目录
AOP即面向切面编程
主要作用:
将核心的业务功能与非核心的业务功能进行分离;
将核心的业务功能写到目标对象中,将非核心的业务功能写到通知中
专业名词:
通知、连接点、目标对象、切入点、代理、适配器
日常开发中通常的应用场景:
事务管理、日志
事务的开启:前置通知
事务的提交:后置通知
事务的回滚:异常通知
让我们可以 “专心做事”
//案例: public void doSameBusiness (long lParam,String sParam){ // 记录日志 log.info("调用 doSameBusiness方法,参数是:"+lParam); // 输入合法性验证 if (lParam<=0){ throws new IllegalArgumentException("xx应该大于0"); } if (sParam==null || sParam.trim().equals("")){ throws new IllegalArgumentException("xx不能为空"); } // 异常处理 try{ ... }catch(...){ }catch(...){ } // 事务控制 tx.commit(); }
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.
目标(Target):被通知(被代理)的对象
完成具体的业务逻辑
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)
完成切面编程代理(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
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)适配器(Advisor):适配器=通知(Advice)+切入点(Pointcut)
以书籍的增删改查为例,
实现org.springframework.aop.MethodBeforeAdvice接口
买书、评论前加系统日志。
BookBiz
- package com.oyang.aop.biz;
-
- public interface BookBiz {
- // 购书
- public boolean buy(String userName, String bookName, Double price);
-
- // 发表书评
- public void comment(String userName, String comments);
- }
BookBizImpl
- package com.oyang.aop.biz.impl;
-
- import com.oyang.aop.biz.BookBiz;
- import com.oyang.aop.exception.PriceException;
-
- public class BookBizImpl implements BookBiz {
-
- public BookBizImpl() {
- super();
- }
-
- public boolean buy(String userName, String bookName, Double price) {
- // 通过控制台的输出方式模拟购书
- if (null == price || price <= 0) {
- throw new PriceException("book price exception");
- }
- // logDao.add-->sout("买书相关日志...")
- 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书评
- System.out.println(userName + " say:" + comments);
- // System.out.println("买书返利...");
- }
-
- }
PriceException
- package com.oyang.aop.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);
- }
-
- }
spring-context.xml配置
- <beans default-autowire="byType" 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.xsd
- http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
- http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">
-
- beans>
MyMethodBeforeAdivce
- package com.oyang.aop.advice;
-
- import java.lang.reflect.Method;
- import java.util.Arrays;
-
- import org.springframework.aop.MethodBeforeAdvice;
- /**
- * 前置通知
- * 买书、评论前加系统日志
- * @author Administrator
- *
- */
- public class MyMethodBeforeAdivce implements MethodBeforeAdvice{
-
- @Override
- public void before(Method arg0, Object[] arg1, Object arg2) throws Throwable {
- //拿到目标对象的类名
- String clzName = arg2.getClass().getName();
- //当前调用的方法是
- String methodName = arg0.getName();
- //当前调用方法所传递参数
- String args = Arrays.toString(arg1);
- System.out.println("[系统日志]:"+clzName+"."+methodName+"这个方法被调用,传递的参数为:"+args);
-
- }
-
- }
spring-context.xml配置
- <bean class="com.oyang.aop.biz.impl.BookBizImpl" id="bookBiz">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodBeforeAdivce" id="myBefore">bean>
-
- <bean class="org.springframework.aop.framework.ProxyFactoryBean" id="bookProxy">
-
- <property name="target" ref="bookBiz">property>
-
- <property name="proxyInterfaces">
- <list>
- <value>com.oyang.aop.biz.BookBizvalue>
- list>
- property>
-
- <property name="interceptorNames">
- <list>
- <value>myBeforevalue>
- list>
- property>
- bean>
Demo1
- package com.oyang.aop.test;
-
- import org.springframework.context.support.ClassPathXmlApplicationContext;
-
- import com.oyang.aop.biz.BookBiz;
-
- public class Demo1 {
- public static void main(String[] args) {
- ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/spring-context.xml");
- // BookBiz bean = (BookBiz) context.getBean("bookBiz");
- BookBiz bean = (BookBiz) context.getBean("bookProxy");
- bean.buy("欧阳", "完美世界", 32.9d);
- bean.comment("荒", "谁敢言无敌,哪个敢言不败!");
- }
- }
实现org.springframework.aop.AfterReturningAdvice接口
买书返利(存在bug)
MyAfterReturningAdvice
- package com.oyang.aop.advice;
-
- import java.lang.reflect.Method;
- import java.util.Arrays;
-
- import org.springframework.aop.AfterReturningAdvice;
-
- public class MyAfterReturningAdvice implements AfterReturningAdvice{
-
- @Override
- public void afterReturning(Object arg0, Method arg1, Object[] arg2, Object arg3) throws Throwable {
- //拿到目标对象的类名
- String clzName = arg3.getClass().getName();
- //当前调用的方法是
- String methodName = arg1.getName();
- //当前调用方法所传递参数
- String args = Arrays.toString(arg2);
- //方法调用后的返回值
- System.out.println("[买书返利日志]:"+clzName+"."+methodName+"这个方法被调用,传递的参数为:"+args+"目标对象方法的返回值为:"+arg0);
-
- }
-
- }
spring-context.xml配置
- <bean class="com.oyang.aop.biz.impl.BookBizImpl" id="bookBiz">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodBeforeAdivce" id="myBefore">bean>
-
