本地事务系列之四：使用AOP

Spring AOP通过在文件中配置来管理事务，好处是对代码侵入性小。

Spring AOP使用AspectJ表达式来定义切点，所以pom文件加入：

<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjweaver</artifactId>
    <version>1.7.0</version>
</dependency>

FruitShop实现：

方法中除了使用继承自JdbcDaoSupport的JdbcTemplate来操作数据库外，没有其它与事务有关的代码：

public class AopTxFruitShop extends JdbcDaoSupport implements FruitShop {

	@Override
	public boolean purchase(int fruitId, String userName, int count) {
		String querySql = "SELECT PRICE FROM FRUIT WHERE ID = ?";
		String upStockSql = "UPDATE FRUIT_STOCK SET STOCK = STOCK - ? WHERE ID = ?";
		String upAccountSql = "UPDATE ACCOUNT SET BALANCE = BALANCE - ? WHERE USERNAME = ?";

		int price = getJdbcTemplate().queryForInt(querySql, new Object[] { fruitId });
		getJdbcTemplate().update(upStockSql, new Object[] { count, fruitId });
		getJdbcTemplate().update(upAccountSql, new Object[] { price * count, userName });
		return true;
	}
}

beans-fruitshop-aop.xml文件：

<?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:tx="http://www.springframework.org/schema/tx"
 xmlns:aop="http://www.springframework.org/schema/aop"
 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/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

  <!-- 当transaction-manager属性不指定时，Spring会搜索名称为transactionManager的bean -->
  <tx:advice id="fruitShopTxAdvice" transaction-manager="txManager">
  	<tx:attributes><!-- 可以指定多个需要事务的方法 -->
  		<tx:method name="purchase" /><!-- 支持通配符* -->
	</tx:attributes>
  </tx:advice>
  
  <aop:config>
  	<aop:pointcut id="fruitShopOperation" expression="execution(* com.john.tx.service.impl.AopTxFruitShop.*(..))" /><!-- 切点表达式 -->
	<aop:advisor advice-ref="fruitShopTxAdvice" pointcut-ref="fruitShopOperation" />
  </aop:config>

  <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
  	<property name="driverClassName" value="com.mysql.jdbc.Driver" />
	<property name="url" value="jdbc:mysql://localhost:3306/spring?characterEncoding=utf8" />
	<property name="username" value="spring" />
	<property name="password" value="123456" />
  </bean>
  
  <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
  	<property name="dataSource" ref="dataSource" />
  </bean>
  
  <bean id="aopTxFruitShop" class="com.john.tx.service.impl.AopTxFruitShop">
  	<property name="dataSource" ref="dataSource" />
  </bean>
</beans>

测试类：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:/beans-fruitshop-aop.xml" })
public class AopTxFruitShopTest {

	@Resource(name = "aopTxFruitShop")
	FruitShop aopTxFruitShop;
	
	@Test
	public void test() {
		int fruitId = 1;
		String userName = "user1";
		int count = 3;
		aopTxFruitShop.purchase(fruitId, userName, count);
	}
}