Suppose I have a jar with a Spring Component called MyComponent. This jar is a Spring Boot "autoconfigured" jar, meaning that it has a Configuration class (annotated with #Configuration), and additionally, a META-INF/spring.factories file on the classpath. This jar is not an executable jar by itself; it is a library that is meant for inclusion in a Spring Boot application.
These files look as follows:
MyComponent.java, in package com.mine.components:
#Component
public class MyComponent {
private static final Logger logger = LoggerFactory.getLogger(MyComponent.class);
#PostConstruct
public void init() {
logger.info("MyComponent inited");
}
}
MyConfiguration.java, in package com.mine.config:
#Configuration
#ComponentScan(basePackages = "com.mine.components")
public class MyConfiguration {
}
spring.factories, in META-INF under src/main/resources:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.mine.config.MyConfiguration
If I include this jar in a Spring Boot project with the above three files, the MyComponent component is NOT detected (the log message never prints).
But if I instead remove the #ComponentScan and declare MyComponent using the #Bean annotation as follows, it is detected:
#Bean
public MyComponent myComponent() {
return new MyComponent();
}
Why?
Difference beetween ComponentScan and declared Bean inside #Configuration class:
#ComponentScan: You enable auto-scanning (default using current folder path), optionally you can specify an basePackage where spring will found yours beans.
#ComponentScan(basePackages = "com.mine.components")
You're saying to Spring that in this package("com.mine.components"), you'll define yours beans typically using annotations (#Component, #Entity, #Controller, #Service, #Repository or more).
#Bean: This way you define your beans manually inside #Configuration class, but Spring has to discover your configuration class, usually using #ComponentScan, #SpringBootApplication.
META-INF/spring.factories: you define an custom autoconfiguration
Related
I'm a little new t working with Spring so any help provided would be great.
I have a SpringApplication class (annotated with #SpringBootApplication. In another class (within the same project), it contains a ServiceClass class. When the class is in the same project, it runs as expected.
When the ServiceClass is moved to an external jar, I get the following error.
Description:
Field service in
package-to-class.Comp required a
bean of type 'package-to-class.ServiceClass'
that could not be found.
The injection point has the following annotations:
#org.springframework.beans.factory.annotation.Autowired(required=true)
Action:
Consider defining a bean of type
'package-to-class.ServiceClass' in your
configuration.
I am trying to find what I need to do to inject (#AutoWired) into my project with the above error.
By default, Spring Boot's component scanning only looks in the same package as the #SpringBootApplication and its descendants.
The approach I would suggest is using #Import to import specific beans from outside the project, or use #ComponentScan to import all beans from a package in another project.
#SpringBootApplication
#Import(ServiceClass.class)
public class SpringApplication {
// ...
}
or
#SpringBootApplication
#ComponentScan(basePackages = "com.example.mylibrary")
public class SpringApplication {
// ...
}
Okey some basic things, you have mixed up your packages a bit.
#SpringBootApplication will scan all classes in packages below the class this is annotated on. This annotation is an alias for #EnableAutoConfiguration, #Configuration and #ComponentScan means that #ComponentScan(basePackages = {"com.springdi.example"}, basePackageClasses = DependencyBasePackageClass.class) is not needed.
com.springdi.example // class with #SpringBootApplication annotation
|
|
|
com.springdi.example.* // Will find all #Service, #Component, #Configuration
// in subpackages below the #SpringBootApplication
// annotation
You can read more about the annotation here SpringBootApplication
Since your other annotated classes are NOT in the same package structure as the #SpringBootApplication you need to define all the places you want to scan for annotations.
#SpringBootApplication(scanBasePackages = {"com.springdi.example", "com.dependency.example"})
will probably include all the packages that you want to scan through.
I have two Maven modules.
The first one, called "application", contains the spring boot Application class that just contains these lines:
package org.example.application;
#SpringBootApplication
#ComponentScan({"org.example.model", "org.example"})
public class Application {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(Application.class, args);
}
}
In the same Maven module and package, org.example.application, I have a RestController that uses a Component that in turn uses the components of the other Maven module described below.
