使用 Spring AOP 从带注释的方法中获取带注释的参数值

Question

I have a program written in Java 11 with two custom annotation. One on Method level and one on Parameter level. I`m using Spring AOP to act on methods that use my Custom annotations. But I have not found a way to get the value ouf of an optional annotation that is on Parameter level.

@CustomAnnotation
public void myMethod(@CustomValue String param1, int param2) {
    ...
}

@AfterReturning(value = "@annotation(customAnnotation)", argNames = "customAnnotation, jp")
public void afterReturning(JoinPoint jp, CustomAnnotation customAnnotation) {
    ...
}

The program works well with my @CustomAnnotation, but I have problems to get the value out of parameters that is annotated with @CustomValue. @CustomValue is useless if the method is not annotated with @CustomAnnotation. And the number of parameters that can be annotated with @CustomValue is 0 or more.

How can I get the values from the parameters that is annotated with @CustomValue on a method that is annotated with @CustomAnnotation?

Answer 1

@AfterReturning(value = "@annotation(CustomAnnotation)", argNames = "customAnnotation, jp")
public void afterReturning(JoinPoint jp, CustomAnnotation customAnnotation) {
     CustomAnnotation annotation = customAnnotation;
    List<Parameter> parameterList = new ArrayList<>();

        if (jp.getSignature() instanceof MethodSignature) {
            MethodSignature signature =
                    (MethodSignature) jp.getSignature();
            Method method = signature.getMethod();
            anno = method.getAnnotation(CustomAnnotation.class);

            Parameter[] params = method.getParameters();
            for (Parameter param : params) {
                try {
                    if(param.getAnnotation(CustomValue.class) !=null){
                       parameterList.add(param);
                   }
                } catch (Exception e) {
                    //do nothing
                }
            }
        }
    }

You should now get the list of parameters annotated with @CustomValue. This exact code may not work while copy-paste, but you should get the idea.

Answer 2

Maybe there is a better way, but I solved this by using following:

@AfterReturning(value = "@annotation(customAnnotation)", argNames = "customAnnotation, jp")
public void afterReturning(JoinPoint jp, CustomAnnotation customAnnotation) {
    MethodSignature signature = (MethodSignature) jp.getSignature();
    Parameter[] parameters = signature.getMethod().getParameters();
    Object[] args = jp.getArgs();

    for (int i = 0; i < args.length; ++i) {
        if (parameters[i].isAnnotationPresent(CustomValue.class)) {
            Object paramValue = args[i];
        }
    }
}