Spring Aop 與 AspectJ 有什么區(qū)別和聯(lián)系？

先說下區(qū)別

AspectJ

AspectJ是一個面向切面的框架，它擴(kuò)展了Java語言。AspectJ定義了AOP語法，所以它有一個專門的編譯器用來生成遵守Java字節(jié)編碼規(guī)范的Class文件。

spring aop

Spring提供了四種類型的Aop支持

• 基于經(jīng)典的SpringAOP

• 純POJO切面

• @ASpectJ注解驅(qū)動的切面

• 注入式AspectJ切面（其實(shí)與Spring并無多大的關(guān)系，這個就是使用AspectJ這個框架實(shí)現(xiàn)Aop編程）

基于經(jīng)典的SpringAop

其使用ProxyFactoryBean創(chuàng)建。

增強(qiáng)（通知）的類型有：

• 前置通知：org.springframework.aop.MethodBeforeAdvice
• 后置通知：org.springframework.aop.AfterReturningAdvice
• 環(huán)繞通知：org.aopalliance.intercept.MethodInterceptor
• 異常通知：org.springframework.aop.ThrowsAdvice

public?interface?IBookDao?{
????public?int?add()
????public?int?delete();
}
?
public?class?BookDaoImpl?implements?IBookDao{
????public?int?add()?{
????????System.out.println("正在添加圖書...");
????????return?0;
????}
????public?int?delete()?{
????????System.out.println("正在刪除圖書...");
????????return?0;
????}
}
?
//實(shí)現(xiàn)了MethodInterceptor的環(huán)繞增強(qiáng)類
public?class?MyAdvice?implements?MethodInterceptor{
?
????public?Object?invoke(MethodInvocation?invocation)?throws?Throwable?{
????????System.out.println("Around?Advice?before?method?invocation");
????????Object?o?=?invocation.proceed();
????????System.out.println("Around?Advice?after?method?invocation");
????????return?o;
????}
}

將每一個連接點(diǎn)都當(dāng)做切點(diǎn)（攔截每一個方法）

<bean?id="bookDao"?class="com.njust.learning.spring.service.BookDaoImpl">bean>
????<bean?id="myadvice"?class="com.njust.learning.spring.aop.MyAdvice">bean>
????<bean?id="bookDaoProxy"?class="org.springframework.aop.framework.ProxyFactoryBean">
????????<property?name="target"?ref="bookDao"/>
????????<property?name="proxyInterfaces"?value="com.njust.learning.spring.service.IBookDao"/>
????????<property?name="interceptorNames"?value="myadvice"/>
bean>

使用RegexMethodPointcutAdvisor針對某些特定的方法進(jìn)行攔截增強(qiáng)

<bean?id="bookDao"?class="com.njust.learning.spring.service.BookDaoImpl">bean>
???<bean?id="myadvice"?class="com.njust.learning.spring.aop.MyAdvice">bean>
???<bean?id="rmpAdvisor"?class="org.springframework.aop.support.RegexpMethodPointcutAdvisor">
???????
???????<property?name="patterns"?value=".*add"/>
???????<property?name="advice"?ref="myadvice"/>
???bean>

???<bean?id="bookDaoProxy"?class="org.springframework.aop.framework.ProxyFactoryBean">
???????<property?name="target"?ref="bookDao"/>
???????<property?name="proxyInterfaces"?value="com.njust.learning.spring.service.IBookDao"/>
???????<property?name="interceptorNames"?value="rmpAdvisor"/>
???bean>

注意:

