I have following code which uses functional style to define two functions for kafka topics
#Bean
public Function<KStream<String, CloudEvent<ClassA>>, KStream<String, CloudEvent<ClassB>>> method1() {
....... //lambda
}
#Bean
public Function<KStream<String, CloudEvent<ClassB>>, KStream<String, CloudEvent<ClassC>>> method2() {
...... //lambda
}
For these two functions I define serdes so
#Bean
public Serde<CloudEventMessage<ClassA>> classASerde(ObjectMapper mapper, Validator validator) {
return StreamsSerdes.classASerde(mapper,validator);
}
#Bean
public Serde<CloudEventMessage<ClassB>> classBSerde(ObjectMapper mapper, Validator validator) {
return StreamsSerdes.classBSerde(mapper,validator);
}
This construction doesn't work as at runtime spring tries to deserialize CloudEvent<ClassB> with Serde of CloutEvent<ClassA>. Is there someway to give hint to use the correct serde for method1 and method2 ?
Secondly I could bypass the above issues by mentioning Serdes in application.properties
spring.application.cloud.stream.kafka.streams.bindings.method1-in-0.consumer.valueSerde=package.serde.StreamsSerdes$ClassASerde
spring.application.cloud.stream.kafka.streams.bindings.method2-in-0.consumer.valueSerde=package.serde.StreamsSerdes$ClassBSerde
However now I get other issues as these Serde classes don't have default constructor. I do need ObjectMapper, Validator from Spring to inject beans (#Service) to perfrom converstions/validations during deserialization.
Has anyone come across similar issues or perhaps have ideas how to resolve them ?
Thanks
I think it is a gap that the nested generics are not working right now in the binder. Do you mind creating an issue in the repository and linking this thread?
As to the second issue that you are running into when providing properties in application.properties, you can try using a workaround. The Serde interface has a configure method that takes a map.
default void configure(Map<String, ?> configs, boolean isKey) {
// intentionally left blank
}
Override this method in your Serde implementation and set those bean objects under some keys.
ObjectMapper mapper;
Validator validator;
#Override
public void configure(Map<String, ?> configs, boolean isKey) {
this.mapper = (ObjectMapper) configs.get("mapper.key");
this.validator = (Validator) configs.get("validator.key");
}
You need to remove accessing them from the constructor and use those fields directly for deserialization and serialization.
Then you provide this bean in your application to populate the map:
#Bean
public StreamsBuilderFactoryBeanCustomizer streamsBuilderFactoryBeanCustomizer(ObjectMapper mapper, Validator validator) {
return factoryBean -> {
factoryBean.getStreamsConfiguration().put("mappeer.key", mapper);
factoryBean.getStreamsConfiguration().put("validator.key", validator);
};
}
I haven't tried this code in an application, but it is something that you can try and see if it works with your code.
Related
Given I have a factory class responsible for constructing instances of a certain service that has constructor parameters that can only be resolved at runtime, is there a way to leverage container-driven decoration?
Consider the following class which relies on a parameter that is only defined at runtime:
interface IFooService
{
void DoServicyStuff();
}
class MyFooService : IFooService
{
public MyFooService(string somePeskyRuntimeArgument)
{
this.peskyValue = somePeskyRuntimeArgument;
}
public void DoServicyStuff()
{
// do some stuff here with the peskyValue...
}
}
Since the value can only be provided at runtime, we need to move away from the constructor injection and into a method-level parameter passing. This is commonly achieved using a factory implementation like this:
interface IFooServiceFactory
{
IFooService CreateService(string heyItsNowAMethodLevelPeskyParameter);
}
class FooServiceFactory : IFooServiceFactory
{
public IFooService CreateService(string heyItsNowAMethodLevelPeskyParameter)
{
return new MyFooService(heyItsNowAMethodLevelPeskyParameter);
}
}
While this works fine if the intent is to just abstract away the construction of the service, it poses a challenge to decorate the IFooService instance.
For scenarios where no runtime parameter is involved, this can be easily achieved by tapping into the container to provide our service for us. The example below uses the Scrutor library to decorate the interface with a logging decorator implementation:
class FooServiceFactory : IFooServiceFactory
{
private readonly IServiceProvider serviceProvider;
public FooServiceFactory(IServiceProvider serviceProvider)
{
this.serviceProvider = serviceProvider
}
public IFooService CreateService(string heyItsNowAMethodLevelPeskyParameter)
{
return this.serviceProvider.GetRequiredInstance<IFooService>();
}
}
...
services
.AddTransient<IFooService, MyFooService>()
.AddTransient<IFooServiceFactory, FooServiceFactory>()
.Decorate<IFooService, LoggingFooService>();
But since MyFooService takes a primitive value as an argument, we cannot rely on GetRequiredService<T> to obtain the instance, as it will fail to find "a registration for string" when building the concrete class.
