下面所有代码和示例仅仅是为了讲解spring aop，不能用于实际开发，因为实际没有这样用的，但是看看，理解下肯定是有好处的。
示例：对于更新或者删除用户来说，我们要进行事务管理，更新或删除之前要打开事务，之后要提交事务。
这里以更新来作为示例。
spring可以利用jdk或cglid来生成动态代理，我们直接利用cglib对类进行代理，不创建interface了。
UserService：
package spring3.aop.aop1;
public class UserService {
public void updUser() {
System.out.println("UserService updUser!");
}
}
创建前置增强 OpenTransaction：
package spring3.aop.aop1;
import java.lang.reflect.Method;
import org.springframework.aop.MethodBeforeAdvice;
public class OpenTransaction implements MethodBeforeAdvice {
/**
* 前置增强
*
* @param method 目标类方法
* @param args 目标类方法的入参
* @param obj 目标类实例
*/
@Override
public void before(Method method, Object[] args, Object obj)
throws Throwable {
System.out.println("Open Transaction");
}
}
创建后置增强 CommitTransaction：
package spring3.aop.aop1;
import java.lang.reflect.Method;
import org.springframework.aop.AfterReturningAdvice;
public class CommitTransaction implements AfterReturningAdvice {
/**
* 后置增强
*
* @param returnObj 目标类方法返回的结果
* @param method 目标类方法
* @param args 目标类方法的入参
* @param obj 目标类实例
*/
@Override
public void afterReturning(Object returnObj, Method method, Object[] args,
Object obj) throws Throwable {
System.out.println("Close Transaction");
}
}
xml配置：
<?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:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="beforeAdvice" class="spring3.aop.aop1.OpenTransaction"/>
<bean id="afterAdvice" class="spring3.aop.aop1.CommitTransaction"/>
<bean id="target" class="spring3.aop.aop1.UserService"/>
<bean id="userService" class="org.springframework.aop.framework.ProxyFactoryBean"
p:interceptorNames="beforeAdvice, afterAdvice"
p:target-ref="target"/>
</beans>
我们可以通过编码方式和配置方式来完成织入，现在我们来写测试类 TestAdvice：
package spring3.aop.aop1;
import org.springframework.aop.AfterReturningAdvice;
import org.springframework.aop.BeforeAdvice;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestAdvice {
public static void main(String[] args) {
// 通过编码方式来织入增强 START
UserService target = new UserService();
BeforeAdvice beforeAdvice = new OpenTransaction();
AfterReturningAdvice afterAdvice = new CommitTransaction();
// Spring提供的代理工厂
ProxyFactory pf = new ProxyFactory();
// 设定代理目标类
pf.setTarget(target);
// 为代理目标类织入增强
pf.addAdvice(beforeAdvice);
pf.addAdvice(afterAdvice);
// 生成代理实例
target = (UserService) pf.getProxy();
target.updUser();
// 通过编码方式来织入增强 END
System.out.println("");
// 通过XML配置方式来织入增强 START
ApplicationContext app = new ClassPathXmlApplicationContext(
"spring3/aop/aop1/aop.xml");
UserService userService = (UserService) app.getBean("userService");
userService.updUser();
// 通过XML配置方式来织入增强 START
}
}
测试结果：
Open Transaction UserService updUser! Close Transaction 4 12, 2013 1:45:44 午後 org.springframework.context.support.AbstractApplicationContext prepareRefresh 情報: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@15ede11: startup date [Fri Apr 12 13:45:44 CST 2013]; root of context hierarchy 4 12, 2013 1:45:44 午後 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions 情報: Loading XML bean definitions from class path resource [spring3/aop/aop1/aop.xml] 4 12, 2013 1:45:45 午後 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons 情報: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1a3eaa8: defining beans [beforeAdvice,afterAdvice,target,userService,aroundInterceptor,userService1]; root of factory hierarchy Open Transaction UserService updUser! Close Transaction
上面测试类程序中使用了org.springframework.aop.framework.ProxyFactory，它利用cglib或者jdk技术来创建代理，如果利用ProxyFactory.setInterfaces(arg0)方法来对特定接口来实现代理的话，ProxyFactory会选择利用jdk技术生成代理；如果没有指定针对接口代理或者指定ProxyFactory.setOptimize(true)（启用优化）时，ProxyFactory会选择利用cglib技术生成代理。
注意，如果ProxyFactory.setOptimize(true)设定true时，即使指定对接口进行代理，也会利用cglib技术来生成代理。
环绕增强 AroundInterceptor：
package spring3.aop.aop1;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
public class AroundInterceptor implements MethodInterceptor {
@Override
public Object invoke(MethodInvocation invocation) throws Throwable {
System.out.println("Open Transaction");
Object obj = invocation.proceed();
System.out.println("Close Transaction");
return obj;
}
}
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:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="target" class="spring3.aop.aop1.UserService"/>
<bean id="aroundInterceptor" class="spring3.aop.aop1.AroundInterceptor"/>
<bean id="userService1" class="org.springframework.aop.framework.ProxyFactoryBean"
p:interceptorNames="aroundInterceptor"
p:target-ref="target"/>
</beans>
测试类
package spring3.aop.aop1;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestAdvice {
public static void main(String[] args) {
UserService target = new UserService();
AroundInterceptor inteceptor = new AroundInterceptor();
ProxyFactory pf = new ProxyFactory();
pf.addAdvice(inteceptor);
pf.setTarget(target);
target = (UserService) pf.getProxy();
target.updUser();
System.out.println("");
ApplicationContext app = new ClassPathXmlApplicationContext(
"spring3/aop/aop1/aop.xml");
UserService userService1 = (UserService) app.getBean("userService1");
userService1.updUser();
}
}
测试结果：
Open Transaction UserService updUser! Close Transaction 4 12, 2013 1:57:55 午後 org.springframework.context.support.AbstractApplicationContext prepareRefresh 情報: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1565e9d: startup date [Fri Apr 12 13:57:55 CST 2013]; root of context hierarchy 4 12, 2013 1:57:55 午後 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions 情報: Loading XML bean definitions from class path resource [spring3/aop/aop1/aop.xml] 4 12, 2013 1:57:55 午後 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons 情報: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@196de7e: defining beans [target,aroundInterceptor,userService1]; root of factory hierarchy Open Transaction UserService updUser! Close Transaction