各位大牛 刚开始学Mybatis 我怎么看见有的人配置 resultMap里用实体类 有的人用java.util.HashMap 配置有啥诀窍啊

[hadoop333]

各位大牛 刚开始学Mybatis 我怎么看见有的人配置 resultMap里用实体类 有的人用java.util.HashMap 配置有啥诀窍啊
在<select 标签里 有的人配置resultType="java.util.HashMap"
有的人配置 resultMap 我都搞糊涂了 谁能给我讲讲吗 有统一的标准吗

[YangSy_001]

ResultType 一般表示返回的是某个字段，代表这个字段的类型，ResultMap 一般返回的是实体 就是是你前面定义的<ResultMap>这个映射的ID

[程序袁_哈哈]

ResultType可以是一个对象，或一个字段。 在返回一个list<user>时，你只要在ResultType中写下xxx.xxxx.user就可以。。。 ResultMap 一般多表联查时的返回结果，因为用一个对象无法装结果了，所以就用Map，这个map你可以在当前的xml中配制，也可以用util包下的map。

[hadoop333]

引用 4 楼 u010880076 的回复:

ResultType可以是一个对象，或一个字段。 在返回一个list<user>时，你只要在ResultType中写下xxx.xxxx.user就可以。。。 ResultMap 一般多表联查时的返回结果，因为用一个对象无法装结果了，所以就用Map，这个map你可以在当前的xml中配制，也可以用util包下的map。

好的 我自己找点资料看看 thanks

[奄灬苟且偷生]

以下为个人理解 你说的两种方式一种是配置好实体类、那得建立在简单的SQL语句 如select * from table hashmap就不用考虑返回的数据对应的类了 比如下方的SQL语句我就用hashmap、其实是我比较懒、勿喷 select B.id as blog_id, B.title as blog_title, B.author_id as blog_author_id, A.id as author_id, A.username as author_username, A.password as author_password, A.email as author_email, A.bio as author_bio, A.favourite_section as author_favourite_section, P.id as post_id, P.blog_id as post_blog_id, P.author_id as post_author_id, P.created_on as post_created_on, P.section as post_section, P.subject as post_subject, P.draft as draft, P.body as post_body, C.id as comment_id, C.post_id as comment_post_id, C.name as comment_name, C.comment as comment_text, T.id as tag_id, T.name as tag_name from Blog B left outer join Author A on B.author_id = A.id left outer join Post P on B.id = P.blog_id left outer join Comment C on P.id = C.post_id left outer join Post_Tag PT on PT.post_id = P.id left outer join Tag T on PT.tag_id = T.id where B.id = #{id}

[奄灬苟且偷生]

以下为个人理解 你说的两种方式一种是配置好实体类、那得建立在简单的SQL语句 如select * from table hashmap就不用考虑返回的数据对应的类了 比如下方的SQL语句我就用hashmap、其实是我比较懒、勿喷 select B.id as blog_id, B.title as blog_title, B.author_id as blog_author_id, A.id as author_id, A.username as author_username, A.password as author_password, A.email as author_email, A.bio as author_bio, A.favourite_section as author_favourite_section, P.id as post_id, P.blog_id as post_blog_id, P.author_id as post_author_id, P.created_on as post_created_on, P.section as post_section, P.subject as post_subject, P.draft as draft, P.body as post_body, C.id as comment_id, C.post_id as comment_post_id, C.name as comment_name, C.comment as comment_text, T.id as tag_id, T.name as tag_name from Blog B left outer join Author A on B.author_id = A.id left outer join Post P on B.id = P.blog_id left outer join Comment C on P.id = C.post_id left outer join Post_Tag PT on PT.post_id = P.id left outer join Tag T on PT.tag_id = T.id where B.id = #{id}

[Joyce-Luo]

resultType只是指定当前的返回类型，当然就看你需要什么样的类型了，不过一般以对象居多，因为重用性就会增强

[Laughing_Lz]

引用 2 楼 ch1240249252 的回复:

以下为个人理解 你说的两种方式一种是配置好实体类、那得建立在简单的SQL语句 如select * from table hashmap就不用考虑返回的数据对应的类了 比如下方的SQL语句我就用hashmap、其实是我比较懒、勿喷 select B.id as blog_id, B.title as blog_title, B.author_id as blog_author_id, A.id as author_id, A.username as author_username, A.password as author_password, A.email as author_email, A.bio as author_bio, A.favourite_section as author_favourite_section, P.id as post_id, P.blog_id as post_blog_id, P.author_id as post_author_id, P.created_on as post_created_on, P.section as post_section, P.subject as post_subject, P.draft as draft, P.body as post_body, C.id as comment_id, C.post_id as comment_post_id, C.name as comment_name, C.comment as comment_text, T.id as tag_id, T.name as tag_name from Blog B left outer join Author A on B.author_id = A.id left outer join Post P on B.id = P.blog_id left outer join Comment C on P.id = C.post_id left outer join Post_Tag PT on PT.post_id = P.id left outer join Tag T on PT.tag_id = T.id where B.id = #{id}

这个你selectList怎么写 返回List<HashMap<String,?>>， ?处该写什么呀？泛型吗？求指教