Spring 中使用 Mybatis generator 自动生成代码
Mybatis generator 是一个 Mybatis 插件，可以用于自动生成项目中需要的 pojo 类、对应的 Mapper 接口和 mapper.xml 文件。使用该插件，一方面可以节省开发时间，另一方面也避免手写时打错字的问题。
由于工作需要，我打算在原有的 Spring 项目中使用 Mybatis generator 自动生成代码，以便简化 DAO 层的开发。
闲言少叙，just do it！
1. 引入依赖
a. 父模块配置
<properties> <spring_version>4.3.9.RELEASE</spring_version> <mysql_connector_version>5.1.21</mysql_connector_version> <gson_version>2.2.2</gson_version> <commons_beanutils_version>1.8.3</commons_beanutils_version> <commons_io_version>2.0.1</commons_io_version> <junit_version>4.12</junit_version> <skip_maven_deploy>true</skip_maven_deploy> <lombok.version>1.18.2</lombok.version> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.build.sourceOptimize>true</project.build.sourceOptimize> <project.build.sourceDebug>true</project.build.sourceDebug> <project.build.sourceTarget>1.8</project.build.sourceTarget> </properties> <dependencyManagement> <dependencies> <!-- Spring libs --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-beans</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring_version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring_version}</version> <scope>test</scope> </dependency> <dependency> <groupId>commons-beanutils</groupId> <artifactId>commons-beanutils</artifactId> <version>${commons_beanutils_version}</version> </dependency> <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>${commons_io_version}</version> </dependency> <dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>${gson_version}</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>${mysql_connector_version}</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.2.8</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> <version>1.2.2</version> </dependency> <dependency> <groupId>org.apache.ibatis</groupId> <artifactId>ibatis-sqlmap</artifactId> <version>${ibatis_version}</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.0.12</version> </dependency> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjweaver</artifactId> <version>1.8.4</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit_version}</version> <scope>test</scope> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.58</version> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>${lombok.version}</version> <scope>provided</scope> </dependency> </dependencies> </dependencyManagement>
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b. 子模块配置
我们在子模块中引入插件 mybatis-generator-maven-plugin。
<dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.mybatis.generator</groupId> <artifactId>mybatis-generator-maven-plugin</artifactId> <version>1.3.5</version> <configuration> <configurationFile>${basedir}/src/main/resources/generatorConfig.xml</configurationFile> <overwrite>true</overwrite> <verbose>true</verbose> </configuration> <dependencies> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>${mysql_connector_version}</version> </dependency> </dependencies> </plugin> </plugins> </build>
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2. 引入配置文件
由于上文在 mybatis-generator-maven-plugin 插件中指定了所需的配置文件：generatorConfig.xml，所以在子模块 resources 目录下引入该配置文件。
<?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> <context id="baseset" targetRuntime="MyBatis3Simple" defaultModelType="flat"> <commentGenerator> <property name="suppressAllComments" value="false"/> <property name="suppressDate" value="true"/> </commentGenerator> <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://ip:port/db_name" userId="username" password="password"> </jdbcConnection> <!-- 指定生成 pojo 实体类、mybatis映射xml文件、mapper接口的具体位置 --> <javaModelGenerator targetPackage="cn.com.meta.pojo" targetProject="src/main/java"> <property name="enableSubPackages" value="true"/> <property name="trimStrings" value="true"/> </javaModelGenerator> <sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources"> <property name="enableSubPackages" value="true"/> </sqlMapGenerator> <javaClientGenerator targetPackage="cn.com.meta.mapper" targetProject="src/main/java" type="XMLMAPPER"> <property name="enableSubPackages" value="true"/> </javaClientGenerator> <!--可以配置多个 table--> <table tableName="t_table_name" domainObjectName="TableNamePojo" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"> <generatedKey column="id" sqlStatement="Mysql" identity="true"/> </table> </context> </generatorConfiguration>
