AOP（Aspect Orient Programming），我们一般称为面向方面（切面）编程，作为面向对象的一种补充，用于处理系统中分布于各个模块的横切关注点，比如事务管理、日志、缓存等等。AOP实现的关键在于AOP框架自动创建的AOP代理，AOP代理主要分为静态代理和动态代理，静态代理的代表为AspectJ；而动态代理则以Spring AOP为代表。
AOP配置示例：
需要的包：aspectjweaver-1.8.4.jar
数据访问层：
package com.hanqi.dao;public class AppuserDao {public int deleteUser(int ids) {System.out.println(ids +"被删除");yichang();//抛出一个异常return 1;}public void yichang() {throw new RuntimeException("出现错误！");}
}
切面代理层：
package com.hanqi.util;public class LogginProxy {public void beforeMethod() {System.out.println("方法之前被调用！");}public void afterMethod() {System.out.println("方法之后被调用！");}public void returnMethod() {System.out.println("返回结果时被调用！");}public void throwMethod() {System.out.println("抛出异常时被调用！");}/*public void aroundMethod() {System.out.println("方法被调用");}*/
}
spring.xml配置AOP
?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.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd"><bean id="logginProxy" class="com.hanqi.util.LogginProxy"></bean><bean id="appuserdao" class="com.hanqi.dao.AppuserDao"></bean><aop:config><!-- 配置切点 --><aop:pointcutexpression="execution(* com.hanqi.dao.*.*(..))" id="aoppointcut" /><!--execution:执行，这句意为在执行com.hanqi.dao下的所有类时都会执行切面类--><!-- 指明切面类 --><aop:aspect ref="logginProxy"><aop:before method="beforeMethod" pointcut-ref="aoppointcut"/><aop:after method="afterMethod" pointcut-ref="aoppointcut"/><aop:after-returning method="returnMethod" pointcut-ref="aoppointcut"/><aop:after-throwing method="throwMethod" pointcut-ref="aoppointcut"/> </aop:aspect></aop:config>
</beans>
JUnit Test测试：
package com.hanqi.util;import static org.junit.jupiter.api.Assertions.*;import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;import com.hanqi.dao.AppuserDao;class JUnittest {private ClassPathXmlApplicationContext c;private AppuserDao appuserdao;@BeforeEachvoid setUp() throws Exception {c = new ClassPathXmlApplicationContext("spring.xml");appuserdao = c.getBean(AppuserDao.class);}@AfterEachvoid tearDown() throws Exception {c.close();}@Testvoid test() {appuserdao.deleteUser(55);}}
打印结果：
使用注解配置AOP
spring.xml配置：
<?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.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd"><context:component-scan base-package="com.hanqi"></context:component-scan><!--配置扫描器-->
</beans>
数据访问层：
package com.hanqi.dao;import org.springframework.stereotype.Repository;@Repository//加到spring容器中，id名默认为类名首字母小写
public class AppuserDao {public int deleteUser(int ids) {System.out.println(ids +"被删除");yichang();return 1;}public void yichang() {throw new RuntimeException("出现错误！");}
}
AppuserService类：
package com.hanqi.service;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Repository;import com.hanqi.dao.AppuserDao;
@Repository
public class AppuserService {@Autowired//从spring容器中将该类自动放到当前类中的成员变量中，默认的装配类型时byType//@Qualifier("dao")该注解可将bean中id="dao"的类装配到该成员变量中，用于区分当类型相同时；private AppuserDao appuserDao;public int deleteUser(int ids) {return appuserDao.deleteUser(ids);}
}
代理类：
package com.hanqi.util;import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.stereotype.Repository;@Repository//加到spring容器中，id名为类名首字母小写
@Aspect//声明当前类为切面类
@EnableAspectJAutoProxy//自动代理
public class LogginProxy {@Before("execution(* com.hanqi.dao.*.*(..))")//声明切点public void beforeMethod() {System.out.println("方法之前被调用！");}@After("execution(* com.hanqi.dao.*.*(..))")public void afterMethod() {System.out.println("方法之后被调用！");}@AfterReturning("execution(* com.hanqi.dao.*.*(..))")public void returnMethod() {System.out.println("返回结果时被调用！");}@AfterThrowing("execution(* com.hanqi.dao.*.*(..))")public void throwMethod() {System.out.println("抛出异常时被调用！");}/*public void aroundMethod() {System.out.println("方法被调用");}*/
}
测试类：
package com.hanqi.util;import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;import com.hanqi.dao.AppuserDao;
import com.hanqi.service.AppuserService;class JUnittest {private ClassPathXmlApplicationContext c;private AppuserDao appuserdao;private AppuserService appuserService;@BeforeEachvoid setUp() throws Exception {c = new ClassPathXmlApplicationContext("spring.xml");//appuserdao = c.getBean(AppuserDao.class);appuserService = c.getBean(AppuserService.class);}@AfterEachvoid tearDown() throws Exception {c.close();}@Testvoid test() {//appuserdao.deleteUser(55);appuserService.deleteUser(66);}}
