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Spring Boot整合mybatis并自動生成mapper和實體實例解析

2024-07-14 08:40:43
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最近一直都在學習Java,發現目前Java招聘中,mybatis出現的頻率挺高的,可能是目前Java開發中使用比較多的數據庫ORM框架。于是我準備研究下Spring Boot和mybatis的整合。

1.在pom.xml文件中添加下面的配置

<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> <!-- 這個是官方的mybatis依賴,這個你不加沒法用噻 -->  <dependency>   <groupId>org.mybatis.spring.boot</groupId>   <artifactId>mybatis-spring-boot-starter</artifactId>   <version>1.3.2</version>  </dependency>  <!-- 這個是自動生成mapper等的依賴,必須得加-->  <dependency>   <groupId>org.mybatis.generator</groupId>   <artifactId>mybatis-generator</artifactId>   <version>1.3.5</version>   <type>pom</type>  </dependency>  <!--這個是自動生成mapper等的依賴,必須得加 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>

2.在application.properties配置文件中進行數據庫和mybatis掃描的配置

spring.datasource.driver-class-name=com.mysql.jdbc.Driverspring.datasource.url=jdbc:mysql://localhost:3306/yddy?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTCspring.datasource.username=rootspring.datasource.password=123456mybatis.config-locations=classpath:mybatis-config.xml# mapper文件mybatis.mapper-locations=classpath:mapper/*.xml #這里直接寫*,對后面自定義sql,編寫xxxExt.xml有好處,自動掃描到這些文件,不用再改配置了mybatis.type-aliases-package=com.dameiweb.learn.modellogging.level.com.dameiweb.learn.dao=debug#mybatis.config = mybatis 配置文件名稱#mybatis.mapperLocations = mapper xml 文件地址#mybatis.typeAliasesPackage = 實體類包路徑#mybatis.typeHandlersPackage = type handlers 處理器包路徑#mybatis.check-config-location = 檢查 mybatis 配置是否存在,一般命名為 mybatis-config.xml#mybatis.executorType = 執行模式。默認是 SIMPLE

3.mybatis的配置和自動生成mapper的配置

在resource目錄下新建一個generatorConfig.xml和mybatis-config.xml。內容如下:

generatorConfig.xml內容

<?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>  <!--數據庫鏈接地址賬號密碼-->  <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類存放位置-->  <javaModelGenerator targetPackage="com.dameiweb.learn.model" targetProject="src/main/java">   <property name="enableSubPackages" value="true"/>   <!-- 從數據庫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類存放位置-->  <!-- 客戶端代碼,生成易于使用的針對Model對象和XML配置文件 的代碼    type="ANNOTATEDMAPPER",生成Java Model 和基于注解的Mapper對象    type="MIXEDMAPPER",生成基于注解的Java Model 和相應的Mapper對象    type="XMLMAPPER",生成SQLMap XML文件和獨立的Mapper接口  -->  <javaClientGenerator type="XMLMAPPER" targetPackage="com.dameiweb.learn.dao" targetProject="src/main/java">   <property name="enableSubPackages" value="true"/>  </javaClientGenerator> </context></generatorConfiguration>

mybatis-config.xml的內容:

<?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>

這樣我們就配置好了Spring Boot和mybatis與mybatis自動生成mapper和實體的功能。這樣我們要生成某個表的實體和mapper的時候,只需要在generatorConfig.xml中javaClientGenerator標簽之后添加下面的內容即可。

此處我們已yd_movies表為例(主要數據庫表名字不要用復數,這個表名肯定是我之前腦子抽了,搞個復數的名字)

<!--生成對應表及類名-->  <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使用這個標簽是為了防止數據庫字段類型為text時候,mybatis會生成xxxxWithBLOBs文件。-->

然后點擊idea右側Maven projects,就可以看到mybatis-generate下的mybatis-generate:generate,雙擊mybatis-generate:generate即可。

**generator 注意點,也可以說是BUG

就是在生成的時候,在第二次生成的時候,dao 和entity 都會直接覆蓋,而Mapper.xml 會直接追加,導致運行報錯,而且很難找。**

4.mybatis自定義sql

當我們需要自定義sql的時候,我們不能把這些也放到mapper文件中。不然,當數據庫表的字段有更新需要重新生成mapper的時候,這樣我們自定義的sql不就被覆蓋沒了么!所以我們需要在MovieMapper.xml的同級目錄里,新建一個MovieMapperExt.xml文件,把自定義的sql放到這里,例子如下:

MovieMapperExt.xml文件內容

<?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>

總結

以上所述是小編給大家介紹的Spring Boot整合mybatis并自動生成mapper和實體,希望對大家有所幫助,如果大家有任何疑問請給我留言,小編會及時回復大家的。在此也非常感謝大家對VeVb武林網網站的支持!


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