Similarly, changing the factory to rely on ActivatorUtilities's .CreateInstance or .CreateFactory methods will end up creating the objects while completely ignoring the container registrations, thus leaving us without any decorator.
I know I have at least 2 options to decorate the objects manually, namely:
Using the factory itself to manually create the decorator:
public IFooService CreateService(string heyItsNowAMethodLevelPeskyParameter)
{
return new LoggingService(
new MyFooService(heyItsNowAMethodLevelPeskyParameter));
}
Using a factory decorator to inject a decorator after the instance is created:
abstract class FooServiceFactoryDecorator : IFooServiceFactory
{
private readonly IFooServiceFactory fooServiceFactory;
protected FooServiceFactory(IFooServiceFactory fooServiceFactory)
{
this.fooServiceFactory = fooServiceFactory;
}
public virtual IFooService CreateService(string heyItsNowAMethodLevelPeskyParameter)
{
return this.fooServiceFactory.CreateService(heyItsNowAMethodLevelPeskyParameter);
}
}
class LoggingFooServiceFactory : FooServiceFactoryDecorator
{
private readonly IFooServiceFactory fooServiceFactory;
public FooServiceFactory(IFooServiceFactory fooServiceFactory)
{
this.fooServiceFactory = fooServiceFactory;
}
public override IFooService CreateService(string heyItsNowAMethodLevelPeskyParameter)
{
return new LoggingFooService(
this.fooServiceFactory.CreateService(heyItsNowAMethodLevelPeskyParameter));
}
}
...
services
.AddTransient<IFooServiceFactory, FooServiceFactory>()
.Decorate<IFooServiceFactory, LoggingFooServiceFactory>()
Neither of these allows me to directly use .Decorate on top of the service interface. The first option works but is heavily coupled (meaning I'd have to keep changing it if I want to add other decorators into the mix), while the second version is less coupled, but still forces me to writing one factory decorator per service decorator and thus leads into a much more complex solution.
Another pain point is dependencies on the decorators themselves (for example, ILogger<T> on the LoggingFooService), which I could potentially solve by leveraging ActivatorUtilities to create the decorators instead of newing them up manually.
I could also potentially generalize the "factory decorator" so that the decoration function is parameterized and thus the class can be reused, but it is still very convoluted and hard to maintain, while also not providing as good a syntax for consumers to add new decorators.
class DecoratedFooServiceFactory<TDecorator> : FooServiceFactoryDecorator
where TDecorator : IFooService
{
private readonly IFooServiceFactory fooServiceFactory;
private readonly IServiceProvider serviceProvider;
public FooServiceFactory(
IFooServiceFactory fooServiceFactory,
IServiceProvider serviceProvider)
{
this.fooServiceFactory = fooServiceFactory;
this.serviceProvider = serviceProvider;
}
public override IFooService CreateService(string heyItsNowAMethodLevelPeskyParameter)
{
return ActivatorUtilities.CreateInstance<TDecorator>(
this.serviceProvider,
this.fooServiceFactory.CreateService(heyItsNowAMethodLevelPeskyParameter));
}
}
...
services
.AddTransient<IFooServiceFactory, FooServiceFactory>()
.Decorate<IFooServiceFactory, DecoratedFooServiceFactory<LoggingFooService>>()
And finally, if I ever want to move away from using a factory and want to change to using the service directly, this will cause a significant setup change where I'd then have to configure all the decorators again in the container directly instead of just removing the factory registration as one normally would do.
How can I use a factory like this, while still keeping the capability of configuring decorators at the container level using the simple Scrutor syntax?
Ok, a couple of disclaimers first:
I agree with Steven here in that this looks like an anti-pattern and you will probably be better off redesigning your code to not require run-time values on service construction.
I additionally want to caution against using scrutor-like Decorate. While much less confident in this than in the first point, I believe hiding logging in decorators is much less convenient in the long run than it seems at first. Or at least that's what I saw after about a year of trying them out.
That said, let's see what can be done.
