{blogTitle} ,‘%‘)
	</if>
	<if test="inputTime != null">
		order by b.create_time
	</if>
	<if test="praisedCount != null">
		order by ui.praised_count desc
	</if>
	<if test="accessCount != null">
		order by ui.access_count desc
	</if>
	<if test="pageNum !=null and pageSize != null">
		limit #{pageNum}, #{pageSize}
	</if>
</select>

mybatis入门