Spring AOP Schema aop:config、tx:advice

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。