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代理模式#xff1a;为其他对象提供一种代理以控制对这个对象的访问#xff0c;增强一个类中的某个方法#xff0c;对程序进行扩展。
动态代理可以在不修改类源码的前提下#xff0c;给类中方法增加额外逻辑
通过cglib来实现的代理对象的创建#xff1a;
基于…动态代理
代理模式为其他对象提供一种代理以控制对这个对象的访问增强一个类中的某个方法对程序进行扩展。
动态代理可以在不修改类源码的前提下给类中方法增加额外逻辑
通过cglib来实现的代理对象的创建
基于父子类被代理类是父类代理类是子类代理对象就是代理类的实例对象代理类是由cglib创建的
import org.springframework.cglib.proxy.Callback;
import org.springframework.cglib.proxy.Enhancer;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;
import java.lang.reflect.Method;// cglib动态代理单独使用
public class Test
{public static void main(String[] args){UserService target new UserService();// 通过cglib技术Enhancer enhancer new Enhancer();enhancer.setSuperclass(UserService.class);// 定义额外逻辑也就是代理逻辑enhancer.setCallbacks(new Callback[] {new MethodInterceptor(){Overridepublic Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy)throws Throwable{System.out.println(before...);
// // 写法一
// Object result methodProxy.invoke(target, objects);// // 写法二
// Object result method.invoke(target, objects);// 写法三Object result methodProxy.invokeSuper(o, objects);System.out.println(after...);return result;}}});// 动态代理所创建出来的UserService对象UserService userService (UserService)enhancer.create();// 执行这个userService的test方法时就会额外会执行一些其他逻辑userService.test();}
}public class UserService
{public void test(){System.out.println(test);}
}
利用JDK动态代理来生成一个代理对象
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;public class Test
{public static void main(String[] args){UserService target new UserService();// UserInterface接口的代理对象Object proxy Proxy.newProxyInstance(UserService.class.getClassLoader(),new Class[] {UserInterface.class}, new InvocationHandler(){Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable{System.out.println(before...);Object result method.invoke(target, args);System.out.println(after...);return result;}});// 注意这里必须是接口类型UserInterface如果是UserService类会报错UserInterface userService (UserInterface)proxy;userService.test();}
}public class UserService implements UserInterface
{Overridepublic void test(){System.out.println(test);}
}public interface UserInterface
{public void test();
}
注意代理对象proxy必须是接口类型 ProxyFactory
Spring对上面的两种动态代理技术进行了封装封装出来的类叫做ProxyFactory
表示创建代理对象的一个工厂使用起来更加方便
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.springframework.aop.framework.ProxyFactory;public class Test
{public static void main(String[] args){UserService target new UserService();ProxyFactory proxyFactory new ProxyFactory();proxyFactory.setTarget(target);proxyFactory.addAdvice(new MethodInterceptor(){Overridepublic Object invoke(MethodInvocation invocation)throws Throwable{System.out.println(before...);Object result invocation.proceed();System.out.println(after...);return result;}});UserInterface userService (UserInterface)proxyFactory.getProxy();userService.test();}
}public class UserService implements UserInterface
{Overridepublic void test(){System.out.println(test);}
}public interface UserInterface
{public void test();
}
ProxyFactory会自动判断是用cglib还是jdk动态代理
如果类实现了接口那么ProxyFactory底层就会用jdk动态代理
如果没有实现接口就会用cglib技术 Advice的分类
1、Before Advice方法之前执行
2、After returning advice方法return后执行
3、After throwing advice方法抛异常后执行
4、After (finally) advice方法执行完finally之后执行这是最后的比return更后
5、Around advice这是功能最强大的Advice可以自定义执行顺序 Advisor
一个Advisor是有一个Pointcut和一个Advice组成的通过Pointcut可以指定需要被代理的逻辑
可以通过Advisor来控制具体代理哪个方法
public class Test
{public static void main(String[] args){UserService target new UserService();ProxyFactory proxyFactory new ProxyFactory();proxyFactory.setTarget(target);proxyFactory.addAdvisor(new PointcutAdvisor(){Overridepublic Pointcut getPointcut(){return new StaticMethodMatcherPointcut(){Overridepublic boolean matches(Method method, Class? targetClass){return method.getName().equals(testAbc);}};}Overridepublic Advice getAdvice(){return new MethodInterceptor(){Overridepublic Object invoke(MethodInvocation invocation)throws Throwable{System.out.println(before...);Object result invocation.proceed();System.out.println(after...);return result;}};}Overridepublic boolean isPerInstance(){return false;}});UserInterface userService (UserInterface)proxyFactory.getProxy();userService.test();}
} 创建代理对象的方式
ProxyFactoryBean
public class UserService
{public void test(){System.out.println(test);}
}ComponentScan(value com.gax)
public class AppConfig
{Beanpublic ProxyFactoryBean userService(){UserService userService new UserService();ProxyFactoryBean proxyFactoryBean new ProxyFactoryBean();proxyFactoryBean.setTarget(userService);proxyFactoryBean.addAdvice(new MethodInterceptor(){Overridepublic Object invoke(MethodInvocation invocation)throws Throwable{System.out.println(before...);Object result invocation.proceed();System.out.println(after...);return result;}});return proxyFactoryBean;}
