AOP中关键性概念 :

①、连接点(Joinpoint)：程序执行过程中明确的点，如方法的调用，或者异常的抛出，

②、目标(Target)：被通知(被代理)的对象
?注1：完成具体的业务逻辑

③、通知(Advice)：在某个特定的连接点上执行的动作，同时Advice也是程序代码的具体实现，例 ? ? ? ? 如一个实现日志记录的代码(通知有些书上也称为处理)
?注2：完成切面编程

④、代理(Proxy)：将通知应用到目标对象后创建的对象(代理=目标+通知),
? ? ? ?例子：外科医生+护士
注3：只有代理对象才有AOP功能，而AOP的代码是写在通知的方法里面的

⑤、切入点(Pointcut)：多个连接点的集合，定义了通知应该应用到那些连接点。
? ? ? (也将Pointcut理解成一个条件，此条件决定了容器在什么情况下将通知和目标组合成代理返 ? ? ? ? ?回给外部程序)

⑥、适配器(Advisor)：适配器=通知(Advice)+切入点(Pointcut)

?AOP的核心点（通知）

1，前置通知

异常类

package com.hmf.exception;

public class PriceException extends RuntimeException {

?? ?public PriceException() {
?? ??? ?super();
?? ?}

?? ?public PriceException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
?? ??? ?super(message, cause, enableSuppression, writableStackTrace);
?? ?}

?? ?public PriceException(String message, Throwable cause) {
?? ??? ?super(message, cause);
?? ?}

?? ?public PriceException(String message) {
?? ??? ?super(message);
?? ?}

?? ?public PriceException(Throwable cause) {
?? ??? ?super(cause);
?? ?}
?? ?
}

接口IBookBiz有两个方法

package com.hmf.biz;

public interface IBookBiz {
?? ?// 购书
?? ?public boolean buy(String userName, String bookName, Double price);

?? ?// 发表评论
?? ?public void comment(String userName, String comments);
}

实现类BookBizImpl?继承接口并重写方法

package com.hmf.biz;

import com.hmf.exception.PriceException;

public class BookBizImpl implements IBookBiz {

?? ?public BookBizImpl() {
?? ??? ?super();
?? ?}

?? ?public boolean buy(String userName, String bookName, Double price) {
?? ??? ?if (null == price || price <= 0) {
?? ??? ??? ?//?通过控制台的输出方式模拟购书
?? ??? ??? ?throw new PriceException("book price exception");
?? ??? ?}
?? ??? ?System.out.println(userName + " buy " + bookName + ", spend " + price);
?? ??? ?return true;
?? ?}

?? ?public void comment(String userName, String comments) {
?? ??? ?//?通过控制台的输出方式模拟发表评论
?? ??? ?System.out.println(userName + " say:" + comments);
?? ?}

}

前置通知MyMethodBeforeAdvice 实现一个接口类代码?

package com.hmf.advice;

import java.lang.reflect.Method;
import java.util.Arrays;

import org.springframework.aop.MethodBeforeAdvice;

public class MyMethodBeforeAdvice implements MethodBeforeAdvice {
?? ?/**
?? ? * target：目标对象
?? ? * method：被触发目标对象的方法
?? ? * args：目标对象的目标方法携带的参数
?? ? */
?? ?
?? ?public void before(Method method, Object[] args, Object target) throws Throwable {
?? ??? ?String targetName = target.getClass().getName();
?? ??? ?String methodName = method.getName();
?? ??? ?String params = Arrays.toString(args);
?? ??? ?String msg = "买书评论前加系统日志："+targetName+"."+methodName+",前置通知携带的参数："+params;
?? ??? ?System.out.println(msg);

?? ?}

}

配置

<bean name="bookBiz" class="com.hmf.biz.BookBizImpl"></bean>

<bean name="myBefore" class="com.hmf.advice.MyMethodBeforeAdvice"></bean>


?? ?<bean class="org.springframework.aop.framework.ProxyFactoryBean"
?? ??? ?id="proxyFactoryBean">
?? ??? ?<property name="target" ref="bookBiz"></property>
?? ??? ?
?? ??? ?<property name="proxyInterfaces">
?? ??? ??? ?<list>
?? ??? ??? ??? ?<value>com.hmf.biz.IBookBiz</value>
?? ??? ??? ?</list>
?? ??? ?</property>
?? ??? ?<property name="interceptorNames">
?? ??? ??? ?<list>
?? ??? ??? ??? ?<value>myBefore</value>
?? ??? ??? ?</list>
?? ??? ?</property>
?? ?</bean>
?

常规业务代码（测试

package com.hmf.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.hmf.biz.IBookBiz;

public class AopTest {
?? ?public static void main(String[] args) {
?? ??? ?ApplicationContext applicationContext=new ClassPathXmlApplicationContext("/spring-context.xml");
?? ??? ?IBookBiz bookBiz =(IBookBiz) applicationContext.getBean("proxyFactoryBean");
?? ??? ?bookBiz.buy("小小与大鱼", "bb",1.1 );
?? ??? ?bookBiz.comment("你怎么有点可爱", "hhhh");
?? ?}
}
?? ?

