对比 MyBatis，你看出什么端倪？

V2EX = way to explore

V2EX 是一个关于分享和探索的地方

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这是一个创建于 1777 天前的主题，其中的信息可能已经有所发展或是发生改变。

项目地址： https://github.com/braisdom/ObjectiveSql

1 简单查询

@DomainModel
public class Blog {
    private Long id;
    private String title;
    private Integer state;
    @Relation(relationType = RelationType.BELONGS_TO)
    private Author author;
}

根据单字段查询

MyBatis

ObjectiveSQL

public interface BlogMapper {
  @Select("SELECT * FROM blog WHERE id = #{id}")
  Blog selectBlog(int id);
}
...
BlogMapper mapper = session.getMapper(BlogMapper.class); 
Blog blog = mapper.selectBlog(i);

Blog blog = Blog.queryByPrimaryKey(1);

稍微复杂一点的查询

MyBatis

ObjectiveSQL

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.mybatis.example.BlogMapper">
  <select id="findByTitle" resultType="Blog">
    select * from Blog where title like  '%#{title}%'
  </select>
</mapper>
...
BlogMapper mapper = session.getMapper(BlogMapper.class); 
Blog blog = mapper.findByTitle("标题");

public static Blog queryByTitle(String title) {
     Query<Blog> query = createQuery();
     query.where("title like ?",  "%" + title + "%");
     return query.queryFirst();
}
...
Blog blog = Blog.queryByTitle(1);

2 复杂查询

动态查询

MyBatis

ObjectiveSQL

<select id="findActiveBlogLike"
     resultType="Blog">
  SELECT * FROM BLOG
  WHERE
  <if test="state != null">
    state > #{state}
  </if>
  <if test="title != null">
    AND title like #{title}
  </if>
  <if test="author != null and author.name != null">
    AND author_name like #{author.name}
  </if>
</select>
...
BlogMapper mapper = session.getMapper(BlogMapper.class); 
Blog blog = mapper.findActiveBlogLike(...);

Blog.Table blog = Blog.asTable();
Select select = new Select();
LogicalExpression eternalExpression = new EternalExpression();
if(state != null)
     eternalExpression = eternalExpression.and(blog.state > state);
if(title != null)
     eternalExpression = eternalExpression.and(blog.title.like(title));
if(author != null && author.name != null)
     eternalExpression = eternalExpression.and(blog.author.like(author.name));
return select.from(blog).where(eternalExpression).execute();

关联查询

MyBatis

ObjectiveSQL

<mapper>
  <resultMap type="Blog" id="blog">
    <id column="id" property="id" />
    ...
    <association property="author" javaType="Author">
      ...
    </association>
  </resultMap>
  <select id="findBlog" parameterType="int" resultMap="blog">
    ...
  </select>
</mapper>
...
BlogMapper mapper = session.getMapper(BlogMapper.class); 
Blog blog = mapper. findBlog(...);

Blog blog = Blog.queryByPrimaryKey(1, 
                    Blog.BELONGS_TO_AUTHOR)

103 条回复 • 2020-12-14 14:47:03 +08:00

1 2

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101

Braisdom

2020-12-14 12:40:58 +08:00

join, sub query 这些都是传统 ORM 框架的弱势，有兴趣去这里，https://github.com/braisdom/ObjectiveSql
话题太长，这里讨论不方便

102

liuhuan475

2020-12-14 14:32:38 +08:00

@Braisdom 为什么要用你这个框架而不用 mybatis-plus

103

Braisdom

2020-12-14 14:47:03 +08:00

@liuhuan475 这个问题很好，是我后续要出更多文档进行比较的方向，至于为什么我目前先介绍几点：

1 ）动态代码生成：对于简单查询我只需要一个模型定义就可以，而 MyBatis 则需要一个多余的 Mapper 。
2 ）复杂表达式（算术，比较，逻辑）：我可能直接将 Java 的表达式转换成 SQL 表达式，例如：aTable.column + bTable.column...，而 MyBatis 只能通过字符串。
3 ）关联查询，分页查询：我只需要一个 Annotation，而 MyBatis 则需要 Mapper + XML

上面只是简单的描述，这些是我针对 MyBatis 的弱点进行的挑战。

1 2

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