Spring框架集成Mybtis

为啥学习集成 Mybatis ORM 框架实现步骤

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 spring-contextspring-jdbcmysql驱动mybatismybatis-spring:mybatis提供的与spring框架集成的依赖druid:德鲁伊连接池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 XXXX.mapperXXXX.serviceXXXX.service.implXXXX.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

package com.ncpowernode.spring.mappers;import com.ncpowernode.spring.bean.Account;import java.util.List;public interface AccountMapper {    List<Account> selectAll();        Account selectByActno(String actno);    int insert(Account account);    int deleteByActno(String actno);    int update(Account account);}

第六步：编写mapper配置文件

<?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.ncpowernode.spring.mappers.AccountMapper">    <select id="selectAll" resultType="account">        select * from t_act;    </select>    <insert id="insert">        insert into t_act values(#{actno},#{balance})    </insert>    <delete id="deleteByActno">        delete from t_act where actno = #{actno};    </delete>    <select id="selectByActno" resultType="account">        select * from t_act where actno = #{actno};    </select>    <update id="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

package com.ncpowernode.spring.service;import com.ncpowernode.spring.bean.Account;import java.util.List;public interface AccountService {    int save(Account act);    int deleteByActno(String actno);    List<Account> getAll();    void transfer(String fromActno,String toActno,double money);}

service实现

package com.ncpowernode.spring.service.impl;import com.ncpowernode.spring.bean.Account;import com.ncpowernode.spring.mappers.AccountMapper;import com.ncpowernode.spring.service.AccountService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import java.util.List;@Service("accountService")@Transactionalpublic class AccountServiceImpl implements AccountService {    @Autowired    @Qualifier("accountMapper")    private AccountMapper accountMapper;    @Override    public int save(Account act) {        return accountMapper.insert(act);    }    @Override    public int deleteByActno(String actno) {        return accountMapper.deleteByActno(actno);    }    @Override    public List<Account> getAll() {        return accountMapper.selectAll();    }    @Override    public void transfer(String fromActno, String toActno, double money) {        // 判断余额        Account fromAccount = accountMapper.selectByActno(fromActno);        if (fromAccount.getBalance()<money) throw new RuntimeException("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) throw new RuntimeException("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.Driverjdbc.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" ?><!DOCTYPE configuration        PUBLIC "-//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-->        <setting name="mapUnderscoreToCamelCase" value="false"/>        <!--设置懒加载-->        <setting name="lazyLoadingEnabled" value="true"/>        <!--配置日志，可以帮助我们查看sql执行信息-->        <setting name="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"?><beans xmlns="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-scan base-package="com.ncpowernode.spring.service"/>    <!--引入外部的属性文件-->    <context:property-placeholder location="jdbc.properties"/>    <!--数据源-->    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">        <property name="driverClassName" value="${jdbc.driver}"/>        <property name="url" value="${jdbc.url}"/>        <property name="username" value="${jdbc.username}"/>        <property name="password" value="${jdbc.password}"/>    </bean>    <!--配置SqlSessionFactoryBean-->    <bean class="org.mybatis.spring.SqlSessionFactoryBean">        <!--注入数据源-->        <property name="dataSource" ref="dataSource"/>        <!--指定别名包-->        <property name="typeAliasesPackage" value="com.ncpowernode.spring.bean"/>        <!--指定mybatis核心配置文件-->        <property name="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-->    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">        <property name="basePackage" value="com.ncpowernode.spring.mappers"/>    </bean>        <!--事务管理器-->    <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">        <property name="dataSource" ref="dataSource"/>    </bean>        <!--启动事务注解-->    <tx:annotation-driven transaction-manager="txManager"/>    </beans>

第十一步：编写测试程序，并添加事务，进行测试。

@Test    public void testSM(){        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("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