Spring AOP通过Pointcut指定在哪些类的那些方法上织入横切逻辑，通过Advice描述横切逻辑和方法的具体织入点(方法前、方法后、方法的两端等)。

此外，spring通过Advisor将advice和pointcut组装起来。也可以通过AspectJ描述切面信息，如下图所示

public interface UserService {public void save();public void update();public void delete();public void find();
}

public class UserServiceImpl implements UserService {@Overridepublic void save() {System.out.println("保存用户...");}@Overridepublic void update() {System.out.println("修改用户...");}@Overridepublic void delete() {System.out.println("删除用户...");}@Overridepublic void find() {System.out.println("查询用户...");}}

/*** 使用JDK的动态代理实现代理机制**/
public class MyJdbProxy implements InvocationHandler{private UserService userService;public MyJdbProxy(UserService userService){this.userService = userService;}public UserService createProxy(){// 生成UserSErvice的代理:UserService userServiceProxy = (UserService) Proxy.newProxyInstance(userService.getClass().getClassLoader(), userService.getClass().getInterfaces(), this);return userServiceProxy;}@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {// 判断是否是save方法:if("save".equals(method.getName())){// 增强:System.out.println("权限校验===========");return method.invoke(userService, args);}return method.invoke(userService, args);}}

public class SpringDemo1 {@Test// 没有代理的时候的调用方式public void demo1() {// 创建目标对象UserService userService = new UserServiceImpl();userService.save();userService.update();userService.delete();userService.find();}@Test// 使用代理public void demo2() {// 创建目标对象UserService userService = new UserServiceImpl();UserService proxy = new MyJdbProxy(userService).createProxy();proxy.save();proxy.update();proxy.delete();proxy.find();}
}

public class CustomerService {public void save(){System.out.println("保存客户...");}public void update(){System.out.println("修改客户...");}public void delete(){System.out.println("删除客户...");}public void find(){System.out.println("查询客户...");}
}

/*** 使用Cglib产生代理**/
public class MyCglibProxy implements MethodInterceptor{private CustomerService customerService;public MyCglibProxy(CustomerService customerService){this.customerService = customerService;}public CustomerService createProxy(){// 创建核心类:Enhancer enhancer = new Enhancer();// 设置父类:
        enhancer.setSuperclass(customerService.getClass());// 设置回调:enhancer.setCallback(this);// 创建代理:CustomerService customerServiceProxy = (CustomerService) enhancer.create();return customerServiceProxy;}@Overridepublic Object intercept(Object proxy, Method method, Object[] arg,MethodProxy methodProxy) throws Throwable {if("delete".equals(method.getName())){Object obj = methodProxy.invokeSuper(proxy, arg);System.out.println("日志记录==========");return obj;}return methodProxy.invokeSuper(proxy, arg);}
}

public class SpringDemo2 {@Testpublic void demo1(){CustomerService customerService = new CustomerService();customerService.save();customerService.update();customerService.delete();customerService.find();}@Testpublic void demo2(){CustomerService customerService = new CustomerService();// 产生代理:CustomerService proxy = new MyCglibProxy(customerService).createProxy();proxy.save();proxy.update();proxy.delete();proxy.find();}
}

<bean id="greetingAdvice" class="com.smart.advice.GreetingBeforeAdvice" />
<bean id="target" class="com.smart.advice.NaiveWaiter" />
<bean id="waiter"class="org.springframework.aop.framework.ProxyFactoryBean"p:proxyInterfaces="com.smart.advice.Waiter"p:target-ref="target"p:interceptorNames="greetingAdvice"/>

根据Advisor代理，proxyTargetClass设置为true，采用了CGLib动态代理技术（创建子类来代理target对象）

<bean id="waiterTarget" class="com.smart.advisor.Waiter" />
<bean id="sellerTarget" class="com.smart.advisor.Seller" />
<bean id="greetingAdvice" class="com.smart.advisor.GreetingBeforeAdvice" />
<!-- 正则表达式方法名匹配切面 -->
<bean id="regexpAdvisor"class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"p:advice-ref="greetingAdvice"><property name="patterns"><list><value>.*greet.*</value></list></property>
</bean>
<bean id="waiter1" class="org.springframework.aop.framework.ProxyFactoryBean"p:interceptorNames="regexpAdvisor" p:target-ref="waiterTarget"p:proxyTargetClass="true" />

可通过Advisor定义的切面信息或AspectJ定义的切面信息自动生成代理。不用逐个定义target类，它会将容器中的Advisor自动织入匹配的目标类中。

通过Advisor定义的切面自动生成代理 （在xml文件中定义Advisior）：

<bean id="waiter" class="com.smart.advisor.Waiter" />
<bean id="seller" class="com.smart.advisor.Seller" />
<bean id="greetingAdvice" class="com.smart.advisor.GreetingBeforeAdvice" />
<bean id="regexpAdvisor"class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"p:patterns=".*greet.*" p:advice-ref="greetingAdvice" />
<beanclass="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator" p:proxyTargetClass="true" />

通过AspectJ定义的切面自动生成代理 （在java文件中定义AspectJ）所以说AspectJ是语言级别的AOP实现。

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.context.annotation.Configuration;/*** Created by beyondLi on 2017/7/31.*/
//证明是一个配置文件(使用@Component也可以,因为点入后会发现@Configuration还是使用了@Component)
@Configuration
//证明是一个切面
@Aspect
public class ControllerAOP {//环绕aop//execution表达式 此表达式表示扫描controller下所有类的所有方法都执行此aop@Around("execution (* com.beyondli.controller..*.*(..))")public Object testAop(ProceedingJoinPoint pro) throws Throwable {//获取request请求提(需要时备用)//HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();//进入方法前执行的代码System.out.println("beginAround");//执行调用的方法Object proceed = pro.proceed();//方法执行完成后执行的方法System.out.println("endAround");return proceed;}}