三个参数?

?????* target：目标对象
?? ? * method：被触发目标对象的方法
?? ? * args：目标对象的目标方法携带的参数

结果?

2，后置通知?

后置通知代码类（MyAfterRetruningAdvice?）

package com.hmf.advice;

import java.lang.reflect.Method;
import java.util.Arrays;

import org.springframework.aop.MethodBeforeAdvice;

public class MyMethodBeforeAdvice implements MethodBeforeAdvice {
?? ?/**
?? ? * target：目标对象
?? ? * method：被触发目标对象的方法
?? ? * args：目标对象的目标方法携带的参数
?? ? */
?? ?
?? ?public void before(Method method, Object[] args, Object target) throws Throwable {
?? ??? ?String targetName = target.getClass().getName();
?? ??? ?String methodName = method.getName();
?? ??? ?String params = Arrays.toString(args);
?? ??? ?String msg = "买书评论前加系统日志："+targetName+"."+methodName+",前置通知携带的参数："+params;
?? ??? ?System.out.println(msg);

?? ?}

}

配置

?
<bean name="myAfter" class="com.hmf.advice.MyAfterReturningAdvice"></bean>

先运行前置再运行后置通知（结果

?3，环绕通知

环绕通知代码（MyMethodInterceptor?）

package com.hmf.advice;

import java.lang.reflect.Method;
import java.util.Arrays;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

/**
?* 环绕通知
?* @author Administrator
?*
?*/
public class MyMethodInterceptor implements MethodInterceptor {

?? ?public Object invoke(MethodInvocation invocation) throws Throwable {
?? ??? ?Object target = invocation.getThis();
?? ??? ?Method method = invocation.getMethod();
?? ??? ?Object[] args = invocation.getArguments();
?? ??? ?// a.jsp window.open(b.jsp)
?? ??? ?// b.jsp xxx->返回object->b.jsp window.close();window.getArguments;
?? ??? ?String targetName = target.getClass().getName();
?? ??? ?String methodName = method.getName();
?? ??? ?String params = Arrays.toString(args);
?? ??? ?String msg = "【环绕通知】：正在调用->" + targetName + "." + methodName + ",携带的参数：" + params;
?? ??? ?System.out.println(msg);
?? ??? ?Object returnValue = invocation.proceed();
?? ??? ?String msg2 = "【环绕通知】：目标对象所调用的方法的返回值：" + returnValue;
?? ??? ?System.out.println(msg2);
?? ??? ?return returnValue;
?? ?}

}

配置

<bean name="MyMethod" class="com.hmf.advice.MyMethodInterceptor"></bean>
?? ?
?? ?<bean class="org.springframework.aop.framework.ProxyFactoryBean"
?? ??? ?id="proxyFactoryBean">
?? ??? ?<property name="target" ref="bookBiz"></property>
?? ??? ?
?? ??? ?<property name="proxyInterfaces">
?? ??? ??? ?<list>
?? ??? ??? ??? ?<value>com.hmf.biz.IBookBiz</value>
?? ??? ??? ?</list>
?? ??? ?</property>
?? ??? ?<property name="interceptorNames">
?? ??? ??? ?<list>
?? ??? ??? ??? ?<value>myBefore</value>
?? ??? ??? ??? ?<value>myAfter</value>
?? ??? ??? ??? ?<value>MyMethod</value>
?? ??? ??? ?</list>
?? ??? ?</property>
?? ?</bean>

结果

4，异常通知

?package com.hmf.advice;

import org.springframework.aop.ThrowsAdvice;

import com.hmf.exception.PriceException;

/**
?* 异常通知
?* @author Administrator
?*
?*/
public class MyThrowsAdvice implements ThrowsAdvice {
?? ?public void afterThrowing( PriceException ex ) {
?? ??? ?System.out.println("价格输入有误，购买失败，请重新输入！！！");
?? ?}
}

配置

<bean name="MyThrows" class="com.hmf.advice.MyThrowsAdvice"></bean>
?? ?
?? ?<bean class="org.springframework.aop.framework.ProxyFactoryBean"
?? ??? ?id="proxyFactoryBean">
?? ??? ?<property name="target" ref="bookBiz"></property>
?? ??? ?
?? ??? ?<property name="proxyInterfaces">
?? ??? ??? ?<list>
?? ??? ??? ??? ?<value>com.hmf.biz.IBookBiz</value>
?? ??? ??? ?</list>
?? ??? ?</property>
?? ??? ?<property name="interceptorNames">
?? ??? ??? ?<list>
?? ??? ??? ??? ?<value>myBefore</value>
?? ??? ??? ??? ?<value>myAfter</value>
?? ??? ??? ??? ?<value>MyMethod</value>
?? ??? ??? ??? ?<value>MyThrows</value>
?? ??? ??? ?</list>
?? ??? ?</property>
?? ?</bean>