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How to retrieve custom annotation fields?

I would like to implement a custom annotation that could be applied to a class (once inside an app), to enable a feature (Access to remote resources). If this annotation is placed on any config class, it will set the access for the whole app. So far it isn't that hard (see example below), but I want to include some definition fields in the #interface that will be used in the access establishing process.
As an example, Spring has something very similar: #EnableJpaRepositories. Access is enabled to the DB, with parameters in the annotation containing definitions. For example: #EnableJpaRepositories(bootstrapMode = BootstrapMode.DEFERRED)
So far, I have:
To create only the access I'm using something like that:
#Target(ElementType.TYPE)
#Retention(RetentionPolicy.RUNTIME)
#Import(AccessHandlerConfiguration.class)
public #interface EnableAccessHandlerAutoconfigure {
String name() default "";
}
Using it:
#EnableAccessHandlerAutoconfigure{name="yoni"}
#Configuration
public class config {}
AccessHandlerConfiguration is a configuration class that contains beans that establish the connection.
The problem I'm having is that I don't know how to retrieve the field name's value. What should I do?

Retrieving the value may be accomplished as follows:
this.getClass().getAnnotation(EnableAccessHandlerAutoconfigure.class).name()
To expand on my comment with an actual example configuration class that uses this:
#EnableAccessHandlerAutoconfigure(name="yoni")
#Configuration
public class SomeConfiguration {
#Bean
SomeBean makeSomeBean() {
return new SomeBean(this.getClass().getAnnotation(EnableAccessHandlerAutoconfigure.class).name());
}
}
This is how you get the value of name, as to what you are going to do next, that depends on you.

After a long research, I found a way: There is a method in Spring's ApplicationContext that retrieves bean names according to their annotations getBeanNamesForAnnotation, then get the annotation itself findAnnotationOnBean, and then simply use the field getter.
#Configuration
public class AccessHandlerConfiguration {
private final ApplicationContext applicationContext;
public AccessHandlerConfiguration(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
String[] beansWithTheAnnotation = applicationContext.getBeanNamesForAnnotation(EnableRabbitAutoconfigure.class);
for (String beanName : beansWithTheAnnotation) {
EnableRabbitAutoconfigure annotationOnBean = applicationContext.findAnnotationOnBean(beanName, EnableRabbitAutoconfigure.class);
System.out.println("**********" + beanName + "*********************" + annotationOnBean.name() + "*******************");
}
}
}
Results:
**********config*********************yoni*******************

Spring injection with Java's Optional

When trying to inject an Optional<T>, Spring never calls my bean, and instead injects an Optional.empty().
Here is some sample code:
#Configuration
public class Initialize {
#Value("optionalValue")
private String testString;
#Bean (name = "getOptionalString")
public Optional<String> getOptionalString() {
return Optional.of(this.testString); //breakpoint put here, is never called
}
}
#Component
public class Test {
public Test(#Qualifier("getOptionalString") Optional<String> optional) {
// optional's value is Optional.empty() here
}
I noticed that (by putting a breakpoint) the #Bean is never called. If I were to remove the Optional<String>, and simply return a String, then it works!
I know Spring has its own optional dependency but I am perplexed as to why this doesn't work (whatever I read online says it should), and I also don't understand how it initialized it to Optional.empty()?

The documentation says:
you can express the non-required nature of a particular dependency through Java 8’s java.util.Optional, as the following example shows:
public class SimpleMovieLister {
#Autowired
public void setMovieFinder(Optional<MovieFinder> movieFinder) {
...
}
}
So using Optional as the type of a bean is not a good idea.

