Spring框架——AOP前置、后置、环绕、异常通知

柔光的暖阳◎ 2022-05-25 06:45 336阅读 0赞

@Aspect
    @Component
    public class LoggingAspect {
    
        /**
         * 在 com.spring.aop.Impl.ArithmeticCalculator 接口的每一个实现类的每一个方法开始之前执行一段代码.
         */
        @Before("execution(* com.spring.aop.Impl.*.*(..))")
        public void beforeMethod(JoinPoint joinPoint){
            String methodName = joinPoint.getSignature().getName();
            Object[] args = joinPoint.getArgs();
            System.out.println("The Method " + methodName + " begins with " + Arrays.asList(args));
        }
    
        /**
         * 在方法执行之后执行的代码. 无论该方法是否出现异常
         */
        @After("execution(* com.spring.aop.Impl.*.*(..))")
        public void afterMethod(JoinPoint joinPoint){
            String methodName = joinPoint.getSignature().getName();
            System.out.println("The Method " + methodName + " ends");
        }
    
        /**
         * 在方法正常结束后执行的代码
         * 返回通知是可以访问到方法的返回值的
         */
        //返回通知
        @AfterReturning(value="execution(* com.spring.aop.Impl.*.*(..))",returning="result")
        public void afterReturning(JoinPoint joinPoint,Object result){
            String methodName = joinPoint.getSignature().getName();
            System.out.println("The Method " + methodName + " ends with " + result);
        }
    
        /**
         * 在目标方法出现异常时, 会执行的代码.
         * 可以访问到异常对象, 且可以指定再出现特定异常时再执行通知代码
         */
        @AfterThrowing(value="execution(* com.spring.aop.Impl.*.*(..))", throwing="ex")
        public void afterThrowing(JoinPoint joinPoint, Exception ex){
            String methodName = joinPoint.getSignature().getName();
            System.out.println("The Method " + methodName + " occurs excetion: " + ex);
        }
    
        /**
         * 环绕通知需要携带 ProceedingJoinPoint 类型的参数.
         * 环绕通知类似于动态代理的全过程: ProceedingJoinPoint 类型的参数可以决定是否执行目标方法
         * 且环绕通知必须有返回值, 返回值即为目标方法的返回值.
         */
        @Around("execution(* com.spring.aop.Impl.*.*(..))")
        public Object aroundMethod(ProceedingJoinPoint joinPoint){
    
            Object result = null;
            String methodName = joinPoint.getSignature().getName();
    
            //执行目标方法
            try {
                //前置通知
                System.out.println("The method " + methodName + " begins with " + Arrays.asList(joinPoint.getArgs()));
                //执行目标方法
                result = joinPoint.proceed();
                //后置通知
                System.out.println("The method " + methodName + "  ends with " + result);
            } catch (Throwable e) {
                //异常通知
                System.out.println("The method " + methodName + "  occurs exception: " + e);
                throw new RuntimeException(e);
            }
            //后置通知
            System.out.println("The method " + methodName + " ends");
            return result;
        }
    
    }

package com.abc.advice; import java.util.Arrays; import org.aspectj.lang.JoinPoint; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.AfterReturning; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; @Aspect public class AdviceTest {     @Around("execution(* com.abc.service.*.many*(..))")     public Object process(ProceedingJoinPoint point) throws Throwable {         System.out.println("@Around：执行目标方法之前...");         //访问目标方法的参数：         Object[] args = point.getArgs();         if (args != null && args.length > 0 && args[0].getClass() == String.class) {             args[0] = "改变后的参数1";         }         //用改变后的参数执行目标方法         Object returnValue = point.proceed(args);         System.out.println("@Around：执行目标方法之后...");         System.out.println("@Around：被织入的目标对象为：" + point.getTarget());         return "原返回值：" + returnValue + "，这是返回结果的后缀";     }          @Before("execution(* com.abc.service.*.many*(..))")     public void permissionCheck(JoinPoint point) {         System.out.println("@Before：模拟权限检查...");         System.out.println("@Before：目标方法为：" +                  point.getSignature().getDeclaringTypeName() +                  "." + point.getSignature().getName());         System.out.println("@Before：参数为：" + Arrays.toString(point.getArgs()));         System.out.println("@Before：被织入的目标对象为：" + point.getTarget());     }          @AfterReturning(pointcut="execution(* com.abc.service.*.many*(..))",          returning="returnValue")     public void log(JoinPoint point, Object returnValue) {         System.out.println("@AfterReturning：模拟日志记录功能...");         System.out.println("@AfterReturning：目标方法为：" +                  point.getSignature().getDeclaringTypeName() +                  "." + point.getSignature().getName());         System.out.println("@AfterReturning：参数为：" +                  Arrays.toString(point.getArgs()));         System.out.println("@AfterReturning：返回值为：" + returnValue);         System.out.println("@AfterReturning：被织入的目标对象为：" + point.getTarget());              }          @After("execution(* com.abc.service.*.many*(..))")     public void releaseResource(JoinPoint point) {         System.out.println("@After：模拟释放资源...");         System.out.println("@After：目标方法为：" +                  point.getSignature().getDeclaringTypeName() +                  "." + point.getSignature().getName());         System.out.println("@After：参数为：" + Arrays.toString(point.getArgs()));         System.out.println("@After：被织入的目标对象为：" + point.getTarget());     } }

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[70]: /images/20220525/1f9d9643e16240ce9e42ee60bea6c184.png