First, let's put some constraints on where the value is coming from. Specifically, let's say we can have a service providing that value, that looks like this:
public interface IValueProvider
{
string Get();
}
This actually allows us to have quite a bit of range. Implementation of that interface can:
Get value from external API - once or periodically in the background. It can even call it every time Get is called, but this is a very bad idea, as it will make construction asynchronous.
Get value that is stored in memory and allow some other service to update it. Say, expose a 'configuration' endpoint where a user can set a new value every once in a while.
Calculate the value based on some algorithm of your choice.
Once you have this service, you can register it like this:
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<IValueProvider, AwesomeValueProvider>();
services.AddSingleton<IFooServiceFactory, FooServiceFactory>();
services.AddTransient<IFooService>(sp =>
{
var factory = sp.GetRequiredService<IFooServiceFactory>();
var valueProvider = sp.GetRequiredService<IValueProvider>();
return factory.Create(valueProvider.Get());
});
}
Hope this helps
I came across an interesting article: AOP Aspects as mocks in JUnit
Since I have requirement to mock multiple final and private static variables, I am planning to use AOP in place of reflection or PowerMockito as they are causing issues with SpringJUnit4ClassRunner.
Is there any way I can use #Aspect for test classes without using the annotation #EnableAspectJAutoProxy? (I want to use an aspect targeting class X only in one test case.)
This is a sample of what I want to do.
The question is answered(adding for discussion on what could be done)
//External class
public final class ABC(){
public void method1() throws Exception {}
}
#Service
public void DestClass() {
private static final ABC abc = new ABC();
public Object m() {
// code (...)
try {
abc.method1();
}
catch(Exception e) {
// do something (...)
return null;
}
// more code (...)
}
}
Spring framework allows to programmatically create proxies that advise target objects , without configuring through #EnableAspectJAutoProxy or <aop:aspectj-autoproxy>
Details can be found in the documentation section : Programmatic Creation of #AspectJ Proxies and the implementation is pretty simple.
Example code from the documentation.
// create a factory that can generate a proxy for the given target object
AspectJProxyFactory factory = new AspectJProxyFactory(targetObject);
// add an aspect, the class must be an #AspectJ aspect
// you can call this as many times as you need with different aspects
factory.addAspect(SecurityManager.class);
// you can also add existing aspect instances, the type of the object supplied must be an #AspectJ aspect
factory.addAspect(usageTracker);
// now get the proxy object...
MyInterfaceType proxy = factory.getProxy();
Please note that with Spring AOP , only method executions can be adviced. Excerpt from the documentation
Spring AOP currently supports only method execution join points
(advising the execution of methods on Spring beans). Field
interception is not implemented, although support for field
interception could be added without breaking the core Spring AOP APIs.
If you need to advise field access and update join points, consider a
language such as AspectJ.
The document shared with the question is about aspectj and without providing the sample code to be adviced it is hard to conclude if the requriement can acheived through Spring AOP. The document mentions this as well.
One example of the integration of AspectJ is the Spring framework,
which now can use the AspectJ pointcut language in its own AOP
implementation. Spring’s implementation is not specifically targeted
as a test solution.
Hope this helps.
--- Update : A test case without using AOP ---
Consider the external Class
public class ABCImpl implements ABC{
#Override
public void method1(String example) {
System.out.println("ABC method 1 called :"+example);
}
}
And the DestClass
#Service
public class DestClass {
private static final ABC service = new ABCImpl();
protected ABC abc() throws Exception{
System.out.println("DestClass.abc() called");
return service;
}
public Object m() {
Object obj = new Object();
try {
abc().method1("test");
} catch (Exception e) {
System.out.println("Exception : "+ e.getMessage());
return null;
}
return obj;
}
}
Following test class autowires the DestClass bean with overridden logic to throw exception . This code can be modified to adapt to your requirement.
