什么是事务，很通俗的话来说就是，我们日常生活中总会出现在银行转账的业务，加入A向B转账100元，此时A的账户中应该减少100元，B的账户中增加100元，但是如果在A转完账B还没有接受的时候，服务器出现了故障，一般银行的系统都会给出交易失败的提示，并且A的账户中总金额也不会变，那么这就类似一个事务。

　　1.事务是单个逻辑单元工作单位执行的一系列操作

　　2.多个操作作为整体向系统提交，要么都执行，要么都不执行

　　3.事务时一个不可分割的逻辑单元

事务的4大特性：原子性、一致性、隔离性、持久性（ACID）

下边我就模拟一个银行转账的事务：

首先导入依赖

<!-- https://mvnrepository.com/artifact/org.springframework/spring-context --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>5.1.0.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-core --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>5.1.0.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-beans --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-beans</artifactId> <version>5.1.0.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-expression --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-expression</artifactId> <version>5.1.0.RELEASE</version> </dependency> <!--以上4个是spring的核心--> <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver --> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjweaver</artifactId> <version>1.9.2</version> </dependency> <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjrt --> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjrt</artifactId> <version>1.9.2</version> </dependency> <!--以上两个是aop依赖--> <!-- https://mvnrepository.com/artifact/org.springframework/spring-tx --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>5.1.0.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc --> <!--spring自带的数据库连接依赖--> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>5.1.0.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --> <!--mysql数据库依赖--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.32</version> </dependency>

dao层接口

1 public interface AccountDao {2 void addmonkey();//向表中增加金额3 void submonkey();//向表中减少金额4 }

dao层实现类

 1 //dao层实现类需要继承JdbcDaoSupport，这是spring自带的数据库操作 2 public class AccountDaoImpl extends JdbcDaoSupport implements AccountDao { 3  @Override 4 public void addmonkey() { 5 //id为1的用户总金额增加100 6 String sql="update account set accountmonkey=accountmonkey+100 where accountid=1"; 7 this.getJdbcTemplate().update(sql); 8  } 9 10  @Override11 public void submonkey() {12 //id为2的用户总金额减少10013 String sql="update account set accountmonkey=accountmonkey-100 where accountid=2";14 this.getJdbcTemplate().update(sql);15  }16 }

service层接口

public interface AccountService { void changeMonkey();}

service实现类

public class AccountServiceImpl implements AccountService { private AccountDao dao; @Override public void changeMonkey() { dao.submonkey();//A先转账给B int result=5/0;//模拟异常，再调用完加钱的时候。 dao.addmonkey();//B接收money } public AccountDao getDao() { return dao; } public void setDao(AccountDao dao) { this.dao = dao; }}

实体类

1 public class Account {2 private int accountid;3 private String accountname;4 private Double accountmonkey;5 //省略set，get方法6 }

增强类

//增强类public class BeforeAdvice implements MethodBeforeAdvice, AfterReturningAdvice { @Override public void before(Method method, Object[] objects, Object o) throws Throwable { System.out.println("前置增强"); } @Override public void afterReturning(Object o, Method method, Object[] objects, Object o1) throws Throwable { System.out.println("后置增强"); }}

测试类

1 public class Test {2 public static void main(String[] args) {3 ApplicationContext context = new ClassPathXmlApplicationContext("/applictionContext.xml");4 AccountService bean = context.getBean(AccountService.class);5  bean.changeMonkey();6  }7 }

核心配置文件applicationContext.xml

 1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans xmlns="http://www.springframework.org/schema/beans" 3  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" 4  xmlns:context="http://www.springframework.org/schema/context" 5  xmlns:aop="http://www.springframework.org/schema/aop" 6  xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"> 7 <!--引入外部文件，将数据库配置文件引入到本文件中--> 8 <context:property-placeholder location="classpath:database.properties"/> 9 <!--dao层-->10 <bean id="dao" class="dao.impl.AccountDaoImpl">11 <!--注入数据源-->12 <property name="dataSource" ref="dataSource"/>13 </bean>14 <!--向容器中添加service层实现类-->15 <bean id="service" class="service.impl.AccountServiceImpl">16 <property name="dao" ref="dao"/>17 </bean>18 <!--向容器中添加通知的实现类-->19 <bean id="advice1" class="advice.BeforeAdvice"></bean>20 <!--顾问包装通知-->21 <bean id="advisor" class="org.springframework.aop.support.NameMatchMethodPointcutAdvisor">22 <property name="advice" ref="advice1"/>23 <property name="mappedName" value="say"/>24 </bean>25 <!--顾问代理生成器-->26 <bean class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">27 <property name="beanNames" value="service"/>28 <property name="interceptorNames" value="advisor"/>29 </bean>30 <!--数据源，使用的数据源是spring自带的，讲道理这个自带的数据源不怎么好-->31 <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">32 <property name="username" value="${jdbc.username}"/>33 <property name="password" value="${jdbc.password}"/>34 <property name="url" value="${jdbc.url}"/>35 <property name="driverClassName" value="${jdbc.driver}"/>36 </bean>37 <!--配置事务管理器-->38 <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">39 <property name="dataSource" ref="dataSource"/>40 </bean>41 <!--通知，tx标签是配置事务用的。propagation:事物的管理级别，isolation:事务的传播行为-->42 <tx:advice transaction-manager="transactionManager" id="ad" >43 <tx:attributes>44 <tx:method name="changeMonkey" propagation="REQUIRED" isolation="READ_COMMITTED"/>45 </tx:attributes>46 </tx:advice>47 <aop:config>48 <aop:pointcut id="pointcut" expression="execution(* service.*.*(..))"/>49 <aop:advisor advice-ref="ad" pointcut-ref="pointcut"/>50 </aop:config>51 </beans>

 这里呢一个简单的事务就已经配置好了。