Spring aop 简单总结
先用jdk，cglib模拟下：
使用JDK动态代理
//当目标类实现了接口，我们可以使用jdk的Proxy来生成代理对象。
package cn.zyj15.aop;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import cn.zyj15.service.impl.PersonServiceBean;
/**
*
* @author Administrator
*实现InvocationHandler接口的即为代理，记实现invoke方法
*/
public class JDKProxyFactory implements InvocationHandler {
private Object targetObject;
public Object createProxyIntance(Object targetObject){
this.targetObject = targetObject;
//从newProxyInstance方法看出用jdk实现代理必须实现接口
/*
* 第一个参数设置代码使用的类装载器,一般采用跟目标类相同的类装载器
* 第二个参数设置代理类实现的接口
* 第三个参数设置回调对象,当代理对象的方法被调用时,会委派给该参数指定对象的invoke方法
*/
return Proxy.newProxyInstance(this.targetObject.getClass().getClassLoader(),
this.targetObject.getClass().getInterfaces(), this);
}
@Override
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {//环绕通知
PersonServiceBean bean = (PersonServiceBean) this.targetObject;
Object result = null;
if(bean.getUser()!=null){
//..... advice()-->前置通知
try {
result = method.invoke(targetObject, args);//把方法调用委派给目标对象
// afteradvice() -->后置通知
} catch (RuntimeException e) {
//exceptionadvice()--> 例外通知
}finally{
//finallyadvice(); -->最终通知
}
}else {
System.out.println("没有权限！");
}
return result;
}
}
package junit.test15;
import static org.junit.Assert.*;
import org.junit.Test;
import cn.zyj15.aop.JDKProxyFactory;
import cn.zyj15.service.PersonService;
import cn.zyj15.service.impl.PersonServiceBean;
public class AOPTest {
@Test
public void jdktest() {
JDKProxyFactory factory = new JDKProxyFactory();
//必须用接口
PersonService service = (PersonService) factory.createProxyIntance(new PersonServiceBean(null));
service.save("888");
}
}
使用CGLIB生成代理
//CGLIB可以生成目标类的子类，并重写父类非final修饰符的方法。
package cn.zyj16.aop;
import java.lang.reflect.Method;
import cn.zyj16.service.impl.PersonServiceBean;
import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
public class CGlibProxyFactory implements MethodInterceptor{
private Object targetObject;//代理的目标对象
public Object createProxyIntance(Object targetObject){
this.targetObject = targetObject;
Enhancer enhancer = new Enhancer();//该类用于生成代理对象
enhancer.setSuperclass(this.targetObject.getClass());//设置代理类的父类。CGLIB可以生成目标类的子类，并重写父类非final修饰符的方法。
enhancer.setCallback(this);//设置回调方法
return enhancer.create();//创建代理对象
}
public Object intercept(Object proxy, Method method, Object[] args,
MethodProxy methodProxy) throws Throwable {
PersonServiceBean bean = (PersonServiceBean) this.targetObject;
Object result = null;
if(bean.getUser()!=null){
result = methodProxy.invoke(targetObject, args);
}
return result;
}
}
package junit.test16;
import static org.junit.Assert.*;
import org.junit.Test;
import cn.zyj16.service.PersonService;
import cn.zyj16.service.impl.PersonServiceBean;
import cn.zyj16.aop.CGlibProxyFactory;
public class AOPTest {
@Test public void cglibTest2(){
CGlibProxyFactory factory = new CGlibProxyFactory();
//此事创建的代理对象是PersonServiceBean的子类！
PersonServiceBean service = (PersonServiceBean) factory.createProxyIntance(new PersonServiceBean("xxx"));
service.save("999");
}
}
AOP中的概念
Aspect(切面):指横切性关注点的抽象即为切面,它与类相似,只是两者的关注点不一样,类是对物体特征的抽象,而切面横切性关注点的抽象.
joinpoint(连接点):所谓连接点是指那些被拦截到的点。在spring中,这些点指的是方法,因为spring只支持方法类型的连接点,实际上joinpoint还可以是field或类构造器)
Pointcut(切入点):所谓切入点是指我们要对那些joinpoint进行拦截的定义.