The other Maven module, called "model", contains the spring boot components (crud-repositories, entities etc). All those classes are under the same package structure as the first Maven module (org.example) but in subpackages of that, like org.example.model.entities, org.example.model.repositories etc.
So, the flow is like this:
Maven module application in package org.example:
SpringBootApplication -> RestController -> MyComponent
And the components that should be autowired in MyComponent are the ones in the model Maven module under the package org.example.model.
But when I start the application I just get the error:
***************************
APPLICATION FAILED TO START
***************************
Description:
Field myRepository in org.example.MyComponent required a bean of type 'org.example.model.repositories.MyRepository' that could not be found.
Action:
Consider defining a bean of type 'org.example.model.repositories.MyRepository' in your configuration.
org.example.model.repositories.MyRepository does exist in Maven module "model" but cannot be found by the SpringBootApplication class!
As you can see, I have tried to explicitly define the scan components to:
#ComponentScan({"org.example.model", "org.example"}) but that does not seem to help.
So what have I done wrong?
The first thing that you should wonder is : why do you declare #ComponentScan while one of the goal of #SpringBootApplication is (among other things) to enable the component scan ?
From Spring Boot documentation :
The #SpringBootApplication annotation is equivalent to using
#Configuration, #EnableAutoConfiguration and #ComponentScan with their
default attributes
Note that when on the class of your Spring Boot Application, you declare #ComponentScan to specify a value as basePackages, it overrides the basePackages used by default by #SpringBootApplication that is the current package where the class resides. So to have as base package both the package of the Spring Boot Application class and the additional packages that were missing, you have to explicitly set them.
Besides basePackages is recursive. So to enable the scan both for classes locating in the "org.example" and "org.example.model" packages, specifying "org.example" is enough as "org.example.model" is a sub-package of it.
Try that :
#SpringBootApplication(scanBasePackages={"org.example"})
Or alternatively :
#SpringBootApplication
#ComponentScan("org.example")
When specify #EnableJpaRepositories/#ComponentScan/scanBasePackages in a Spring Boot Application ?
As you design your Spring Boot application layout, your have two cases :
1) case (to favor) where you use a package layout that provides the auto configuration of Spring Boot with zero configuration.
To summarize : if your classes annotated with Spring Bean stereotypes : #Component, #Repositories, #Repositories,... are located in the same package or a sub-package of the Spring Boot Application class, declaring only
#SpringBootApplication is all you need.
2) case (to avoid) where you don't use a package layout that provides the auto configuration of Spring Boot with zero configuration.
It generally means that you have candidate classes to scan that are not in the package (or sub-package) of your class annotated with #SpringBootApplication.
In this case, you add the scanBasePackages attribute or add #ComponentScan to specify packages to scan.
But additionally, if your repositories are not located in a package or sub-package of your class annotated with #SpringBootApplication, something else has to be declared such as : #EnableJpaRepositories(="packageWhereMyRepoAreLocated")
Here is the documentation about this part (emphasis is mine) :
80.3 Use Spring Data Repositories
Spring Data can create implementations of #Repository interfaces of
various flavors. Spring Boot handles all of that for you, as long as
those #Repositories are included in the same package (or a
sub-package) of your #EnableAutoConfiguration class.
For many applications, all you need is to put the right Spring Data
dependencies on your classpath (there is a
spring-boot-starter-data-jpa for JPA and a
spring-boot-starter-data-mongodb for Mongodb) and create some
repository interfaces to handle your #Entity objects. Examples are in
the JPA sample and the Mongodb sample.
Spring Boot tries to guess the location of your #Repository
definitions, based on the #EnableAutoConfiguration it finds. To get
more control, use the #EnableJpaRepositories annotation (from Spring
Data JPA).
