24.12.25 AOP

• 前置通知
• 环绕通知
• 后置通知
• 最终通知
• 异常通知

API类似，只是生效的时机不一样，并且，不能保证，各个通知的顺序

try {//前置通知before();//环绕通知，内部是执行的方法around(proxy,method,args,methodProxy);//后置通知afterReturn();
} catch (Throwable e) {exception();//异常通知
}finally {after();//最终通知
}

前置通知

被访问的方法，执行之前执行的通知

先执行通知的方法，然后再执行被访问的方法本身

public void f2(JoinPoint joinPoint){
System.out.println("----------前置通知");
//被访问方法的参数
Object[] args = joinPoint.getArgs();
//被访问方法所在类的，bean对象
Object target = joinPoint.getTarget();
//被访问的方法
MethodSignature signature = (MethodSignature) joinPoint.getSignature();
Method method = signature.getMethod();
System.out.println(method.getName()+"被调用了，传入了参数："+ Arrays.toString(args)+"---所在类："+target);
}

环绕通知

public Object aroundMethod(ProceedingJoinPoint joinPoint) throws Throwable {System.out.println("==========环绕通知开始=========");//调用方法，必须写的，如果不写，目标方法不会被调用//Object o 是被执行方法的返回值Object o = joinPoint.proceed();//MethodSignature signature = (MethodSignature) joinPoint.getSignature();Method method = signature.getMethod();Object[] args = joinPoint.getArgs();//method.invoke(12);System.out.println("==========环绕通知结束========="+method.getName());return o;
}

• 配置通知

<aop:aspect ref="test1"><!--前置通知,在切入点的方法,被访问之前,执行的方法--><aop:before method="f2" pointcut-ref="q3"/><aop:around method="aroundMethod" pointcut-ref="q3"/><aop:after-throwing method="f3" pointcut-ref="q3"/><aop:after method="f4" pointcut-ref="q3"/><aop:after-returning method="f5" pointcut-ref="q3"/>
</aop:aspect>

SpringAOP原理

动态代理

注解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:context="http://www.springframework.org/schema/context"xmlns:aop="http://www.springframework.org/schema/aop"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/aophttps://www.springframework.org/schema/aop/spring-aop.xsd"
><context:component-scan base-package="com.javasm"/><!--开启AOP注解--><aop:aspectj-autoproxy/>
</beans>

//<aop:aspect ref='aspect2'>
@Component("aspect2")
@Aspect
public class TestAspect2 {//切点，标记@Pointcut("execution(* com.javasm.*.service.*.*.query*(..))")void f1(){}@Before("f1()")void before(JoinPoint joinPoint){System.out.println("注解前置通知");}@Around("f1()")Object aroundTest(ProceedingJoinPoint joinPoint) throws Throwable {System.out.println("-----环绕通知开始");Object proceed = joinPoint.proceed();System.out.println("------环绕通知结束");return proceed;}@After("f1()")void after(JoinPoint joinPoint){System.out.println("========最终通知");}//@AfterReturning("f1()")@AfterReturning(value = "f1()",returning = "msg")void afterReturn(JoinPoint joinPoint,Object msg){System.out.println("##########后置通知########返回值:"+msg);}//@AfterThrowing("f1()")@AfterThrowing(value = "f1()",throwing = "e")void afterThrowing(JoinPoint joinPoint,Throwable e){System.out.println("=========异常通知:"+e);}
}

自定义注解

自定义注解搭配AOP注解,灵活的控制方法

案例:

想在项目中记录日志

但是不是每个模块每个方法都记录

哪个方法需要记录,现在还不确定,但是要提前把业务逻辑写好

利用自定义注解,哪个方法需要增加日志,就在哪个方法上面加上自定义注解

• 自定义注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface SaveLog {//String value();
}

• 切面类

@Component
@Aspect
public class SaveLogAspect {@ResourceLogService logService;//方法执行结束之后,保存日志@AfterReturning("@annotation(com.javasm.aspect.SaveLog)")public void saveLog(JoinPoint joinPoint){String msg = "%s方法,在%s时间,被调用了,参数是%s";//方法MethodSignature signature = (MethodSignature) joinPoint.getSignature();Method method = signature.getMethod();String methodName = method.getName();//时间SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String time = simpleDateFormat.format(new Date());//参数String parameters = Arrays.toString(joinPoint.getArgs());msg = String.format(msg,methodName,time,parameters);logService.save(msg);}
}

@SaveLog

• 控制到类

案例:

统计方法运行消耗的时间

统计某一个类所有的方法

@within必须是在类级别生效

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Time {
}

@Component
@Aspect
public class TimeAspect {@Around("@within(com.javasm.aspect.Time)")public Object around(ProceedingJoinPoint joinPoint) throws Throwable {long start = System.currentTimeMillis();Object proceed = joinPoint.proceed();long time = System.currentTimeMillis() - start;String msg = "%s方法,运行消耗的时间是%s毫秒";MethodSignature signature = (MethodSignature) joinPoint.getSignature();String methodName = signature.getMethod().getName();System.out.printf(msg,methodName,time);return proceed;}
}

@Time

配置类启动

@Configuration
@ComponentScan("com.javasm")
@EnableAspectJAutoProxy//开启注解AOP
public class JavasmConfig {}

AnnotationConfigApplicationContext applicationContext =new AnnotationConfigApplicationContext(JavasmConfig.class);