My use case:
I will have a lot of #PreAuthorize annotation in the form #PreAuthorize("hasAuthority('RESPECT_MY_AUTHORITY')").
I'd like to create a meta-annotation #HasAuthority which takes the authority as a value and pass it to #PreAuthorize("hasAuthority(<value>)").
It feels like it's not possible. The closest I get to what I want is something like the #AliasFor annotation. but the problem is that I can't add anything to the value I'll get in #HasAuthority. So I would have to repeat the hasAuthority part everytime.
#Target(ElementType.METHOD)
#Retention(RetentionPolicy.RUNTIME)
#PreAuthorize("hasAuthority('RESPECT_MY_AUTHORITY')")
public #interface HasAuthority {
#AliasFor(annotation = PreAuthorize.class, attribute = "value")
String value();
}
I'd like something like:
#Target(ElementType.METHOD)
#Retention(RetentionPolicy.RUNTIME)
#PreAuthorize("hasAuthority(#value)")
public #interface HasAuthority {
String value();
}
Any idea how I could do that, or if it's possible at all?
Related
I'm new on Hystrix, I'm just adding it to my project, but I'd like to know whether I can create a custom annotation "HystrixDefaultTimeoutProperty" that extends the HystrixProperty, so each time I want to use a default value for the timeout I can use that custom annotation instead of using:
#HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "5000")
Thanks in advance!
No, it is not possible, If you were to look at the source code of HystrixCommand and #HystrixProperty
#Target({ElementType.METHOD})
#Retention(RetentionPolicy.RUNTIME)
#Inherited
#Documented
public #interface HystrixCommand {
.....
}
and
#Target({ElementType.METHOD})
#Retention(RetentionPolicy.RUNTIME)
#Documented
public #interface HystrixProperty {
.....
}
Both of these annotations has
#Target({ElementType.METHOD})
which implies you can use these annotations only on Methods
recently I came across a method declaration in the following format:
#GET
#Path("/foo")
public #NotNull #Valid String foo()
{
...
}
I have problem understanding what the two annotation #NotNull and #Valid mean. Do they have the same effect if they were declared on top of the method declaration like this?
#GET
#Path("/foo")
#NotNull
#Valid
public String foo()
{
...
}
And it seems that if I have the #Valid annotation on, accessing other endpoints in the same class as foo will also trigger the execution of foo().
Could some one share some opinions?
Thanks in advance.
Do they have the same effect if they were declared on top of the method declaration like this?
YES
Accessing other endpoints should not execute foo() unless foo is called somewhere in your code.
#Valid annotation will execute validation on the return value.
I'm using Spring AOP to intercept a method execution.
I have an interface that looks like the following:
public interface MyAwesomeService {
public Response doThings(int id, #AwesomeAnnotation SomeClass instance);
}
Here is the implementation of the interface:
public class MyAwesomeServiceImpl implements MyAwesomeService {
public Response doThings(int id, SomeClass instance) {
// do something.
}
}
Now i would like any method which has a parameter annotated with #AwesomeAnnotation should be captured by Spring AOP.
So I wrote the following aspect which works.
#Aspect
#Component
public class MyAwesomeAspect {
#Around("myPointcut()")
public Object doAwesomeStuff(final ProceedingJoinPoint proceedingJoinPoint) {
final MethodSignature methodSignature = (MethodSignature) proceedingJoinPoint.getSignature();
Annotation[][] annotationMatrix = methodSignature.getMethod().getParameterAnnotations();
// annotationMatrix is empty.
}
#Pointcut("execution(public * *(.., #package.AwesomeAnnotation (package.SomeClass), ..))")
public void myPointcut() {}
}
However when I try to find the parameter annotations I don't get any annotations back. As mentioned above, the annotationMatrix is empty.
So here are my questions:
Why is the annotationMatrix empty? Probably because parameter annotations are not inherited from an interface.
Why I'm able to capture the method execution. Since Spring AOP is able match the pointcut, Spring somehow is able to see the method's parameter annotations but when I try to see that using methodSignature.getMethod().getParameterAnnotations() it doesn't work.
I also faced this issue with one of my parameter annotations. I was able to fix the same by making sure that the parameter annotation definition had RetentionPolicy as RUNTIME and Target as PARAMETER
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.PARAMETER)
public #interface Param {
public String name();
}
The answers to your questions:
Parameter annotations are not inherited from interfaces to implementing methods. In fact, annotations are almost never inherited, only from class (not interface!) to subclass if the annotation type itself is annotated by #Inherited, see JDK API documentation.
Update: Because I have answered this question several times before, I have just documented the problem and also a workaround in Emulate annotation inheritance for interfaces and methods with AspectJ.
Because during compile or weave time AspectJ can match your pointcut against the interface method and thus sees the annotation.
You can fix the situation by adding the annotation to the parameter in your interface implementation, e.g. like this:
#Override
public Response doThings(int id, #AwesomeAnnotation SomeClass instance) {
// ...