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes = { DestClassSpringTest.TestConfiguration.class })
public class DestClassSpringTest {
#Configuration
static class TestConfiguration {
#Bean
public DestClass destClass() {
return new DestClass() {
protected ABC abc() throws Exception {
// super.abc(); // not required . added to demo the parent method call
throw new Exception("Custom exception thrown");
}
};
}
}
#Autowired
DestClass cut;
#Test
public void test() {
Object obj = cut.m();
assertNull(obj);
}
}
Following will be the output log
DestClass.abc() called // this will not happen if the parent method call is commented in DestClassSpringTest.TestConfiguration
Exception : Custom exception thrown
The article you are referring to is using full AspectJ, not Spring AOP. Thus, you do not need any #EnableAspectJAutoProxy for that, just
either the AspectJ load-time weaver on the command line when running your test via -javaagent:/path/to/aspectjweaver.jar
or the AspectJ compiler activated when compiling your tests (easily done via AspectJ Maven plugin if you use Maven)
Both approaches are completely independent of Spring, will work in any project and even when using Spring also work when targeting execution of third party code because no dynamic proxies are needed unlike in Spring AOP. So there is no need to make the target code into a Spring bean or to create a wrapper method in your application class for it. When using compile-time weaving you can even avoid weaving into the third party library by using call() instead of execution() pointcut. Spring AOP only knows execution(), AspectJ is more powerful.
By the way: Unfortunately both your question and your comment about the solution you found are somewhat fuzzy and I do not fully understand your requirement. E.g. you talked about mocking final and private static variables, which would also be possible in other ways with AspectJ by using set() and/or get() pointcuts. But actually it seems you do not need to mock the field contents, just stub the results of method calls upon the objects assigned to those fields.
When using spring-data-rest there is a post processing of Resource classes returned from Controllers (e.g. RepositoryRestControllers). The proper ResourceProcessor is called in the post processing.
The class responsible for this is ResourceProcessorHandlerMethodReturnValueHandler which is part of spring-hateoas.
I now have a project that only uses spring-hateoas and I wonder how to configure ResourceProcessorHandlerMethodReturnValueHandler in such a scenario. It looks like the auto configuration part of it still resides in spring-data-rest.
Any hints on how to enable ResourceProcessorHandlerMethodReturnValueHandler in a spring-hateoas context?
I've been looking at this recently too, and documentation on how to achieve this is non-existent. If you create a bean of type ResourceProcessorInvokingHandlerAdapter, you seem to lose the the auto-configured RequestMappingHandlerAdapter and all its features. As such, I wanted to avoid using this bean or losing the WebMvcAutoConfiguration, since all I really wanted was the ResourceProcessorHandlerMethodReturnValueHandler.
You can't just add a ResourceProcessorHandlerMethodReturnValueHandler via WebMvcConfigurer.addReturnValueHandlers, because what we need to do is actually override the entire list, as is what happens in ResourceProcessorInvokingHandlerAdapter.afterPropertiesSet:
#Override
public void afterPropertiesSet() {
super.afterPropertiesSet();
// Retrieve actual handlers to use as delegate
HandlerMethodReturnValueHandlerComposite oldHandlers = getReturnValueHandlersComposite();
// Set up ResourceProcessingHandlerMethodResolver to delegate to originally configured ones
List<HandlerMethodReturnValueHandler> newHandlers = new ArrayList<HandlerMethodReturnValueHandler>();
newHandlers.add(new ResourceProcessorHandlerMethodReturnValueHandler(oldHandlers, invoker));
// Configure the new handler to be used
this.setReturnValueHandlers(newHandlers);
}
So, without a better solution available, I added a BeanPostProcessor to handle setting the List of handlers on an existing RequestMappingHandlerAdapter:
#Component
#RequiredArgsConstructor
#ConditionalOnBean(ResourceProcessor.class)
public class ResourceProcessorHandlerMethodReturnValueHandlerConfigurer implements BeanPostProcessor {
private final Collection<ResourceProcessor<?>> resourceProcessors;
#Override
public Object postProcessAfterInitialization(Object bean, String beanName)
throws BeansException {
if (bean instanceof RequestMappingHandlerAdapter) {
RequestMappingHandlerAdapter requestMappingHandlerAdapter = (RequestMappingHandlerAdapter) bean;
List<HandlerMethodReturnValueHandler> handlers =
requestMappingHandlerAdapter.getReturnValueHandlers();
HandlerMethodReturnValueHandlerComposite delegate =
handlers instanceof HandlerMethodReturnValueHandlerComposite ?
(HandlerMethodReturnValueHandlerComposite) handlers :
new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
requestMappingHandlerAdapter.setReturnValueHandlers(Arrays.asList(
new ResourceProcessorHandlerMethodReturnValueHandler(delegate,
new ResourceProcessorInvoker(resourceProcessors))));
return requestMappingHandlerAdapter;
}
else return bean;
}
}
This has seemed to work so far...
First of all I want to say I'm pretty new in programming with ejb and jsf, and I'm trying to complete a project started by a friend of mine.
