1 @Override
2 public Object invoke(MethodInvocation mi) throws Throwable {
3     //终于开始做事了，调用增强器的before方法，明显是通过反射的方式调用
4     //到这里增强方法before的业务逻辑执行
5     this.advice.before(mi.getMethod(), mi.getArguments(), mi.getThis());
6     //又调用了调用MethodInvocation的proceed方法
7     return mi.proceed();
8 }

@Nullable
protected Object invokeJoinpoint() throws Throwable {
    return AopUtils.invokeJoinpointUsingReflection(this.target, this.method, this.arguments);
}

    @Nullable
public static Object invokeJoinpointUsingReflection(@Nullable Object target, Method method, Object[] args)
        throws Throwable {

    // Use reflection to invoke the method.
    try {
        ReflectionUtils.makeAccessible(method);
        //直接通过反射调用目标bean中的method
        return method.invoke(target, args);
    }
    catch (InvocationTargetException ex) {
        // Invoked method threw a checked exception.
        // We must rethrow it. The client won't see the interceptor.
        throw ex.getTargetException();
    }
    catch (IllegalArgumentException ex) {
        throw new AopInvocationException("AOP configuration seems to be invalid: tried calling method [" +
                method + "] on target [" + target + "]", ex);
    }
    catch (IllegalAccessException ex) {
        throw new AopInvocationException("Could not access method [" + method + "]", ex);
    }
}