}
Then with an aspect like this...
#Aspect
#Component
public class MyAwesomeAspect {
#Pointcut("execution(public * *..MyAwesomeService.*(*, #*..AwesomeAnnotation (*), ..)) && args(*, instance, ..)")
static void myPointcut(SomeClass instance) {}
#Around("myPointcut(instance)")
public Object doAwesomeStuff(Object instance, ProceedingJoinPoint proceedingJoinPoint) {
System.out.println(proceedingJoinPoint);
System.out.println(" instance = " + instance);
MethodSignature methodSignature = (MethodSignature) proceedingJoinPoint.getSignature();
Annotation[][] annotationMatrix = methodSignature.getMethod().getParameterAnnotations();
for (Annotation[] annotations : annotationMatrix) {
for (Annotation annotation : annotations) {
System.out.println(" annotation = " + annotation);
}
}
return proceedingJoinPoint.proceed();
}
}
... you get a console log similar to this:
execution(Response de.scrum_master.app.MyAwesomeServiceImpl.doThings(int, SomeClass))
instance = de.scrum_master.app.SomeClass#23fc625e
annotation = #de.scrum_master.app.AwesomeAnnotation()
I read many question in this forum but nothing works.
public #interface MyAnnotation {
String value() default "";
Class[] exceptionList;
}
#MyAnnotation(value="hello", exceptionList={TimeOutException.class})
public void method() {}
#Aspect
public class MyAspect {
#Around("#annotation(MyAnnotation)")
public Object handle(ProceedingJoinPoint joinPoint, MyAnnotation myAnnotation) {
System.out.println(myAnnotation.exceptionList); // should print out TimeOutException
}
}
How can I get the value and the exceptionList of the #MyAnnotation while executing the advice?
I'm using Spring 4.0.6, AspectJ 1.7.4
The solution for this is making sure the advice method's parameter name match the parameter name in AspectJ expression. In my case, the advice method should look like this:
#Aspect
public class MyAspect {
#Around("#annotation(myAnnotation)")
public Object handle(ProceedingJoinPoint joinPoint, MyAnnotation myAnnotation) {
System.out.println(myAnnotation.exceptionList); // should print out TimeOutException
}
}
You are already almost there. Probably.
You are using the correct way to retrieve the annotation, so you have the values available.
Your problem - if I interpret the very minimalistic problem description(!) you only provide via the comment in your code snippet(!) correctly - is the (wrong) assumption that sticking an array of the type Class into System.out.println() will print out the names of the Classes it contains. It does not. Instead it prints information about the reference:
[Ljava.lang.Class;#15db9742
If you want the names of the Classes, you will have to iterate over the elements of that array and use .getName(), .getSimpleName() or one of the other name providing methods of Class.
Further information on how to print elements of an array is here:
What's the simplest way to print a Java array?
Granted, this whole answer could be entirely besides the point if the problem is that you are getting null values from the annotation fields. But since you have not provided an adequate problem description ("nothing works" is not a problem description!), we can only guess at what your problem is.
I would like my uiBinder to use a ClientBundle which will provide some runtime customized labels. Kind of a TextResource but not from a text file !
I tried with GwtCreateResource but from the DevGuide it seems like it's not possible. Am I right ? (create() and name() are the only methods available)
What I would like to achieve is something like this:
client bundle:
public interface MyWidgetResources extends ClientBundle {
GwtCreateResource<WidgetLabels> labels();
#Source("lol.css")
CssResource style();
}
labels class:
public final class MyWidgetLabels {
public String title() {
return load("mywidget-title");
}
public String banner() {
return load("mywidget-banner");
}
private String load(String key) {
// load from external..
}
}
uiBinder:
<ui:with type="com.package.MyWidgetResources" field="res"/>
<gwt:SimplePanel>
<gwt:Label text="{res.labels.title}"></gwt:Label>
<gwt:Label text="{res.labels.banner}"></gwt:Label>
</gwt:SimplePanel>
My code looks like this already but res.label.title does not work because GwtCreateResource can only serve as class instantiator (res.labels.create().title()).
Is there a solution for me ? Maybe with a custom ResourceGenerator ?
As long as MyWidgetLabels can be created by GWT.create, you can put anything you want into that type, and you can make it behave however you'd like. You will need the create reference in your uibinder as you suggested at the end of the post to actually build the object, so your lines will look about like this:
<gwt:Label text="{res.labels.create.title}"></gwt:Label>
Each . separated piece (except the first, which is a ui:field/#UiField) is a no-arg method to be called - you declared labels() in MyWidgetResources, create() already existed in GwtCreateResource, and you created title() in your own MyWidgetLabels type.
Since that first piece is a ui:field/#UiField, you could have another that references res.labels.create as something like labels so that later you could instead say:
<gwt:Label text="{labels.title}"></gwt:Label>
Finally, yes, you could build your own ResourceGenerator which would enable you to do whatever you wanted to emit the type in question, as long as you extended the ResourcePrototype type and had a getName() method.