Examples
1) case (to favor) where you use a package layout that provides the auto configuration of Spring Boot with zero configuration.
With a Spring Boot application declared in the org.example package, and all bean classes (Repositories included) declared in the same package or a sub-package of org.example, the following declaration is enough for the Spring Boot application :
package org.example;
#SpringBootApplication
public class Application {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(Application.class, args);
}
}
The repositories could be located in the org.example.repository package such as :
package org.example.repository;
#Repository
public interface FooRepository extends JpaRepository<Foo, Long>, { }
and
package org.example.repository;
#Repository
public interface BarRepository extends JpaRepository<Bar, Long>, { }
The controllers could be located in the org.example.controller package :
package org.example.controller;
#RestController
#RequestMapping("/api/foos")
public class FooController {...}
and so for...
2) case (to avoid) where you don't use a package layout that provides the auto configuration of Spring Boot with zero configuration.
With a Spring Boot application declared in the org.example.application package, and not all bean classes (Repositories included) declared in the same package or a sub-package of org.example.application, the following declaration will be required for the Spring Boot application :
package org.example.application;
#SpringBootApplication(scanBasePackages= {
"org.example",
"org.thirdparty.repository"})
#EnableJpaRepositories("org.thirdparty.repository")
public class Application {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(Application.class, args);
}
}
And the bean classes could be as below.
The repositories that may come from an external a JAR could be located in the org.thirdparty.repository package such as :
package org.thirdparty.repository;
#Repository
public interface FooRepository extends JpaRepository<Foo, Long>, { }
and
package org.thirdparty.repository;
#Repository
public interface BarRepository extends JpaRepository<Bar, Long>, { }
The controllers could be located in the org.example.controller package :
package org.example.controller
#RestController
#RequestMapping("/api/foos")
public class FooController {...}
and so for...
Conclusion : defining the Spring Boot application in the base package of your namespace is really encouraged to make the Spring Boot configuration as simple as possible.
I've got 2 different maven projects: project A and project B, where A is a maven dependency of B. Project A has a class annotated with #PropertySource:
#Component
#PropertySource({"classpath:spring-files/resource.properties"})
public class BeanAImpl implements BeanA{
#Value("#{\'${list.of.some.properties}\'.split(\',\')}")
private String someProperties;
}
In project B, I want to be able to define BeanAImpl. So I define it in my JavaConfig class of project B:
#Configuration
public class ProjectBConfig{
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
#Bean
public BeanA beanA() {
return new BeanAImpl();
}
I get a BeanCreationException, since the injection of the List into "someProperties" has failed. If I add to my #Configuration class (in project B) a component scan annotation for BeanAImpl's package, then the context will load successfully. Also, if I add the #PropertySource declaration to the config class - then it's going to work. But it seems that simply defining beanA in the configuration, does not take into account its annotations. I also tried changing beanA from #Component to #Configuration, which did not help.
Is there a way for me to have BeanAImpl inject the value from the properties by simply defining it as a bean, without needing to add extra configuration? Why is this happening?
#PropertySource annotation should be on class annotated with #Configuration, something similar to this:
#Configuration
#PropertySource({"classpath:spring-files/resource.properties"})
public class ProjectBConfig{
Or you can create separate configuration class in project A.
See javadoc for details of #PropertySource annotation.
I have a SpringBoot main application, as well as a separate Maven module project that compiles as a separate Jar. The module has a Spring config class annotated with #Configuration, which I want to get loaded, when the main app loads.
Apparently, this does not happen out of the box (by just including the module to the main app). What else do I need to do, to get the module configuration class also get loaded by the main app?
The easiest way is to scan the package that the #Configuration class is in.
#ComponentScan("com.acme.otherJar.config")
or to just load it as a spring bean:
#Bean
public MyConfig myConfig() {
MyConfig myConfig = new MyConfig ();
return myConfig;
}
Where MyConfig is something like:
#Configuration
public class MyConfig {
// various #Bean definitions ...
