最近一直都在学习java，发现目前java招聘中，mybatis出现的频率挺高的，可能是目前java开发中使用比较多的数据库orm框架。于是我准备研究下spring boot和mybatis的整合。
1.在pom.xml文件中添加下面的配置
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<dependencies>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-web</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-test</artifactid>
<scope>test</scope>
</dependency>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-jdbc</artifactid>
</dependency>
<dependency>
<groupid>mysql</groupid>
<artifactid>mysql-connector-java</artifactid>
<scope>runtime</scope>
</dependency>
<dependency>
<groupid>com.alibaba</groupid>
<artifactid>druid</artifactid>
<version>1.0.29</version>
</dependency>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-data-jpa</artifactid>
</dependency>
<!-- 这个是官方的mybatis依赖，这个你不加没法用噻 -->
<dependency>
<groupid>org.mybatis.spring.boot</groupid>
<artifactid>mybatis-spring-boot-starter</artifactid>
<version>1.3.2</version>
</dependency>
<!-- 这个是自动生成mapper等的依赖，必须得加-->
<dependency>
<groupid>org.mybatis.generator</groupid>
<artifactid>mybatis-generator</artifactid>
<version>1.3.5</version>
<type>pom</type>
</dependency>
<!--这个是自动生成mapper等的依赖，必须得加 https://mvnrepository.com/artifact/org.mybatis.generator/mybatis-generator-core -->
<dependency>
<groupid>org.mybatis.generator</groupid>
<artifactid>mybatis-generator-core</artifactid>
<version>1.3.5</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-maven-plugin</artifactid>
</plugin>
<plugin>
<groupid>org.mybatis.generator</groupid>
<artifactid>mybatis-generator-maven-plugin</artifactid>
<version>1.3.2</version>
<configuration>
<!--配置文件存放的地址-->
<!--<configurationfile>src/main/resources/mybatis-generator/generatorconfig.xml</configurationfile>-->
<verbose>true</verbose>
<overwrite>true</overwrite>
</configuration>
</plugin>
</plugins>
</build>
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2.在application.properties配置文件中进行数据库和mybatis扫描的配置
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spring.datasource.driver-class-name=com.mysql.jdbc.driver
spring.datasource.url=jdbc:mysql://localhost:3306/yddy?useunicode=true&characterencoding=utf-8&servertimezone=utc
spring.datasource.username=root
spring.datasource.password=123456
mybatis.config-locations=classpath:mybatis-config.xml
# mapper文件
mybatis.mapper-locations=classpath:mapper/*.xml #这里直接写*，对后面自定义sql，编写xxxext.xml有好处，自动扫描到这些文件，不用再改配置了
mybatis.type-aliases-package=com.dameiweb.learn.model
logging.level.com.dameiweb.learn.dao=debug
#mybatis.config = mybatis 配置文件名称
#mybatis.mapperlocations = mapper xml 文件地址
#mybatis.typealiasespackage = 实体类包路径
#mybatis.typehandlerspackage = type handlers 处理器包路径
#mybatis.check-config-location = 检查 mybatis 配置是否存在，一般命名为 mybatis-config.xml
#mybatis.executortype = 执行模式。默认是 simple
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3.mybatis的配置和自动生成mapper的配置
在resource目录下新建一个generatorconfig.xml和mybatis-config.xml。内容如下：
generatorconfig.xml内容
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<?xml version="1.0" encoding="utf-8"?>
<!doctype generatorconfiguration
public "-//mybatis.org//dtd mybatis generator configuration 1.0//en"
"http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorconfiguration>
<classpathentry location="c:\users\nick\.m2\repository/mysql/mysql-connector-java/5.1.46/mysql-connector-java-5.1.46.jar"/>
<context id="db2tables" targetruntime="mybatis3">
<commentgenerator>
<property name="suppressdate" value="true"/>
<property name="suppressallcomments" value="true"/>
</commentgenerator>
<!--数据库链接地址账号密码-->
<jdbcconnection driverclass="com.mysql.jdbc.driver" connectionurl="jdbc:mysql://localhost:3306/yddy?useunicode=true&characterencoding=utf-8&servertimezone=utc" userid="root" password="123456">
</jdbcconnection>
<javatyperesolver>
<property name="forcebigdecimals" value="false"/>
</javatyperesolver>
<!--生成model类存放位置-->
<javamodelgenerator targetpackage="com.dameiweb.learn.model" targetproject="src/main/java">
<property name="enablesubpackages" value="true"/>
<!-- 从数据库返回的值被清理前后的空格 -->
<property name="trimstrings" value="false"/>
</javamodelgenerator>
<!--生成映射文件存放位置-->
<sqlmapgenerator targetpackage="mapper" targetproject="src/main/resources">
<property name="enablesubpackages" value="true"/>
</sqlmapgenerator>
<!--生成dao类存放位置-->
<!-- 客户端代码，生成易于使用的针对model对象和xml配置文件 的代码
type="annotatedmapper",生成java model 和基于注解的mapper对象
type="mixedmapper",生成基于注解的java model 和相应的mapper对象
type="xmlmapper",生成sqlmap xml文件和独立的mapper接口
-->
<javaclientgenerator type="xmlmapper" targetpackage="com.dameiweb.learn.dao" targetproject="src/main/java">
<property name="enablesubpackages" value="true"/>
</javaclientgenerator>
</context>
</generatorconfiguration>
