Below is my Spring Boot starter class.
#SpringBootApplication
#ComponentScan({"com.example"})
#EntityScan("com.example.entity")
#EnableJpaRepositories("com.example.repository")
public class SpringAppApplication {
public static void main(String[] args) {
SpringApplication.run(SpringAppApplication.class, args);
}
}
Now, how can I configure something like #ComponentScan({"com.example.*"})
so that I can avoid adding #EntityScan("com.example.entity") and #EnableJpaRepositories("com.example.repository")
#SpringBootApplication annotation is actualy 3 annotations in one which includes the #ComponentScan (take a look here). And if you have it in the root package of your project (which is considered a good practice) you do not have to do anything there.
#EntityScan and #EnableJpaRepositories are different and are related to spring data library so it really kinda makes sense NOT to have them included in #SpringBootApplication.
Because these annotations could easily be on a configuration class for database or something like that (separating your configuration classes also has it's benefits sometimes).
If you want, you can always write your own custom annotation and inherit the two (or 4) annotations you want. There are plenty of online resources out there on the topic.
Related
I was going through this tutorial where the instructor was configuring Spring Data JPA. He had created the Entity classes and Repository interfaces and then added the #EnableJpaRepositories and #EntityScan annotations on the main application as follows:
#SpringBootApplication
#ComponentScan({"com.test.controller", "com.test.services"})
#EnableJpaRepositories("com.test.repository")
#EntityScan("com.test.entity")
public class MainApplication{
public static void main(String args[]){
SpringApplication.run(MainApplication.class, args[]);
}
}
I was creating the same project on the side, which had the same Entity classes and Repository interfaces but my main application didn't have these annotations. Instead, I added only #SpringBootApplication. Despite the absence of the said annotations, I found the code to be working well and fetching data from the db without issues. So my question is, what is the advantage of adding these annotations to the code ? Is it just for specifying the package where you can find the corresponding files, or are there any other advantages ?
By default, Spring searches for entities and repos in package where you placed your main class (and below this package). For example having these packages:
java
-com
---pack1
-----AnyEntity.java
---pack2
-----Main.java
Spring won't be able to find AnyEntity automatically. In this situation you need to specify where the entity is using #EntityScan. When it comes to repositories, you deal with it similarly using #EnableJpaRepositories.
In our app I found out, that my integration tests picks up more stuff than I'd like. I'd like to know, how correctly structured app configuration looks like, what do you use, so that I can #Import in tests only those configuration which are used in production, which are needed.
I believe relevant page in documentation is:
https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#boot-features-testing-spring-boot-applications-testing-user-configuration
... it's stressed there, that it's important to structure code in sensible way, however it's not shown that much, what that is/means. I know about profiles and can probably create profile which would be unmatched in tests and import manually, but that's probably not that sensible way they were talking about.
Consider this main entrypoint:
#SpringBootApplication
public class DemoApplication {
private final SomeService someService;
public DemoApplication(SomeService someService) {
this.someService = someService;
}
#EventListener(ApplicationReadyEvent.class)
public void started() {
System.out.println(someService.doIt());
}
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
interface of some service:
public interface SomeService {
public String doIt();
}
and configuration:
#Configuration
public class Config {
#Bean
public SomeService createSomeServiceBean() {
return new SomeService() {
#Override
public String doIt() {
return String.format("Hi! (At %s)", LocalDateTime.now());
}
};
}
}
When invoked, entrypoint annotated by #SpringBootApplication will do component scan, will discover configuration and it will work. Reading further in documentation we will find sentence: Test slices exclude #Configuration classes from scanning([if #ComponentScan does have default value of basePackages and basePackagesClasses]), however following test:
#SpringBootTest
class DemoApplicationTests {
#Autowired
private SomeService someService;
#Test
void contextLoads() {
System.out.println(someService.doIt());
}
}
just happily discovers SomeService bean defined. Or did that sentence meant just that tests annotated by for example #DataJpaTest won't register some configurations? Kinda unclear to me, but it does not seem possible, since how would #DataJpaTest would know, which configurations to ommit and which not.
Again, I know how to use profiles/excluding configurations. I'm asking about "sensible way of structuring app".
How to sensibly structure you app and how to configure it so that:
#SpringBootApplication annotated entrypoint will do component scan, find and use configurations, for production, but these configurations needs to be manually imported in tests?
some packages will be automatically scanned for configurations which will be used both in development and tests environments.
The Spring Boot Test support provides annotations that allow to only create a Spring Context with the relevant beans to testing a specific slice of your application.
There is no specific package structure or naming strategy required to make use of this feature.