像上面這樣，每定義一個dao都需要定義一個ProxyFactoryBean，顯得很麻煩，所以我們引入自動代理，也就是自動創(chuàng)建代理對象

BeanNameAutoProxyCreator

<bean?id="bookDao"?class="com.njust.learning.spring.service.BookDaoImpl">bean>
????<bean?id="myadvice"?class="com.njust.learning.spring.aop.MyAdvice">bean>
????<bean?id="rmpAdvisor"?class="org.springframework.aop.support.RegexpMethodPointcutAdvisor">
????????
????????<property?name="patterns"?value=".*add"/>
????????<property?name="advice"?ref="myadvice"/>
????bean>
?
????<bean?class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
????????<property?name="beanNames"?value="*Dao">property>
????????<property?name="interceptorNames"?value="rmpAdvisor">property>
????bean>

DefaultAdvisorAutoProxyCreator

<bean?id="bookDao"?class="com.njust.learning.spring.service.BookDaoImpl">bean>
????<bean?id="myadvice"?class="com.njust.learning.spring.aop.MyAdvice">bean>
????<bean?id="rmpAdvisor"?class="org.springframework.aop.support.RegexpMethodPointcutAdvisor">
????????
????????<property?name="patterns"?value=".*add"/>
????????<property?name="advice"?ref="myadvice"/>
????bean>
?
????
????<bean?class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator"/>

純POJO切面，需要使用XML進(jìn)行配置

public?interface?IBookDao?{
????public?int?add();
????public?int?delete();
}
?
public?class?BookDaoImpl?implements?IBookDao{
????public?int?add()?{
????????int?a?=?1/0;
????????System.out.println("正在添加圖書...");
????????return?0;
????}
?
????public?int?delete()?{
????????System.out.println("正在刪除圖書...");
????????return?0;
????}
}

public?class?PojoAdvice?{
????public?void?before(){
????????System.out.println("前置通知");
????}
????public?void?after(Object?returnval){
????????System.out.println("后置通知"+"，處理后的結(jié)果為："+returnval);
????}
????public?Object?around(ProceedingJoinPoint?proceedingJoinPoint)?throws?Throwable?{
????????System.out.println("環(huán)繞前置增強(qiáng)...");
????????Object?o?=?proceedingJoinPoint.proceed();
????????System.out.println("環(huán)繞后置增強(qiáng)...");
????????return?o;
????}
????public?void?afterThrowing(Throwable?e){
????????System.out.println("異常通知:"+e.getMessage());
????}
}

<bean?id="bookDao"?class="com.njust.learning.spring.service.BookDaoImpl">bean>
????<bean?id="pojoAdvice"?class="com.njust.learning.spring.pojoaop.PojoAdvice">bean>
????<aop:config>
????????<aop:pointcut?id="p"?expression="execution?(*?*.add(..))"/>
????????<aop:aspect?ref="pojoAdvice">
????????????<aop:before?method="before"?pointcut-ref="p">aop:before>
????????????
????????????<aop:after-returning?method="after"?pointcut-ref="p"?returning="returnval"/>
????????????<aop:around?method="around"?pointcut-ref="p"/>
????????????
????????????<aop:after-throwing?method="afterThrowing"?pointcut-ref="p"?throwing="e"/>
????????aop:aspect>
????aop:config>

再說說聯(lián)系

我們借助于Spring Aop的命名空間可以將純POJO轉(zhuǎn)換為切面，實(shí)際上這些POJO只是提供了滿足切點(diǎn)的條件時所需要調(diào)用的方法，但是，這種技術(shù)需要XML進(jìn)行配置，不能支持注解。

所以spring借鑒了AspectJ的切面，以提供注解驅(qū)動的AOP，本質(zhì)上它依然是Spring基于代理的AOP，只是編程模型與AspectJ完全一致，這種風(fēng)格的好處就是不需要使用XML進(jìn)行配置。

使用@Aspect方式，你就可以在類上直接一個@Aspect就搞定，不用費(fèi)事在xml里配了。但是這需要額外的jar包（aspectjweaver.jar）。因為spring直接使用AspectJ的注解功能，注意只是使用了它 的注解功能而已，并不是核心功能 。

SpringAop的底層技術(shù)依然是Jdk動態(tài)代理和Cglib。