Spring框架——AOP前置、后置、环绕、异常通知

@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;
    }

}