Here are some of these:
#DataJpaTest: You get a Spring Context with relevant beans to test your JPA <-> Database interface: EntityManager, DataSource, all your interfaces extending JpaRepository
#WebMvcTest: You get a Spring Context with a mocked servlet environment for testing your web layer that includes the following beans for your: all your controller, controller advice, WebMvcConfigurer , Filter, etc. but not anything that is annotated with e.g. #Service or #Component
#SpringBootTest: This will give you a full Spring Context and tries to create all beans for you. You can exclude some autoconfiguration e.g. if you don't want autoconfiguration to kick in:
Example:
#SpringBootTest(webEnvironment = RANDOM_PORT)
#TestPropertySource(properties=
{"spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration"})
There are way more test slice annotations, you can have a look at here
So these annotations are smart in a way that they know which beans they should include in the context and which to exclude.
A general approach to testing your application can be to use the first two test annotations stated above to verify web and data layer in isolation. Next use Mockito and plain JUnit 5 to unit test your service classes. And finally, write some integration test that creates the whole Spring Context with #SpringBootTest to test everything together.
I am trying to write an autoconfigure / starter module for one of my project. This module handles the persistence through Spring Data JPA. It aims at providing several spring data repositories.
Right now, my autoconfiguration looks like this:
#Configuration(proxyBeanMethods = false)
#AutoConfigureAfter(JpaRepositoriesAutoConfiguration::class)
#EnableJpaRepositories(basePackageClasses = [ItemRepository::class])
#EntityScan(basePackageClasses = [ItemRepository::class])
class DomainPersistenceDataJpaAutoConfiguration() {
}
As stated in spring boot reference documentation, auto configuration should not enable component scanning, although #EnableJpaRepositories uses component scanning.
What would be a good alternative approach? Is there any example of existing spring boot start which provides repositories implementation I could consult?
What you're looking for is probably
AutoConfigurationPackages#register method, I think the common approach would be to implement ImportBeanDefinitionRegistrar and import this implementation in your autoconfiguration using #Import. A very elegant solution can be seen in Axon framework's RegisterDefaultEntities annotation and DefaultEntityRegistrar which it imports. This way your packages will be included in jpa and entity scans.
Edit: Adding actual example since as the review pointed out, the links might change over time.
In your case the ImportBeanDefinitionRegistrar could look something like this:
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.boot.autoconfigure.AutoConfigurationPackages;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.type.AnnotationMetadata;
public class StarterEntityRegistrar implements ImportBeanDefinitionRegistrar {
#Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
AutoConfigurationPackages.register(registry, ItemRepository.class.getPackageName());
}
}
and your autoconfiguration would be just:
#Configuration(proxyBeanMethods = false)
#AutoConfigureAfter(JpaRepositoriesAutoConfiguration.class)
#Import(StarterEntityRegistrar.class)
class DomainPersistenceDataJpaAutoConfiguration() {
}
I am using spring-boot 2.0.4; I have a bunch of services and they have a common configuration class marked with #Configuration.
I want to move this to a common dependency which will have this #Configuration, and based on the need, any micro-service can use #ComponentScan to activate this configuration from dependency.
I have done this for #Component classes, and it's working fine. I activate any particular component I need by adding it into #ComponentScan. How can I activate the configuration in a similar manner(based on need).
Here are the code examples:
Common Configuration:
package abc.department.common.configs.mongo
#Component
public class AbcMongo {
#Bean
public MongoTemplate mongoTemplate() {
// ... create MongoTemplate.
return createdMongoTemplate;
}
}
Here is a class which uses the above dependency:
#Configuration
#ComponentScan("abc.department.common.configs.mongo")
public class MyServiceConfigs {
}
Similarly, I want to do something like this:
package abc.department.common.configs.security.web
#Configuration
#EnableWebSecurity
public class AbcWebSecurity extends WebSecurityConfigurerAdapter {
#Override
protected void configure(HttpSecurity http) throws Exception {
// ... do common configs;
}
}
and now, if a service would need web-security config, it could get like:
#Configuration
#ComponentScan({"abc.department.common.configs.mongo","abc.department.common.configs.security.web"})
public class MyServiceConfigs {
}
#Configuration is meant to specify the beans, for example:
#Configuration
public class MyMongoConfiguration {
#Bean
public MongoTemplate mongoTemplate() {
return new ...
}
#Bean
public MySampleBean mySampleBean(MongoTemplate tpl) {
return new MySampleBean(tpl);
}
}
But if so why do you need to work with #Component at all (at least for the beans you create)?
Configuration is a special bean used by Spring framework to load other beans and it can be viewed as a "substitution"/alternative technique to component scanning.
I believe that, if you have some infrastructure configuration that loads a bunch of "infrastructure beans" (shared jar if I get you right), then the services that use this jar should only say "Hey, I want to load this configuration" and not to scan inside the packaging structure of that jar. Why do I think so?
What if you decide to add new beans into a new package in the infra, should external services change their code and define an additional folder to scan? - Probably no.
What if you decide to move the infra to another package?