Spring Managed Custom Validator not being used from endpoint

I've been at this for a while, but I have a Spring managed custom validator that looks like the below, I have some print statements in there which I'll get to later
#Component
public class BulkUpdateValidator implements ConstraintValidator<ValidBulkUpdate, BulkUpdate> {
#Autowired
ObjectMapper mapper;
public BulkUpdateValidator(){
System.out.println(this.toString());
}
#PostConstruct
public void post(){
System.out.println(mapper);
System.out.println(this.toString());
}
public boolean isValid(BulkUpdate update, ConstraintValidatorContext context){
System.out.println(this.toString());
System.out.println(mapper);
}
... other validator methods ...
}
My controller method: (NOTE: my controller class is annotated with #Validated at the top)
#RequestMapping(...)
public #ResponseBody RestResponse bulkUpdate(#Valid #ValidBulkUpdate Bulkupdate bulkUpdate){
... stuff here ...
}
My Bean:
public class BulkUpdate {
#NotEmpty
public List<String> recordIds;
#NotEmpty
#Valid
public List<FieldUpdate> updates;
.... getters and setters ....
}
Here's my problem, when I execute the endpoint it get a NullPointerException when I attempt to use the autowired mapper. The output from the print statements I posted above are quite telling. In both the constructor and the #PostConstruct sections I get the same Object ID for the validator and I also get an ID for the mapper. However, once isValid is called, it prints out a different Object ID. I know the spring managed validator is being created, but it's not being used.
Furthermore, I've tried to remove the #ValidBulkUpdate annotation from the REST endpoint and put it inside a wrapper object, thinking that maybe #Valid was necessary to get spring to take over, like below:
public #ResponseBody RestResponse bulkUpdate(#Valid BulkupdateWrapper bulkUpdate){
... stuff here ...
}
And wrapper
public class BulkUpdateWrapper {
#ValidBulkUpdate
private BulkUpdate update;
.... getter and setter ....
}
This leaves me with a whole new error which is even weirder:
"JSR-303 validated property 'update.org.hibernate.validator.internal.engine.ConstraintViolationImpl' does not have a corresponding accessor"
I'm not sure where to turn, hopefully someone has an idea. Either how to get it to use the Spring managed validator, or how to remove that vague error when I use the object wrapper;
What's worse, is I have MockMvc based Integration tests for this that run flawlessly, this only happens when I deploy it.
UPDATE
So I kept my wrapper and changed #Valid to #Validated and now my error is the following: "NotReadablePropertyException: Bean property 'update.field' does not have a corresponding accessor for Spring data binding"
Fun fact, there is no property called "field"

Filterregisteration Bean and injection of a collection #Value

We have a configuration class:
public class FilterConfigBase {
#Bean
public FilterRegisterationBean
corsFilter(#value("${client.ip.headers:}") List<String>
clientIpHeaders)
{
....
...
...
}
}
Application.properties:
client.ip.headers=A,B,C
We have a DefaultConversion service bean (which has StringToCollectionConverter)
In FilterConfigBase (Which contains only FIlterRegisterationBean), #Value annotation is not calling the StringToCollectionConverter class instead the conversion result is:
clientIpHeaders[0]="A,B,C"
Whereas in other configuration classes, #Value annotation is able to resolve the property, It calls the StringToCollectionConverter and the values are properly populated.
clientIpHeaders.get(0)="A"
clientIpHeaders.get(1)="B"
clientIpHeaders.get(2)="C"
For more details:
https://github.com/spring-projects/spring-boot/issues/11585

You can try to add a bit of EL there to split into list:
#Bean
public FilterRegisterationBean
corsFilter(#value("#{'${client.ip.headers:}'.split(',')}") List<String>
clientIpHeaders)

Java Spring #Valid on a method call [duplicate]

Hej,
I want to use the #Validated(group=Foo.class) annotation to validate an argument before executing a method like following:
public void doFoo(Foo #Validated(groups=Foo.class) foo){}
When i put this method in the Controller of my Spring application, the #Validated is executed and throws an error when the Foo object is not valid. However if I put the same thing in a method in the Service layer of my application, the validation is not executed and the method just runs even when the Foo object isn't valid.
Can't you use the #Validated annotation in the service layer ? Or do I have to do configure something extra to make it work ?
Update:
I have added the following two beans to my service.xml:
<bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean"/>
<bean class="org.springframework.validation.beanvalidation.MethodValidationPostProcessor"/>
and replaced the #Validate with #Null like so:
public void doFoo(Foo #Null(groups=Foo.class) foo){}
I know it is a pretty silly annotation to do but I wanted to check that if I call the method now and passing null it would throw an violation exception which it does. So why does it execute the #Null annotation and not the #Validate annotation ? I know one is from javax.validation and the other is from Spring but I do not think that has anything to do with it ?

In the eyes of a Spring MVC stack, there is no such thing as a service layer. The reason it works for #Controller class handler methods is that Spring uses a special HandlerMethodArgumentResolver called ModelAttributeMethodProcessor which performs validation before resolving the argument to use in your handler method.
The service layer, as we call it, is just a plain bean with no additional behavior added to it from the MVC (DispatcherServlet) stack. As such you cannot expect any validation from Spring. You need to roll your own, probably with AOP.
With MethodValidationPostProcessor, take a look at the javadoc
Applicable methods have JSR-303 constraint annotations on their
parameters and/or on their return value (in the latter case specified
at the method level, typically as inline annotation).
Validation groups can be specified through Spring's Validated
annotation at the type level of the containing target class, applying
to all public service methods of that class. By default, JSR-303 will
validate against its default group only.
The #Validated annotation is only used to specify a validation group, it doesn't itself force any validation. You need to use one of the javax.validation annotations like #Null or #Valid. Remember that you can use as many annotations as you would like on a method parameter.