Advice(通知):所谓通知是指拦截到joinpoint之后所要做的事情就是通知.通知分为前置通知,后置通知,异常通知,最终通知,环绕通知
Target(目标对象):代理的目标对象
Weave(织入):指将aspects应用到target对象并导致proxy对象创建的过程称为织入.
Introduction(引入):在不修改类代码的前提下, Introduction可以在运行期为类动态地添加一些方法或Field.
使用Spring进行面向切面（AOP）编程
要进行AOP编程，首先我们要在spring的配置文件中引入aop命名空间：
<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-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
</beans>
Spring提供了两种切面声明方式，实际工作中我们可以选用其中一种：
基于XML配置方式声明切面。
基于注解方式声明切面。
首先启动对@AspectJ注解的支持(蓝色部分)：
<?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:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
<aop:aspectj-autoproxy/>
<bean id="myInterceptor" class="cn.zyj17.service.MyInterceptor"/>
<bean id="personService" class="cn.zyj17.service.impl.PersonServiceBean"></bean>
</beans>
package cn.zyj17.service;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
/**
* 切面
*
*/
@Aspect
public class MyInterceptor {
@Pointcut("execution (* cn.zyj17.service.impl.PersonServiceBean.*(..))")
private void anyMethod() {}//声明一个切入点
@Before("anyMethod() && args(name)")
public void doAccessCheck(String name) {
System.out.println("前置通知:"+ name);
}
@AfterReturning(pointcut="anyMethod()",returning="result")
public void doAfterReturning(String result) {
System.out.println("后置通知:"+ result);
}
@After("anyMethod()")
public void doAfter() {
System.out.println("最终通知");
}
@AfterThrowing(pointcut="anyMethod()",throwing="e")
public void doAfterThrowing(Exception e) {
System.out.println("例外通知:"+ e);
}
@Around("anyMethod()")
public Object doBasicProfiling(ProceedingJoinPoint pjp) throws Throwable {
//if(){//判断用户是否在权限
System.out.println("进入方法");
Object result = pjp.proceed();
System.out.println("退出方法");
//}
return result;
}
}
package junit.test17;
import org.junit.BeforeClass;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import cn.zyj17.service.PersonService;
public class SpringAOPTest {
@BeforeClass
public static void setUpBeforeClass() throws Exception {
}
@Test public void interceptorTest(){
ApplicationContext cxt = new ClassPathXmlApplicationContext("beans.xml");
PersonService personService = (PersonService)cxt.getBean("personService");//接口
personService.save("xx");
}
}
基于基于XML配置方式声明切面
<?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:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
<aop:aspectj-autoproxy/>
<bean id="personService" class="cn.zyj19.service.impl.PersonServiceBean"></bean>
<bean id="aspetbean" class="cn.zyj19.service.MyInterceptor"/>
<aop:config>
<aop:aspect id="asp" ref="aspetbean">
<aop:pointcut id="mycut" expression=" execution(* cn.zyj19.service..*.*(..))"/>
<aop:before pointcut-ref="mycut" method="doAccessCheck"/>
<aop:after-returning pointcut-ref="mycut" method="doAfterReturning"/>
<aop:after-throwing pointcut-ref="mycut" method="doAfterThrowing"/>
<aop:after pointcut-ref="mycut" method="doAfter"/>
<aop:around pointcut-ref="mycut" method="doBasicProfiling"/>
</aop:aspect>
</aop:config>
</beans>
package cn.zyj19.service;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
/**
* 切面
*
*/
public class MyInterceptor {
public void doAccessCheck() {
System.out.println("前置通知");
}
public void doAfterReturning() {
System.out.println("后置通知");
}
public void doAfter() {
System.out.println("最终通知");
}
public void doAfterThrowing() {
System.out.println("例外通知");
}
public Object doBasicProfiling(ProceedingJoinPoint pjp) throws Throwable {
System.out.println("进入方法");
Object result = pjp.proceed();
System.out.println("退出方法");
return result;
}
}
package junit.test19;
import org.junit.BeforeClass;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import cn.zyj19.service.PersonService;
public class SpringAOPTest {
@BeforeClass
public static void setUpBeforeClass() throws Exception {
}
@Test public void interceptorTest(){
ApplicationContext cxt = new ClassPathXmlApplicationContext("beans.xml");
PersonService personService = (PersonService)cxt.getBean("personService");
personService.save("xx");
}
}