Spring AOP Schema aop:config、tx:advice
一、 利用aop:config标签实现AOP
首先看个例子，如下
接口代码：
package com.lei.demo.aop.schema; public interface IHello { public void sayHello(); }
接口实现：
package com.lei.demo.aop.schema; public class HelloService implements IHello { public void sayHello() { System.out.println("-----Hello World!-----"); } }
接下来我们要实现AOP，即调用sayHello方法时切入通知。
1. 第一种方法aop:config中配置aop:pointcut和aop:aspect
定义一个切面支持类HelloAspect.java
package com.lei.demo.aop.schema; /* * 切面支持类 */ public class HelloAspect { //前置通知 public void beforeAdvice() { System.out.println("===========before advice"); } //后置最终通知 public void afterFinallyAdvice() { System.out.println("===========after finally advice"); } }
Xml配置：Spring-AOP-Schema.xml
<?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:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd"> <!-- 目标类 --> <bean id="helloService" class="com.lei.demo.aop.schema.HelloService" /> <bean id="helloAspect" class="com.lei.demo.aop.schema.HelloAspect" /> <!-- 配置切面 --> <!-- aop:advisor，是有顺序的，必须放在aop:pointcut之后 --> <aop:config> <aop:pointcut id="helloPointcut" expression="execution(* com.lei.demo.aop.schema..*.*(..))" /> <aop:aspect ref="helloAspect"> <!—以下使用了两种方法定义切入点 pointcut-ref和pointcut--> <aop:before pointcut-ref="helloPointcut" method="beforeAdvice" /> <aop:after pointcut="execution(* com.lei.demo.aop.schema..*.*(..))" method="afterFinallyAdvice" /> </aop:aspect> </aop:config> </beans>
以上配置中method="beforeAdvice"、method="afterFinallyAdvice"对应helloAspect中的方法
测试，App.java
package com.lei.demo.aop.schema; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class App { private static ApplicationContext ctx; public static void main(String[] args) { ctx = new ClassPathXmlApplicationContext("Spring-AOP-Schema.xml"); IHello helloService = ctx.getBean("helloService",IHello.class); helloService.sayHello(); } }
运行App.java，结果如下：
===========before advice
-----Hello World!-----
===========after finally advice
2. 第二种方法aop:config中配置aop:pointcut和aop:advisor
实现org.aopalliance.intercept.MethodInvocation接口，
HelloAroundAdvice.java如下：
package com.lei.demo.aop.schema; import java.lang.reflect.Method; import org.aopalliance.intercept.MethodInterceptor; import org.aopalliance.intercept.MethodInvocation; public class HelloAroundAdvice implements MethodInterceptor { public Object invoke(MethodInvocation arg0) throws Throwable { System.out.println("++++++before advice"); arg0.proceed(); System.out.println("++++++after advice"); return null; } }
Xml配置：Spring-AOP-Schema.xml
<?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:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd"> <!-- 目标类 --> <bean id="helloService" class="com.lei.demo.aop.schema.HelloService" /> <bean id="helloAspect" class="com.lei.demo.aop.schema.HelloAspect" /> <bean id="helloArroundAdvice" class="com.lei.demo.aop.schema.HelloAroundAdvice" /> <!-- 配置切面 --> <aop:config> <aop:pointcut id="helloPointcut" expression="execution(* com.lei.demo.aop.schema..*.*(..))" /> <aop:advisor advice-ref="helloArroundAdvice" pointcut-ref="helloPointcut"/> </aop:config> </beans>
仍然运行App.java，结果如下：
++++++before advice
-----Hello World!-----
++++++after advice
二、 AOP中加入事务，引入tx:advice
集成Hibernate时，需要引入事务，以下配置引用Spring 4.0.3和Hibernate 4.3.5
Spring-hibernate.xml如下：
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" 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-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd "> <!-- Hibernate4 --> <!-- 加载资源文件 其中包含变量信息，必须在Spring配置文件的最前面加载，即第一个加载--> <context:property-placeholder location="classpath:persistence-mysql.properties" /> <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="packagesToScan"> <list> <!-- 可以加多个包 --> <value>com.lei.demo.entity</value> </list> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop> <prop key="hibernate.dialect">${hibernate.dialect}</prop> <prop key="hibernate.show_sql">${hibernate.show_sql}</prop> </props> </property> </bean> <!-- 数据库映射 --> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${jdbc.driverClassName}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.user}" /> <property name="password" value="${jdbc.pass}" /> </bean> <!-- 配置Hibernate事务管理器 --> <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean> <!-- 配置事务异常封装 --> <bean id="persistenceExceptionTranslationPostProcessor" class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" /> <!-- 声明式容器事务管理 ,transaction-manager指定事务管理器为transactionManager--> <tx:advice id="txAdvice" transaction-manager="transactionManager"> <tx:attributes> <tx:method name="add*" propagation="REQUIRED" /> <tx:method name="get*" propagation="REQUIRED" /> <tx:method name="*" read-only="true" /> </tx:attributes> </tx:advice> <aop:config expose-proxy="true"> <!-- 只对业务逻辑层实施事务 --> <aop:pointcut id="txPointcut" expression="execution(* com.lei.demo.service..*.*(..))" /> <!-- Advisor定义，切入点和通知分别为txPointcut、txAdvice --> <aop:advisor pointcut-ref="txPointcut" advice-ref="txAdvice"/> </aop:config> </beans>
重点看一下tx:advice的配置
<tx:advice id="txAdvice" transaction-manager="transactionManager"> <tx:attributes> <tx:method name="add*" propagation="REQUIRED" /> <tx:method name="get*" propagation="REQUIRED" /> <tx:method name="*" read-only="true" /> </tx:attributes> </tx:advice>
意思是说，这个事务advice的管理者为transactionManager，而这个advice中规定了匹配add*、get*方法的传输方式为required，也就是说没有sessionFactory的时候会自动建立，有的时候就不会建立了。当然这只是规定了一个advice，你还需要指定一个aop:pointcut去引用它，例如下边的aop:config配置节。这样，这个advice就被织入到txPointcut这个pointcut上了。