MyBatis

Posted by Bruce Tsai
03/10/2016

• MyBatis

透過 XML 與 Mapper 來處理 SQL query

MyBatis 是一個 Java 持久化框架，為 iBATIS 3.0（retired） 的分支版本，它通過 XML 描述符或註解把物件與儲存過程或 SQL 語句關聯起來。同時也支援與 Spring 的整合。

以 XML 與 Mapper 進行查詢

<?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="selectBlog" resultType="Blog">
    select * from Blog where id = #{id}
  </select>
</mapper>

Blog blog = session.selectOne("org.mybatis.example.BlogMapper.selectBlog", 101);

在 XML 中以使用邏輯條件組合查詢

• Dynamic SQL

<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>
  </where>
</select>

以介面設定 annotation 進行查詢

public interface BlogMapper {
  @Select("SELECT * FROM blog WHERE id = #{id}")
  Blog selectBlog(int id);
}

SqlSession session = sqlSessionFactory.openSession();
try {
  BlogMapper mapper = session.getMapper(BlogMapper.class);
  Blog blog = mapper.selectBlog(id);
  // do work
} finally {
  session.close();
}