}
See docs
#ComponentScan annotation will scan all classes with #Compoment or #Configuration annotation.
Then spring ioc will add them all to spring controlled beans.
If you want to only add specific configurations, you can use #import annotation.
example:
#Configuration
#Import(NameOfTheConfigurationYouWantToImport.class)
public class Config {
}
#Import Annotation Doc
I'm working with spring-boot on a multi module project (maven). Each module has it's own #Configuration class. Basically I do have the following layout
Module foo-embedded (runs just calls the SpringApplication.run()) method:
#Configuration
#EnableAutoConfiguration
#ComponentScan("de.foobar.rootpackage")
#Import({ApplicationConfig.class, RepositoryConfig.class, SecurityConfig.class})
public class FooApplication {
public static void main(String[] args) throws Exception {
SpringApplication.run(FooApplication.class, args);
}
}
Module foo-common (contains all beans and spring-data-jpa initialization config)
#Configuration
#EnableJpaRepositories
#EnableTransactionManagement(entityManagerFactoryRef="entityManagerFactory")
public class RepositoryConfig {
#Bean(destroyMethod = "shutdown")
public DataSource getDataSource() {
// returning a Hikari CP here
}
#Bean(name = "entityManagerFactory") // overriding spring boots default
public EntityManagerFactory getEntityManagerFactory() {
// returning a new LocalEntityManagerFactoryBean here
}
}
Module foo-security (containing spring-securiy configuration and related domain classes), which has a maven dependency on foo-common
#Configuration
#EnableWebSecurity
#EnableGlobalMethodSecurity(prePostEnabled = true)
public class SecurityConfig extends WebSecurityConfigurerAdapter {
// configuring HTTP security and defining my UserDetailsService Bean
}
When I start the application using the FooApplication class, everything works as expected. The above mentioned UserDetailsServiceImpl get's autowired with my UserRepository which is being created through the #EnableJpaRepositories annotation.
Since I want to write some integration tests I've added a test clss to one of my modules.
Module foo-media (containing some domain related stuff plus test cases for that module)
#RunWith(SpringJUnit4ClassRunner.class)
#SpringApplicationConfiguration(classes = {RepositoryConfig.class, SecurityConfig.class})
#WebAppConfiguration
#IntegrationTest
public class DirectoryIntegrationTest {
// my test code
}
When I run the test it seems that the SecurityConfiguration get's loaded before the RepositoryConfig.class does. Since the security config defined the UserServiceImpl which must be autowired, the test fails to start with a
NoSuchBeanDefinitionException telling me: No qualifying bean of type [com.foo.rootpackage.security.repository.UserRepository]
I already tried to add #DependsOn("UserRepository") at the bean definition of UserDetailsService, telling me that spring can't find a bean by that name.
Any hints or help would be greatly appreciated! Thanks in advance!
---- EDIT (since I was asked to provide more code) ----
For testing I do not use the actual RepositoryConfig.class, but have a TestRepositoryConfig.class in the common module. Looking like this
#Configuration
#EnableTransactionManagement
#EnableJpaRepositories(entityManagerFactoryRef = "entityManagerFactory", basePackages = "de.foobar.rootpackage")
public class TestRepositoryConfig extends RepositoryConfig {
#Bean
#Override
public DataSource getDataSource() {
// returning the ds for testing
}
}
You can use #Order annotation on your configuration classes to define load ordering. But it's strange because Spring should resolve proper order - so please check if you property inject UserRepository in UserDetailsService
So I was able to solve this. As it pointed out it had nothing to do with the loading order of the configuration classes (which was my first thought).
As you may notice, the only Configuration that had a #ComponentScan annotation was the FooApplication.class
Spring was not able to find the Repositories, as it didn't know where to look for. Providing the basePackages attribute like this:
#EnableJpaRepositories(basePackages = "de.foobar.rootpackage")
at the TestRepositoryConfig.class did the trick here.