I'm getting a NullPointerException caused by the invoke of the method utenteSessionBean.CheckUtentebyId(username) of the session bean object called utenteSessionBean, declared inside the managed bean called Neo4jMBean.
I learned that it's not necessary creating and initializing a session bean (as you must do with a normal java object) in managed bean, but it's enough declaring it.
Here is the code of the session bean, which retrieves data from a DB
#Stateless
#LocalBean
public class UtenteSessionBean {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("EnterpriseApplication2-ejbPU");
public boolean CheckUtentebyId(String username){
EntityManager em = emf.createEntityManager();
Query query = em.createNamedQuery("Utente.findByUsername");
query.setParameter("username", username);
List<Utente> Res=query.getResultList();
//completare funzione ctrl+spazio
System.out.println("pre");
System.out.println("pre"+Res.isEmpty());
em.close();
System.out.println("post");
System.out.println("post"+Res.isEmpty());
if(Res.size()>=1)
{
return true;
}
else
{
return false;
}
}
}
Here's the code of the managed bean:
#ManagedBean
#ViewScoped
public class Neo4jMBean {
#EJB
private UtenteSessionBean utenteSessionBean;
static String SERVER_ROOT_URI = "http://localhost:7474/db/data/";
public Neo4jMBean() {
}
public boolean getUser(String username) {
return utenteSessionBean.CheckUtentebyId(username);
}
}
I've searched on StackOverFlow many times a solution for fixing this problem, but I haven't found something that works for me yet.
I fixed it accessing the EJB Components using JNDI.
In few words, if i use an EJB in a managed bean method, i need to add the next lines of code:
InitialContext ic = new InitialContext();
SessionBeanName = (SessionBeanClass) ic.lookup("java:global/NameOfTheApplication/NameOfTheEJBpackage/NameOfTheSessionBean");
It must be surronded by a try-catch statement
Create empty beans.xml file in your WEB-INF folder to enable CDI
My app has a ProviderFactory static class that has static utility methods passing back static instances of things like a logger. The rest of my app then can just grab a/the reference to the logger from anywhere without having to pass in the logger (common design practice).
So, another part of my app, the DbCacheProvider, has methods that make calls to the logger so internally it gets a reference to the logger from the factory and then issues calls to it.
My question is that using Moq, I want to verify methods on the logger are being called by the methods within the DbCacheProvider. I can do this using dependency injection when I pass a mock logger into the DbCacheProvider as a parameter, but I'm not passing the logger in (not do I want to). So, how would I verify the DbCacheProvider is making calls to the logger?
If you don't want to pass the logger in through the constructor you'd need to change your ProviderFactory while running unit tests to return your mocked logger.
Anyway there are a couple of reasons it's often suggested to set up dependency injection:
Your tests are more straightforward and don't involve finagling with custom factories
IoC frameworks like Unity, Ninject and Autofac make it easy to create objects when their dependencies are set up this way. If you set up all of your objects this way, the framework will do all the heavy lifting of creating the right objects and passing them in for you. The dependency injection is done automatically and won't be a burden for you.
Old question without an answer, I had a similar problem and solved it like this:
I have the following sample code and need to verify that not only was a method called but was called with a specific value.
public interface ILog
{
void Info(string message);
}
public interface ILogFactory
{
ILog GetLogger();
}
This is the class being tested, where the interface items are being injected:
public class NewAction
{
readonly ILogFactory _logger;
public NewAction(ILogFactory logger)
{
_logger = logger;
}
public void Step1()
{
_logger.GetLogger().Info("Step 1");
}
public void Step2()
{
_logger.GetLogger().Info("Step 2");
}
}
This is obviously a very simplistic view of my actual code, but I needed to verify that Step1 and Step2 are behaving as expected and passed the correct values to the Log, this would mean I also needed to ensure they occurred in the right order. My test:
[TestClass]
public class UnitTest1
{
[TestMethod]
public void TestMethod1()
{
// Arrange
var log = new Mock<ILog>();
var factory = new Mock<ILogFactory>();
factory.Setup(l => l.GetLogger()).Returns(log.Object);
// Act
var action = new NewAction(factory.Object);
action.Step1();
action.Step2();
// Assert
factory.Verify(l => l.GetLogger());
log.Verify(l => l.Info(It.Is<string>(s => s == "Step 1")));
log.Verify(l => l.Info(It.Is<string>(s => s == "Step 2")));
}
}
Hope this helps.