應用Spring的註解方式實現AOP
一、使用例項
1、匯入需要的包
首先,為了使用Spring的AOP註解功能,必須在pom.xml中匯入如下幾個包。
<properties> <org.springframework-version>3.2.9.RELEASE</org.springframework-version> <commons-logging.version>1.1</commons-logging.version> <org.slf4j-version>1.7.2</org.slf4j-version> </properties> <dependencies> <!-- Spring --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${org.springframework-version}</version> <exclusions> <!-- Exclude Commons Logging in favor of SLF4j --> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${org.springframework-version}</version> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.dbunit</groupId> <artifactId>dbunit</artifactId> <version>2.4.6</version> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>${org.springframework-version}</version> <exclusions> <!-- Exclude Commons Logging in favor of SLF4j --> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>${commons-logging.version}</version> </dependency> <!-- Logging --> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>${org.slf4j-version}</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.15</version> <exclusions> <exclusion> <groupId>javax.mail</groupId> <artifactId>mail</artifactId> </exclusion> <exclusion> <groupId>javax.</groupId> <artifactId>jms</artifactId> </exclusion> <exclusion> <groupId>com.sun.jdmk</groupId> <artifactId>jmxtools</artifactId> </exclusion> <exclusion> <groupId>com.sun.jmx</groupId> <artifactId>jmxri</artifactId> </exclusion> </exclusions> <scope>runtime</scope> </dependency> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjrt</artifactId> <version>1.6.11</version> </dependency> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjweaver</artifactId> <version>1.6.11</version> </dependency> <dependency> <groupId>cglib</groupId> <artifactId>cglib</artifactId> <version>2.1</version> </dependency> </dependencies>
2、配置檔案applicationContext.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" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd <span style="color:#FF0000;">http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd</span> http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- 宣告註解方式載入bean--> <context:annotation-config/> <!-- 要載入的bean的包路徑--> <context:component-scan base-package="com.meituan.hyt.test.service"/> <!-- 自動掃描被@Aspect註解的bean--> <aop:aspectj-autoproxy/> <bean id="myInterceptor" class="com.meituan.hyt.test.aop.MyInterceptor"/> </beans>
3、編寫自己的業務介面和實現類,註解為spring bean
package com.meituan.hyt.test.service;
public interface PersonService {
public void save(String name);
public void update(int name);
public void throwException();
public String getPersonName();
}
package com.meituan.hyt.test.service; import org.springframework.stereotype.Service; @Service(value = "personService") public class PersonServiceImpl implements PersonService { @Override public String getPersonName() { System.out.println("我是getPersonName()方法。。。"); return "返回結果"; } @Override public void save(String name) { System.out.println("我是save()方法。。。"); } @Override public void update(int name) { System.out.println("我是update()方法。。。"); } @Override public void throwException() { System.out.println("我是throwException()方法。。。"); throw new RuntimeException("異常了。。"); } }
4、編寫切面
package com.meituan.hyt.test.aop;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
/**
* Created by heyutao on 15/11/2.
*/
@Aspect
public class MyInterceptor {
@Pointcut("execution(* com.meituan.hyt.test.service.*.*(..))")
//宣告一個切入點
private void anyMethod() {
}
@Before("anyMethod() && args(name)")//宣告前置通知
public void doBefore(String name) {
System.out.println("前置通知");
System.out.println("---" + name + "---");
}
@AfterReturning(pointcut = "anyMethod()", returning = "result")//聲明後置通知
public void doAfterReturning(String result) {
System.out.println("後置通知");
System.out.println("---" + result + "---");
}
@AfterThrowing(pointcut = "anyMethod()", throwing = "e")//宣告例外通知
public void doAfterThrowing(Exception e) {
System.out.println("例外通知");
System.out.println(e.getMessage());
}
@After("anyMethod()")//宣告最終通知
public void doAfter() {
System.out.println("最終通知");
}
@Around("anyMethod()")//宣告環繞通知
public Object doAround(ProceedingJoinPoint pjp) throws Throwable {
System.out.println("進入方法---環繞通知");
//顯示呼叫,確保被代理的方法被呼叫
Object o = pjp.proceed();
System.out.println("退出方法---環繞通知");
return o;
}
}
1、@Pointcut("execution(* com.meituan.hyt.test.service.*.*(..))")宣告一個切入點,可以攔截具體到某個方法,即在執行此方法之前、之後、最終、異常……時可以執行的其他業務方法(通知advice);
括號內的意思是:攔截某個方法,返回值是所有型別(第一個*),要攔截的是com.aoptest.service包及其子包下的所有類(..*)類下所有的方法(第三個.*)
2、args(name)
可以得到引數值,此時args(name)限制條件限定了"eexecution(* com.meituan.hyt.test.service.*.*(..))"中只攔截引數個數只有1個且型別為String的方法,而不是所有方法
5、編寫測試方法
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.meituan.hyt.test.service.PersonService;
/**
* Created by heyutao on 15/11/2.
