Spring 之 AOP

AOP：面向切面编程。实现业务与其他功能的解耦。

首先引入：Spring Framework相关包、commons-logging、aopalliance.jar包

AOP包含4中通知：前置通知、后置通知、环绕通知、抛出通知

创建IUser接口

package springproject.demo;public interface IUser {public void pringName()  throws Exception ;}

实现IUser接口

package springproject.demo;public class User implements IUser{@Overridepublic void pringName() throws Exception {System.out.println("hello the world");//throw new Exception("");}}

创建前置通知：

package springproject.demo;import java.lang.reflect.Method;import org.springframework.aop.MethodBeforeAdvice;public class UserBefore implements MethodBeforeAdvice {private void print() {System.out.println("方法执行开始");}@Overridepublic void before(Method arg0, Object[] arg1, Object arg2)throws Throwable {print();}}

创建抛出通知：

package springproject.demo;import java.lang.reflect.Method;import org.springframework.aop.ThrowsAdvice;public class UserThrow implements ThrowsAdvice {public void afterThrowing(Method m, Object args, Object target,              Throwable subclass) {System.out.println("方法运行出错了！");}}

1、使用ProxyFactory：

package springproject.demo;import org.springframework.aop.framework.ProxyFactory;public class Main {public static void main(String[] args) throws Exception {testAOP();}private static void testAOP() throws Exception {ProxyFactory factory = new ProxyFactory();factory.addAdvice(new UserBefore());factory.setTarget(new User());User user = (User)factory.getProxy();user.pringName();}}

2、使用Spring IOC以及ProxyFactoryBean

创建Bean.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: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/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd"><bean id="user1" class="springproject.demo.User">    </bean><bean id="user2" class="org.springframework.aop.framework.ProxyFactoryBean">    <property name="target" ref="user1"></property>    <property name="interceptorNames" >        <list>            <value>myAspect</value>        </list>    </property></bean><bean id="myAspect" class="springproject.demo.UserBefore">   <!-- configure properties of aspect here as normal --></bean></beans>

访问:

package springproject.demo;import org.springframework.beans.factory.BeanFactory;import org.springframework.beans.factory.xml.XmlBeanFactory;import org.springframework.core.io.FileSystemResource;import org.springframework.core.io.Resource;public class Main {public static void main(String[] args) throws Exception {Resource resource = new FileSystemResource("bean.xml");BeanFactory factory = new XmlBeanFactory(resource);IUser bean = (IUser)factory.getBean("user2");bean.pringName();}}

3、Spring中@Aspectj的使用

需要引入：aspectjrt以及aspectjweaver包

创建目标对象，普通的java类

package springproject.demo;public class Person {private String mName;public String getName() {return mName;}public void setName(String name) {mName = name;}}

创建切面以及通知

package springproject.demo;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;import org.aspectj.lang.annotation.Pointcut;@Aspectpublic class NotVeryUsefulAspect {@Pointcut("execution(* springproject.demo.Person.*(..))")      public void foundMonkey(){}        @Before(value="foundMonkey()")      public void test() {    System.out.println("hello aspect");    }@Before("execution(* springproject.demo.Person.*(..))")public void print() {System.out.println("原来是这样");}}

在类上应用@Aspect注解

@Pointcut定义切面。括号内为切面表达式，代表横切demo包下Person类的所有方法。foundMonkey为切面签名，返回值必须为void。

@Before前置通知，应用在方法上。

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: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/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd"> <aop:aspectj-autoproxy /> <bean class="springproject.demo.NotVeryUsefulAspect" /> <bean id="person1" class="springproject.demo.Person">    <property name="name" value="xx"></property></bean></beans>

使用：

private static void testAspect() {  ApplicationContext context = new FileSystemXmlApplicationContext("bean.xml");    Person person = (Person) context.getBean("person1");  person.getName();}

在调用getName方法之前会先直线test和print方法。
注意：

以下代码是使用BeanFactory来获取Bean，但调用getName方法却不会执行test和print方法

Resource resource = new FileSystemResource("bean.xml");BeanFactory factory = new XmlBeanFactory(resource);Person mybean = (Person) factory.getBean("person1");System.out.print(mybean.getName());