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。

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