*/
public class Main {
public static void main(String[] args) {
ApplicationContext cxt = new ClassPathXmlApplicationContext("applicationContext.xml");
PersonService personService = (PersonService) cxt.getBean("personService");
System.out.println("----------------save start------------");
personService.save("我是引數");
System.out.println("----------------save end------------");
System.out.println("----------------update start------------");
personService.update(100);
System.out.println("----------------update end------------");
System.out.println("----------------throwException start------------");
personService.throwException();
System.out.println("----------------throwException end------------");
System.out.println("----------------getPersonName start------------");
String result = personService.getPersonName();
System.out.println(result);
System.out.println("----------------getPersonName end------------");
}
}
6、執行結果
----------------save start------------進入方法---環繞通知
前置通知
---我是引數---
我是save()方法。。。
退出方法---環繞通知
最終通知
後置通知
---null---
----------------save end------------
----------------update start------------
進入方法---環繞通知
我是update()方法。。。
退出方法---環繞通知
最終通知
後置通知
---null---
----------------update end------------
----------------throwException start------------
進入方法---環繞通知
我是throwException()方法。。。
最終通知
例外通知
異常了。。
Exception in thread "main" java.lang.RuntimeException: 異常了。。
at com.meituan.hyt.test.service.PersonServiceImpl.throwException(PersonServiceImpl.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80)
at com.meituan.hyt.test.aop.MyInterceptor.doAround(MyInterceptor.java:51)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.aspectj.AspectJAfterAdvice.invoke(AspectJAfterAdvice.java:42)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.adapter.AfterReturningAdviceInterceptor.invoke(AfterReturningAdviceInterceptor.java:51)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:55)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at com.sun.proxy.$Proxy12.throwException(Unknown Source)
at Main.main(Main.java:24)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)
二、原理分析
1、名稱空間
<aop:aspectj-autoproxy proxy-target-class="true"> 該名稱空間會交給org.springframework.aop.config.AopNamespaceHandler處理,並在AspectJAutoProxyBeanDefinitionParser中,會執行parse方法解析配置:
public BeanDefinition parse(Element element, ParserContext parserContext) {
AopNamespaceUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(parserContext, element);
extendBeanDefinition(element, parserContext);
return null;
}
其中AopNamespaceUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(parserContext, element);目的是註冊AnnotationAwareAspectJAutoProxyCreator:
if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) {
BeanDefinition apcDefinition = registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME);
if (!cls.getName().equals(apcDefinition.getBeanClassName())) {
int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName());
int requiredPriority = findPriorityForClass(cls);
if (currentPriority < requiredPriority) {
apcDefinition.setBeanClassName(cls.getName());
}
}
return null;
}
即首先判斷當前容器中是否包含名字為AUTO_PROXY_CREATOR_BEAN_NAME的Bean, 如果包含:然後判斷優先順序,誰優先順序高誰獲勝,即最後那個獲勝的是實際的AutoProxyCreator。到此我們可以看到跟使用xml配置的方式 "<bean class="org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator">"配置沒什麼區別,除了沒有名字外。2、AspectJAwareAdvisorAutoProxyCreator
AspectJAwareAdvisorAutoProxyCreator的註冊,對於AOP的實現基本就靠這個類實現。AspectJAwareAdvisorAutoProxyCreator實現了SmartInstantiationAwareBeanPostProcessor這個介面,它是BeanPostProcessor的子介面。
BeanPostProcessor介面作用是:如果這個介面的某個實現類被註冊到某個容器,那麼spring容器的每個受管Bean在呼叫初始化方法之前,都會獲得該介面實現類的一個回撥,回撥方法包括postProcessBeforeInstantiation以及postProcessAfterInstantiation方法。AspectJAwareAdvisorAutoProxyCreator的實現原理就是在回撥方法中,找到所有的標有@AspectJ類中的增加方法,即標有@Before,@After,@AfterReturning,@Around等註解的方法,並且從中挑出能cut到當前bean的advisor,一個增強方法對應Advisor,最終形成一個Advisor的列表,並且是有序的集合,順序分別是Around,
Before, After, AfterReturning, AfterThrowing。然後將這個Advisor的列表作為引數,生成目標物件的代理物件,並返回。動態生成代理物件的方式有兩種:jdk動態代理和cglib。具體請參考http://blog.csdn.net/heyutao007/article/details/49738887