Now in Spring there are two simple ways to do this that come to mind:
Way 1: Use #Import Annotation
#Configuration // this is from "shared artifact"
class MyInfraConfiguration {
}
#Configuration // this is from an "applicative service" that uses the infra jar in dependencies
#Import(MyInfraConfiguration.class)
class ServiceAConfiguration {
}
Way 2: Use Spring Factories mechanism
The first way has a drawback: You need to know in a Service what infra configuration exactly is. If you see it as a drawback, consider using spring factories.
Spring factories allow registering the infra configuration in some file so that spring boot will load it in service one automatically, you won't even need to mention MyInfraConfiguration in the Service Configuration, just add a dependency to the infra jar and it will work.
In the infra component create:
META-INF/spring.factories
And add there:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.mycompany.myinfra.whatever.InfraConfiguration
That's it.
Now if you want to customize the loading of beans in the infra configuration, like, a creation of Mongo related templates only if some properties are available, you might want to use #Conditional. Now, although this is kind of out of scope for this question, I mention this because in conjunction with spring factories this can create a very flexible way to manage your configurations
I am writing a library to provide some functionality that is shared between multiple different Spring Boot applications that I work with.
I would like to do something similar to the auto-configuration that is provided by the many Spring Boot starter libraries exist. That, or some other simple declarative way to integrate my library with the ApplicationContext of the apps using it.
I have found some resources explaining how auto configuration works. I can figure out the above problem.
However, I have not been able to find any good examples of how I can test as part of my library's test suite that it suitably integrates with a Spring Boot application. Ideally, I would start up a simple Spring Boot app written in the library's test directly just for the sake of testing, add the right annotation to it, and be able to assert that the correct beans are then configured.
I have tried creating a TestApplication class that does that and writing integration tests using the SpringBootTest annotation but the TestApplication was never started before my test started.
What can I do to start up a simple app like that solely for the purpose of testing my library? My tests are written with Spock and Spock-Spring in case that changes things versus other test frameworks.
I was able to make it work with the following test class:
#SpringBootTest
#ContextConfiguration(classes = TestApplication)
class DummyIntegrationSpec extends Specification {
#Autowired
DummyService dummyService
void 'dummy service should exist'() {
expect:
dummyService.getMessage() == DummyConfiguration.MESSAGE
}
}
and this TestApplication class at src/test/groovy/com/example/project/TestApplication.groovy
#SpringBootApplication(scanBasePackages = 'com.example.project.config')
#EnableAutoConfiguration
class TestApplication extends SpringBootServletInitializer {
#Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(TestApplication)
}
static void main(String[] args) {
SpringApplication.run(TestApplication, args)
}
}
The two key changes I had to make in order for the TestApplication to start and load the correct context when I moved my TestApplication class from src/main to src/test were:
the TestApplication class needed to be added to the ContextConfiguration annotation
the package that my library's Java config files live in needed to be added to the SpringBootApplication scanBasePackages field
The library auto-configuration does follow a similar structure to the one mentioned in the link tom provided.
Your auto-configuration should be automatically picked while your main spring application/test is starting and all beans will be registered in your context. They will be available for auto-wiring and follow your conditions and init order.
As a summary, make sure you have an auto-configuration annotated by #Configuration class with an #Import that imports your #Configuration annotated configuration classes (inside of them you define beans with methods annotated with #Bean). Also make sure you created a spring.factories file that include your auto-configuration class and that you removed the spring boot maven plugin (for the packaging to be right).
Also, make sure your auto-configuration project is NOT annotated by things like #SpringBootApplication, #EnableAutoConfiguration, #ComponentScan or other spring boot annotations that need to be only in the main spring boot projects (There should be one of them in each stack).
Please also see the article below:
Spring boot is based on a lot of pre-made auto-configuration parent projects. You should already be familiar with spring boot starter projects.
You can easily create your own starter project by doing the following easy steps:
Create some #Configuration classes to define default beans. You should use external properties as much as possible to allow customization and try to use auto-configuration helper annotations like #AutoConfigureBefore, #AutoConfigureAfter, #ConditionalOnBean, #ConditionalOnMissingBean etc. You can find more detailed information on each annotation in the official documentation Condition annotations
Place an auto-configuration file/files that aggregates all of the #Configuration classes.
Create a file named spring.factories and place it in src/main/resources/META-INF.
In spring.factories, set org.springframework.boot.autoconfigure.EnableAutoConfiguration property with comma separated values of your #Configuration classes:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=
com.mycorp.libx.autoconfigure.LibXAutoConfiguration,
com.mycorp.libx.autoconfigure.LibXWebAutoConfiguration
Using this method you can create your own auto-configuration classes that will be picked by spring-boot. Spring-boot automatically scan all maven/gradle dependencies for a spring.factories file, if it finds one, it adds all #Configuration classes specified in it to its auto-configuration process.
Make sure your auto-configuration starter project does not contain spring boot maven plugin because it will package the project as an executable JAR and won't be loaded by the classpath as intended - spring boot will not be able to find your spring.factories and won't load your configuration