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3. 自动生成 Mapper 接口、XML 文件和 pojo 类
点击 IDEA 右侧的 Maven 控件栏，找到对应模块下面的 mybatis-generator 插件，双击即可自动生成 Mapper 接口、mapper.xml 文件和 pojo 类。
4. Spring 中使用 Mapper 接口
a. 配置 spring-meta.xml 文件
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" xmlns="http://www.springframework.org/schema/beans" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd"> <!-- 使用annotation注解方式配置事务 --> <tx:annotation-driven transaction-manager="transactionManager"/> <!-- 使用JDBC事务 --> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean> <!-- 引入配置文件，测试时打开，集成时注释 --> <context:property-placeholder location="classpath:config.properties" ignore-unresolvable="true"/> <!--创建jdbc数据源 --> <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> <!-- 基本属性 url、user、password --> <property name="url" value="${jdbc.url}"/> <property name="username" value="${jdbc.username}"/> <property name="password" value="${jdbc.password}"/> <!--测试时打开，集成时注释--> <property name="driverClassName" value="${jdbc.driver}"/> <!-- 配置初始化大小、最小、最大 --> <property name="initialSize" value="10"/> <property name="minIdle" value="10"/> <property name="maxActive" value="200"/> <!-- 配置获取连接等待超时的时间 --> <property name="maxWait" value="60000"/> <!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 --> <property name="timeBetweenEvictionRunsMillis" value="60000"/> <!-- 配置一个连接在池中最小生存的时间，单位是毫秒 --> <property name="minEvictableIdleTimeMillis" value="300000"/> <property name="validationQuery" value="SELECT 'x'"/> <property name="testWhileIdle" value="true"/> <property name="testOnBorrow" value="false"/> <property name="testOnReturn" value="false"/> <!-- 打开PSCache，并且指定每个连接上PSCache的大小 --> <property name="poolPreparedStatements" value="true"/> <property name="maxPoolPreparedStatementPerConnectionSize" value="20"/> <!-- 配置监控统计拦截的filters，去掉后监控界面sql无法统计 --> <property name="filters" value="stat"/> </bean> <!-- 配置SqlSessionFactoryBean --> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"/> <!--Mybatis配置文件--> <!--<property name="configLocation" value="classpath:mybatis-mysql.xml"/>--> <!--mapper.xml所在位置--> <property name="mapperLocations"> <list> <value>classpath:mapper/*Mapper.xml</value> </list> </property> <!--需要使用别名的pojo类所在的包--> <property name="typeAliasesPackage" value="cn.com.meta.pojo"/> </bean> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="cn.com.meta.mapper"/> <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/> </bean> </beans>
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b. config.properties 配置
jdbc.url=jdbc:mysql://ip:port/db_name?useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true&useSSL=false jdbc.username=username jdbc.password=password jdbc.driver=com.mysql.jdbc.Driver
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注意上述的 spring-meta.xml、config.properteis 文件都放在 resources 目录下。
子模块整体结构如下：
c. 接口中新增方法
此时 Mapper 接口已经具备部分 CRUD 的能力，再新增一个自定义的 getNumberWeNeed 方法。
Mapper 接口：
public interface HelloMapper { int deleteByPrimaryKey(String tjId); int insert(Hello record); Hello selectByPrimaryKey(String tjId); List<Hello> selectAll(); // 根据月份、地区查找所需的数值型字段 BigDecimal getNumberWeNeed(@Param("column") String column, @Param("month") String month, @Param("area") String area); }
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相应的 XML 文件：
<select id="getNumberWeNeed" resultType="java.math.BigDecimal"> select ${column} from t_table_name where month = #{month} and area= #{area} </select>
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5. 编写测试类验证
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring-meta.xml"})
public class HelloMapperTest {
@Autowired
HelloMapper helloMapper;
@Test
public void testGetWeNeedNumber(){
// 比较两个 BigDecimal 类型的数必须用 compareTo
Assert.assertTrue(new BigDecimal("2").compareTo(helloMapper.getNumberWeNeed("total", "209905", "BeiJing")) == 0);
}
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以上。
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