【SSM】Spring集成Mybatis

Spring框架集成Mybtis

为啥学习集成 Mybatis ORM 框架

虽然Spring中提供了JDBCTemplate模块，已经很大程度了解决了JDBC代码的复杂度，但它仍然是和Java代码写在一起的。反观 Mybatis 将 Sql 语句写在配置文件中，使得SQL语句和程序实现了松耦合。而且提供了些许标签，使得SQL可以是动态的。在ORM基础上想要更好的用Spring的DI、AOP、事务处理、Junit支持等实现成果，学会使用 Spring 框架集成 Mybatis 是大势所趋。

实现步骤

• 第一步：准备数据库表

• 第二步：IDEA中创建一个模块，并引入以下依赖

1. spring-context
2. spring-jdbc
3. mysql驱动
4. mybatis
5. mybatis-spring:mybatis提供的与spring框架集成的依赖
6. druid:德鲁伊连接池
7. junit

<dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>6.0.5</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>6.0.5</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.31</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.11</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>3.0.1</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.2.16</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.13</version><scope>test</scope></dependency></dependencies>

• 第三步：基于三层架构实现，所以提前创建好所有的包

1. XXXX.mapper
2. XXXX.service
3. XXXX.service.impl
4. XXXX.bean

• 第四步：编写bean Account，按bean规范创建

• 第五步：编写Mapper接口 AccountMapper接口，定义与数据库交互的方法

packagecom.ncpowernode.spring.mappers;importcom.ncpowernode.spring.bean.Account;importjava.util.List;publicinterfaceAccountMapper{List<Account>selectAll();AccountselectByActno(String actno);intinsert(Account account);intdeleteByActno(String actno);intupdate(Account account);}

• 第六步：编写mapper配置文件

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPEmapperPUBLIC"-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mappernamespace="com.ncpowernode.spring.mappers.AccountMapper"><selectid="selectAll"resultType="account">
        select * from t_act;
    </select><insertid="insert">
        insert into t_act values(#{actno},#{balance})
    </insert><deleteid="deleteByActno">
        delete from t_act where actno = #{actno};
    </delete><selectid="selectByActno"resultType="account">
        select * from t_act where actno = #{actno};
    </select><updateid="update">
        update t_act set balance = #{balance} where actno = #{actno};
    </update></mapper>

• 第七步：编写service接口和service接口的实现类

service接口

packagecom.ncpowernode.spring.service;importcom.ncpowernode.spring.bean.Account;importjava.util.List;publicinterfaceAccountService{intsave(Account act);intdeleteByActno(String actno);List<Account>getAll();voidtransfer(String fromActno,String toActno,double money);}

service实现

packagecom.ncpowernode.spring.service.impl;importcom.ncpowernode.spring.bean.Account;importcom.ncpowernode.spring.mappers.AccountMapper;importcom.ncpowernode.spring.service.AccountService;importorg.springframework.beans.factory.annotation.Autowired;importorg.springframework.beans.factory.annotation.Qualifier;importjava.util.List;@Service("accountService")@TransactionalpublicclassAccountServiceImplimplementsAccountService{@Autowired@Qualifier("accountMapper")privateAccountMapper accountMapper;@Overridepublicintsave(Account act){return accountMapper.insert(act);}@OverridepublicintdeleteByActno(String actno){return accountMapper.deleteByActno(actno);}@OverridepublicList<Account>getAll(){return accountMapper.selectAll();}@Overridepublicvoidtransfer(String fromActno,String toActno,double money){// 判断余额Account fromAccount = accountMapper.selectByActno(fromActno);if(fromAccount.getBalance()<money)thrownewRuntimeException("余额不足");// 更新数据库Account toAccount = accountMapper.selectByActno(toActno);
        fromAccount.setBalance(fromAccount.getBalance()-money);
        toAccount.setBalance(toAccount.getBalance()+money);int cnt = accountMapper.update(fromAccount);
        cnt += accountMapper.update(toAccount);// 判断业务是否实现成功if(cnt!=2)thrownewRuntimeException("转账失败");}}

• 第八步：编写jdbc.properties配置文件 数据库连接池相关信息

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/？？？
jdbc.username=？？？
jdbc.password=？？？

• 第九步：编写mybatis-config.xml核心配置文件

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPEconfigurationPUBLIC"-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><settings><!--驼峰命名自动映射，默认false--><settingname="mapUnderscoreToCamelCase"value="false"/><!--设置懒加载--><settingname="lazyLoadingEnabled"value="true"/><!--配置日志，可以帮助我们查看sql执行信息--><settingname="logImpl"value="STDOUT_LOGGING"/></settings></configuration>

• 第十步：编写spring.xml配置文件 组件扫描 引入外部的属性文件 数据源 SqlSessionFactoryBean配置（注入mybatis核心配置文件路径，指明别名包，注入数据源） Mapper扫描配置器（指定扫描的包） 事务管理器（DataSourceTransactionManager，注入数据源） 启动事务注解（注入事务管理器）

<?xml version="1.0" encoding="UTF-8"?><beansxmlns="http://www.springframework.org/schema/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"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd 
                            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd"><!--组件扫描--><context:component-scanbase-package="com.ncpowernode.spring.service"/><!--引入外部的属性文件--><context:property-placeholderlocation="jdbc.properties"/><!--数据源--><beanid="dataSource"class="com.alibaba.druid.pool.DruidDataSource"><propertyname="driverClassName"value="${jdbc.driver}"/><propertyname="url"value="${jdbc.url}"/><propertyname="username"value="${jdbc.username}"/><propertyname="password"value="${jdbc.password}"/></bean><!--配置SqlSessionFactoryBean--><beanclass="org.mybatis.spring.SqlSessionFactoryBean"><!--注入数据源--><propertyname="dataSource"ref="dataSource"/><!--指定别名包--><propertyname="typeAliasesPackage"value="com.ncpowernode.spring.bean"/><!--指定mybatis核心配置文件--><propertyname="configLocation"value="mybatis-config.xml"/></bean><!--配置Mapper扫描配置器--><!--主要扫描mapper接口，生成代理类--><beanclass="org.mybatis.spring.mapper.MapperScannerConfigurer"><propertyname="basePackage"value="com.ncpowernode.spring.mappers"/></bean><!--事务管理器--><beanid="txManager"class="org.springframework.jdbc.datasource.DataSourceTransactionManager"><propertyname="dataSource"ref="dataSource"/></bean><!--启动事务注解--><tx:annotation-driventransaction-manager="txManager"/></beans>

• 第十一步：编写测试程序，并添加事务，进行测试。

@TestpublicvoidtestSM(){ApplicationContext applicationContext =newClassPathXmlApplicationContext("spring.xml");AccountService accountService = applicationContext.getBean("accountService",AccountServiceImpl.class);
        accountService.getAll().forEach(System.out::println);
        accountService.transfer("act-001","act-002",10000.0);}

测试结果