As a side note on Spring Validation for methods:
Since Spring uses interceptors in its approach, the validation itself is only performed when you're talking to a Bean's method:
When talking to an instance of this bean through the Spring or JSR-303 Validator interfaces, you'll be talking to the default Validator of the underlying ValidatorFactory. This is very convenient in that you don't have to perform yet another call on the factory, assuming that you will almost always use the default Validator anyway.
This is important because if you're trying to implement a validation in such a way for method calls within the class, it won't work. E.g.:
#Autowired
WannaValidate service;
//...
service.callMeOutside(new Form);
#Service
public class WannaValidate {
/* Spring Validation will work fine when executed from outside, as above */
#Validated
public void callMeOutside(#Valid Form form) {
AnotherForm anotherForm = new AnotherForm(form);
callMeInside(anotherForm);
}
/* Spring Validation won't work for AnotherForm if executed from inner method */
#Validated
public void callMeInside(#Valid AnotherForm form) {
// stuff
}
}
Hope someone finds this helpful. Tested with Spring 4.3, so things might be different for other versions.

#pgiecek You don't need to create a new Annotation. You can use:
#Validated
public class MyClass {
#Validated({Group1.class})
public myMethod1(#Valid Foo foo) { ... }
#Validated({Group2.class})
public myMethod2(#Valid Foo foo) { ... }
...
}

Be careful with rubensa's approach.
This only works when you declare #Valid as the only annotation. When you combine it with other annotations like #NotNull everything except the #Valid will be ignored.
The following will not work and the #NotNull will be ignored:
#Validated
public class MyClass {
#Validated(Group1.class)
public void myMethod1(#NotNull #Valid Foo foo) { ... }
#Validated(Group2.class)
public void myMethod2(#NotNull #Valid Foo foo) { ... }
}
In combination with other annotations you need to declare the javax.validation.groups.Default Group as well, like this:
#Validated
public class MyClass {
#Validated({ Default.class, Group1.class })
public void myMethod1(#NotNull #Valid Foo foo) { ... }
#Validated({ Default.class, Group2.class })
public void myMethod2(#NotNull #Valid Foo foo) { ... }
}

As stated above to specify validation groups is possible only through #Validated annotation at class level. However, it is not very convenient since sometimes you have a class containing several methods with the same entity as a parameter but each of which requiring different subset of properties to validate. It was also my case and below you can find several steps to take to solve it.
1) Implement custom annotation that enables to specify validation groups at method level in addition to groups specified through #Validated at class level.
#Target({ElementType.METHOD})
#Retention(RetentionPolicy.RUNTIME)
#Documented
public #interface ValidatedGroups {
Class<?>[] value() default {};
}
2) Extend MethodValidationInterceptor and override determineValidationGroups method as follows.
#Override
protected Class<?>[] determineValidationGroups(MethodInvocation invocation) {
final Class<?>[] classLevelGroups = super.determineValidationGroups(invocation);
final ValidatedGroups validatedGroups = AnnotationUtils.findAnnotation(
invocation.getMethod(), ValidatedGroups.class);
final Class<?>[] methodLevelGroups = validatedGroups != null ? validatedGroups.value() : new Class<?>[0];
if (methodLevelGroups.length == 0) {
return classLevelGroups;
}
final int newLength = classLevelGroups.length + methodLevelGroups.length;
final Class<?>[] mergedGroups = Arrays.copyOf(classLevelGroups, newLength);
System.arraycopy(methodLevelGroups, 0, mergedGroups, classLevelGroups.length, methodLevelGroups.length);
return mergedGroups;
}
3) Implement your own MethodValidationPostProcessor (just copy the Spring one) and in the method afterPropertiesSet use validation interceptor implemented in step 2.
#Override
public void afterPropertiesSet() throws Exception {
Pointcut pointcut = new AnnotationMatchingPointcut(Validated.class, true);
Advice advice = (this.validator != null ? new ValidatedGroupsAwareMethodValidationInterceptor(this.validator) :
new ValidatedGroupsAwareMethodValidationInterceptor());
this.advisor = new DefaultPointcutAdvisor(pointcut, advice);
}
4) Register your validation post processor instead of Spring one.
<bean class="my.package.ValidatedGroupsAwareMethodValidationPostProcessor"/>
That's it. Now you can use it as follows.
#Validated(groups = Group1.class)
public class MyClass {
#ValidatedGroups(Group2.class)
public myMethod1(Foo foo) { ... }
public myMethod2(Foo foo) { ... }
...
}