mybatis 最佳實戰
阿新 • • 發佈：2020-07-16
mybatis 最佳實戰
目錄
1. mybatis 使用步驟
-
環境搭建，依賴匯入，配置檔案
-
mybatis generater 生成檔案
-
修改實體類（不可刪除，但是可以新增）
-
dao 層新增mapper 多表連線查詢的方法；
-
Xml 檔案配置SQL 語句，新增對映實體類
2. 依賴匯入
<dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.1.3</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency>
3. 配置檔案
spring: datasource: url: jdbc:mysql://49.233.186.242:3389/shop?useUnicode=true&characterEncoding=utf-8&useSSL=false username: root password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver mybatis: mapper-locations: classpath:generator/*.xml logging: level: com.yangtao.demo: debug
4. 一對多對映檔案 （對映裡面有引用類）
<resultMap id="BaseResultMap4" type="com.yangtao.demo.model.TbOrder"> <id column="id" jdbcType="INTEGER" property="id" /> <result column="CODE" jdbcType="VARCHAR" property="code" /> <result column="total" jdbcType="DOUBLE" property="total" /> <result column="user_id" jdbcType="INTEGER" property="userId" /> <association property="tbUser" javaType="com.yangtao.demo.model.TbUser"> <id column="id" jdbcType="INTEGER" property="id" /> <result column="username" jdbcType="VARCHAR" property="username" /> <result column="loginname" jdbcType="VARCHAR" property="loginname" /> <result column="PASSWORD" jdbcType="VARCHAR" property="password" /> <result column="phone" jdbcType="VARCHAR" property="phone" /> <result column="address" jdbcType="VARCHAR" property="address" /> </association> </resultMap>
<select id="selectCodeByUid" parameterType="java.lang.Integer" resultMap="BaseResultMap2">
select o.CODE,o.total from tb_user u,tb_order o
where u.id=o.user_id and u.id=#{uid}
</select>
5. 一對多對映檔案 （對映裡面有列表型別）
<resultMap id="BaseResultMap3" type="com.yangtao.demo.dto.CodeTestDto">
<result column="CODE" jdbcType="VARCHAR" property="code" />
<result column="total" jdbcType="DOUBLE" property="total" />
<collection property="codeTestDto" javaType="ArrayList"
column="id" ofType="com.yangtao.demo.dto.CodeTestDto" select="com.yangtao.demo.dao.TbOrderDao.selectCodeByUidAndReturnList"
fetchType="lazy">
<result column="CODE" property="code" />
<result column="total" property="total"/>
</collection>
</resultMap>
6. CRUD 標籤
<select id="selectCodeByUidAndReturnList2" parameterType="java.lang.Integer" resultMap="BaseResultMap4">
select * from tb_user u,tb_order o
where u.id=o.user_id and u.id=#{uid}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
delete from tb_order
where id = #{id,jdbcType=INTEGER}
</delete>
<insert id="insert" keyColumn="id" keyProperty="id" parameterType="com.yangtao.demo.model.TbOrder" useGeneratedKeys="true">
insert into tb_order (CODE, total, user_id)
values (#{code,jdbcType=VARCHAR}, #{total,jdbcType=DOUBLE}, #{userId,jdbcType=INTEGER})
</insert>
<update id="updateByPrimaryKey" parameterType="com.yangtao.demo.model.TbOrder">
update tb_order
set CODE = #{code,jdbcType=VARCHAR},
total = #{total,jdbcType=DOUBLE},
user_id = #{userId,jdbcType=INTEGER}
where id = #{id,jdbcType=INTEGER}
</update>
7. 動態SQL
1.IF
<select id="getBlogByConditionDynamic" resultMap="oneToManyNested">
select t1.id blog_id, t1.title, t2.id post_id, t2.section
from blog t1 left outer join post t2 on t1.id = t2.blog_id
<where>
<if test="title != null and title !=''">
and t1.title like '%'||#{title}||'%'
</if>
<if test="section != null and section != ''">
and t2.section like '%'||#{section}||'%'
</if>
</where>
</select>
@Test
public void testGetBlogByConditionDynamic() throws Exception {
List<Blog> blogList = blogMapper.getBlogByConditionDynamic("", "section");
Assert.assertNotNull(blogList);
}
<select id="getBlogByTitleOrSection" resultMap="oneToManyNested">
select t1.id blog_id, t1.title, t2.id post_id, t2.section
from blog t1 left outer join post t2 on t1.id = t2.blog_id where 1=1
<choose>
<when test="title != null and title !=''">
and t1.title like '%'||#{title}||'%'
</when>
<when test="section != null and section != ''">
and t2.section like '%'||#{section}||'%'
</when>
<otherwise>
and t1.title is not null and t2.section is not null
</otherwise>
</choose>
</select>
3. trim
<select id="getBlogByConditionDynamicTrim" resultMap="oneToManyNested">
select t1.id blog_id, t1.title, t2.id post_id, t2.section
from blog t1 left outer join post t2 on t1.id = t2.blog_id
<trim prefix="where" prefixOverrides="and | or">
<if test="title != null and title !=''">
and t1.title like '%'||#{title}||'%'
</if>
<if test="section != null and section != ''">
and t2.section like '%'||#{section}||'%'
</if>
</trim>
</select>
4. set
<update id="updateBlogTitleSet" parameterType="blog">
update blog
<set>
<if test="title != null and title != ''">
title = #{title}
</if>
<if test="id != null and id != ''">
, id = #{id}
</if>
</set>
where id = #{id}
</update>
5. foreach
<select id="dynamicForeach2Test" resultType="Blog">
select * from t_blog where id in
<foreach collection="array" index="index" item="item" open="(" separator="," close=")">
#{item}
</foreach>
</select>
8. 引數傳遞
List<Blog> getBlogByConditionDynamic(@Param("title") String title, @Param("section") String section);