- <bean class="com.oyang.aop.advice.MyAfterReturningAdvice" id="myAfter">bean>
-
- <bean class="org.springframework.aop.framework.ProxyFactoryBean" id="bookProxy">
-
- <property name="target" ref="bookBiz">property>
-
- <property name="proxyInterfaces">
- <list>
- <value>com.oyang.aop.biz.BookBizvalue>
- list>
- property>
-
- <property name="interceptorNames">
- <list>
- <value>myBeforevalue>
- <value>myAftervalue>
- list>
- property>
- bean>
org.aopalliance.intercept.MethodInterceptor
类似拦截器,会包括切入点,目标类前后都会执行代码。
MyMethodInterceptor
- package com.oyang.aop.advice;
-
- import java.lang.reflect.Method;
- import java.util.Arrays;
-
- import org.aopalliance.intercept.MethodInterceptor;
- import org.aopalliance.intercept.MethodInvocation;
-
- /**
- * 环绕通知=前置通知+后置通知
- * @author Administrator
- *
- */
- public class MyMethodInterceptor implements MethodInterceptor{
-
- @Override
- public Object invoke(MethodInvocation arg0) throws Throwable {
- //拿到目标对象的类名
- String clzName = arg0.getThis().getClass().getName();
- //当前调用的方法是
- String methodName = arg0.getMethod().getName();
- //当前调用方法所传递参数
- String args = Arrays.toString(arg0.getArguments());
- System.out.println("[环绕通知]:"+clzName+"."+methodName+"这个方法被调用,传递的参数为:"+args);
- //方法的返回值 --执行目标方法 bookBiz.buy(欧阳,完美世界,32.9d)
- Object rs = arg0.proceed();
- System.out.println("[环绕通知]:目标对象方法的返回值为:"+rs);
- return rs;
- }
-
-
-
- }
spring-context.xml配置
- <bean class="com.oyang.aop.biz.impl.BookBizImpl" id="bookBiz">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodBeforeAdivce" id="myBefore">bean>
-
- <bean class="com.oyang.aop.advice.MyAfterReturningAdvice" id="myAfter">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodInterceptor" id="myMethod">bean>
-
- <bean class="org.springframework.aop.framework.ProxyFactoryBean" id="bookProxy">
-
- <property name="target" ref="bookBiz">property>
-
- <property name="proxyInterfaces">
- <list>
- <value>com.oyang.aop.biz.BookBizvalue>
- list>
- property>
-
- <property name="interceptorNames">
- <list>
- <value>myBeforevalue>
- <value>myAftervalue>
- <value>myMethodvalue>
- list>
- property>
- bean>
org.springframework.aop.ThrowsAdvice
出现异常执行系统提示,然后进行处理。价格异常为例
MyThrowsAdvice
- package com.oyang.aop.advice;
-
- import org.springframework.aop.ThrowsAdvice;
-
- import com.oyang.aop.exception.PriceException;
- /**
- * 关于过滤通知
- * 相较于前置通知、后置通知、环绕通知有一个非常大的区别
- * 前面三大通知都需要实现其中的方法
- * 环绕通知则不需要,但是他的方法名又固定的
- * @author Administrator
- *
- */
- public class MyThrowsAdvice implements ThrowsAdvice{
-
- public void afterThrowing(PriceException p) {
- System.out.println("[异常通知]:当前价格发送异常,那么执行此处代码块!!!");
- }
-
- }
spring-context.xml配置
- <bean class="com.oyang.aop.biz.impl.BookBizImpl" id="bookBiz">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodBeforeAdivce" id="myBefore">bean>
-
- <bean class="com.oyang.aop.advice.MyAfterReturningAdvice" id="myAfter">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodInterceptor" id="myMethod">bean>
-
- <bean class="com.oyang.aop.advice.MyThrowsAdvice" id="myThrows">bean>
-
- <bean class="org.springframework.aop.framework.ProxyFactoryBean" id="bookProxy">
-
- <property name="target" ref="bookBiz">property>
-
- <property name="proxyInterfaces">
- <list>
- <value>com.oyang.aop.biz.BookBizvalue>
- list>
- property>
-
- <property name="interceptorNames">
- <list>
- <value>myBeforevalue>
- <value>myAftervalue>
- <value>myMethodvalue>
- <value>myThrowsvalue>
- list>
- property>
- bean>
org.springframework.aop.support.RegexpMethodPointcutAdvisor
处理买书返利的bug
spring-context.xml配置
- <bean class="com.oyang.aop.biz.impl.BookBizImpl" id="bookBiz">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodBeforeAdivce" id="myBefore">bean>
-
- <bean class="com.oyang.aop.advice.MyAfterReturningAdvice" id="myAfter">bean>
-
- <bean class="com.oyang.aop.advice.MyMethodInterceptor" id="myMethod">bean>
-
- <bean class="com.oyang.aop.advice.MyThrowsAdvice" id="myThrows">bean>
-
- <bean class="org.springframework.aop.support.RegexpMethodPointcutAdvisor" id="myafterPlus">
- <property name="advice" ref="myAfter">property>
- <property name="pattern" value=".*buy">property>
- bean>
-
- <bean class="org.springframework.aop.framework.ProxyFactoryBean" id="bookProxy">
-
- <property name="target" ref="bookBiz">property>
-
- <property name="proxyInterfaces">
- <list>
- <value>com.oyang.aop.biz.BookBizvalue>
- list>
- property>
-
- <property name="interceptorNames">
- <list>
- <value>myBeforevalue>
-
- <value>myafterPlusvalue>
- <value>myMethodvalue>
- <value>myThrowsvalue>
-
- list>
- property>
- bean>
OK,今日的学习就到此结束啦,如果对个位看官有帮助的话可以留下免费的赞哦(收藏或关注也行),如果文章中有什么问题或不足以及需要改正的地方可以私信博主,博主会做出改正的。个位看官,小陽在此跟大家说拜拜啦