}public class Test
{public static void main(String[] args) {AnnotationConfigApplicationContext applicationContext new AnnotationConfigApplicationContext(AppConfig.class);UserService userServiceProxy (UserService)applicationContext.getBean(userService);userServiceProxy.test();}
}
上面这种方式只能针对某一个Bean
ProxyFactoryBean还有额外的功能比如可以把某个Advise或Advisor定义成为Bean然后在ProxyFactoryBean中进行设置
public class UserService
{public void test(){System.out.println(test);}
}ComponentScan(value com.gax)
public class AppConfig
{Beanpublic MethodInterceptor gaxAroundAdvise(){return new MethodInterceptor(){Overridepublic Object invoke(MethodInvocation invocation)throws Throwable{System.out.println(before...);Object result invocation.proceed();System.out.println(after...);return result;}};}Beanpublic ProxyFactoryBean userService(){UserService userService new UserService();ProxyFactoryBean proxyFactoryBean new ProxyFactoryBean();proxyFactoryBean.setTarget(userService);proxyFactoryBean.setInterceptorNames(gaxAroundAdvise);return proxyFactoryBean;}
}public class Test
{public static void main(String[] args) {AnnotationConfigApplicationContext applicationContext new AnnotationConfigApplicationContext(AppConfig.class);UserService userServiceProxy (UserService)applicationContext.getBean(userService);userServiceProxy.test();}
} BeanNameAutoProxyCreator
ProxyFactoryBean需要自己指定被代理的对象BeanNameAutoProxyCreator可以通过指定某个bean的名字来对该bean进行代理
通过BeanNameAutoProxyCreator可以对批量的Bean进行AOP并且指定了代理逻辑指定了一个InterceptorName也就是一个Advise前提条件是这个Advise也得是一个Bean这样Spring才能找到的但是BeanNameAutoProxyCreator的缺点很明显它只能根据beanName来指定想要代理的Bean。
Component
public class UserService
{public void test(){System.out.println(test);}
}ComponentScan(value com.gax)
public class AppConfig
{Beanpublic MethodInterceptor gaxAroundAdvise(){return new MethodInterceptor(){Overridepublic Object invoke(MethodInvocation invocation)throws Throwable{System.out.println(before...);Object result invocation.proceed();System.out.println(after...);return result;}};}Beanpublic BeanNameAutoProxyCreator beanNameAutoProxyCreator(){BeanNameAutoProxyCreator beanNameAutoProxyCreator new BeanNameAutoProxyCreator();beanNameAutoProxyCreator.setBeanNames(userSe*);beanNameAutoProxyCreator.setInterceptorNames(gaxAroundAdvise);beanNameAutoProxyCreator.setProxyTargetClass(true);return beanNameAutoProxyCreator;}
}public class Test
{public static void main(String[] args) {AnnotationConfigApplicationContext applicationContext new AnnotationConfigApplicationContext(AppConfig.class);UserService userServiceProxy (UserService)applicationContext.getBean(userService);userServiceProxy.test();}
} DefaultAdvisorAutoProxyCreator Component
public class UserService
{public void test(){System.out.println(test);}
}ComponentScan(value com.gax)
public class AppConfig
{Beanpublic MethodInterceptor gaxAroundAdvise(){return new MethodInterceptor(){Overridepublic Object invoke(MethodInvocation invocation)throws Throwable{System.out.println(before...);Object result invocation.proceed();System.out.println(after...);return result;}};}Beanpublic DefaultPointcutAdvisor defaultPointcutAdvisor(){NameMatchMethodPointcut pointcut new NameMatchMethodPointcut();pointcut.addMethodName(test);DefaultPointcutAdvisor defaultPointcutAdvisor new DefaultPointcutAdvisor();defaultPointcutAdvisor.setPointcut(pointcut);defaultPointcutAdvisor.setAdvice(gaxAroundAdvise());return defaultPointcutAdvisor;}Beanpublic DefaultAdvisorAutoProxyCreator defaultAdvisorAutoProxyCreator(){DefaultAdvisorAutoProxyCreator defaultAdvisorAutoProxyCreator new DefaultAdvisorAutoProxyCreator();return defaultAdvisorAutoProxyCreator;}
}public class Test
{public static void main(String[] args) {AnnotationConfigApplicationContext applicationContext new AnnotationConfigApplicationContext(AppConfig.class);UserService userServiceProxy (UserService)applicationContext.getBean(userService);userServiceProxy.test();}
}
通过DefaultAdvisorAutoProxyCreator会直接去找所有Advisor类型的Bean根据Advisor中的PointCut和Advice信息确定要代理的Bean以及代理逻辑。
简化成注解方式
Aspect
Component
public class GaxAspect
{Before(execution(public void com.gax.service.UserService.test()))public void gaxBefore(JoinPoint joinPoint) {System.out.println(gaxBefore);}
}
要代理的类表达式
代理逻辑被Before修饰的方法
Spring只要去解析这些注解就好了解析之后得到对应的Pointcut对象、Advice对象生成Advisor对象扔进ProxyFactory中进而产生对应的代理对象具体怎么解析这些注解就是EnableAspectJAutoProxy注解所要做的事情