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mybatis-config.xml的内容：
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<?xml version="1.0" encoding="utf-8" ?>
<!doctype configuration public "-//mybatis.org//dtd config 3.0//en" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<setting name="callsettersonnulls" value="true"/>
<setting name="cacheenabled" value="true"/>
<setting name="lazyloadingenabled" value="true"/>
<setting name="aggressivelazyloading" value="true"/>
<setting name="multipleresultsetsenabled" value="true"/>
<setting name="usecolumnlabel" value="true"/>
<setting name="usegeneratedkeys" value="false"/>
<setting name="automappingbehavior" value="partial"/>
<setting name="defaultexecutortype" value="simple"/>
<setting name="mapunderscoretocamelcase" value="true"/>
<setting name="localcachescope" value="session"/>
<setting name="jdbctypefornull" value="null"/>
</settings>
<typealiases>
<typealias alias="integer" type="java.lang.integer" />
<typealias alias="long" type="java.lang.long" />
<typealias alias="hashmap" type="java.util.hashmap" />
<typealias alias="linkedhashmap" type="java.util.linkedhashmap" />
<typealias alias="arraylist" type="java.util.arraylist" />
<typealias alias="linkedlist" type="java.util.linkedlist" />
</typealiases>
</configuration>
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这样我们就配置好了spring boot和mybatis与mybatis自动生成mapper和实体的功能。这样我们要生成某个表的实体和mapper的时候，只需要在generatorconfig.xml中javaclientgenerator标签之后添加下面的内容即可。
此处我们已yd_movies表为例(主要数据库表名字不要用复数，这个表名肯定是我之前脑子抽了，搞个复数的名字)
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<!--生成对应表及类名-->
<table tablename="yd_movies" domainobjectname="movie" enablecountbyexample="false" enableupdatebyexample="false"
enabledeletebyexample="false" enableselectbyexample="false" selectbyexamplequeryid="false">
<columnoverride column="cover_photos" javatype="java.lang.string" jdbctype="varchar" />
<columnoverride column="cover_photos_loc" javatype="java.lang.string" jdbctype="varchar" />
<columnoverride column="pubdates" javatype="java.lang.string" jdbctype="varchar" />
<columnoverride column="photographs_origin" javatype="java.lang.string" jdbctype="varchar" />
<columnoverride column="photographs_origin_loc" javatype="java.lang.string" jdbctype="varchar" />
<columnoverride column="languages" javatype="java.lang.string" jdbctype="varchar" />
<columnoverride column="awards" javatype="java.lang.string" jdbctype="varchar" />
<columnoverride column="summary" javatype="java.lang.string" jdbctype="varchar" />
</table>
<!--columnoverride使用这个标签是为了防止数据库字段类型为text时候，mybatis会生成xxxxwithblobs文件。-->
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然后点击idea右侧maven projects，就可以看到mybatis-generate下的mybatis-generate：generate，双击mybatis-generate：generate即可。
**generator 注意点，也可以说是bug
就是在生成的时候，在第二次生成的时候，dao 和entity 都会直接覆盖，而mapper.xml 会直接追加，导致运行报错，而且很难找。**
4.mybatis自定义sql
当我们需要自定义sql的时候，我们不能把这些也放到mapper文件中。不然，当数据库表的字段有更新需要重新生成mapper的时候，这样我们自定义的sql不就被覆盖没了么！所以我们需要在moviemapper.xml的同级目录里，新建一个moviemapperext.xml文件，把自定义的sql放到这里，例子如下：
moviemapperext.xml文件内容
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<?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="com.dameiweb.learn.dao.moviemapper" >
<select id="selectbycondition" resultmap="baseresultmap" parametertype="com.dameiweb.learn.dto.movierequest">
select yd_movies.* from yd_movies
left join yd_r_movie_countries on yd_movies.id = yd_r_movie_countries.movie_id
left join yd_countries cou on yd_r_movie_countries.country_id = cou.id
left join yd_r_movie_category on yd_movies.id = yd_r_movie_category.movie_id
left join yd_category cat on yd_r_movie_category.category_id = cat.id
left join yd_r_movie_actor on yd_movies.id = yd_r_movie_actor.movie_id
left join yd_actors a on yd_r_movie_actor.actor_id = a.id
where
yd_movies.status = 1
<if test="movierequest.title != null">
and yd_movies.title like "%"#{movierequest.title}"%"
</if>
<if test="movierequest.country != null">
and cou.id = #{movierequest.country}
</if>
<if test="movierequest.category != null">
and cat.id = #{movierequest.category}
</if>
<if test="movierequest.year != null">
and year = #{movierequest.year}
</if>
<if test="movierequest.rate != null">
and rate >= #{movierequest.rate}
</if>
<if test="movierequest.rate != null">
and rate < (#{movierequest.rate}+1)
</if>
<if test="movierequest.subtype != null">
and yd_movies.subtype = #{movierequest.subtype}
</if>
group by yd_movies.id
order by updated_at desc, year
</select>
</mapper>
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总结
以上所述是小编给大家介绍的spring boot整合mybatis并自动生成mapper和实体，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！
原文链接：https://www.ydstudio.net/archives/54.html