This is based on https://spring.io/guides/gs/accessing-data-jpa/
I tried to move demo() in a different class in a different package (Application still on top of the filesystem hierarchy)
How do I make demo() run when i boot the project?
Application.java
package com.company.app
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class);
}
}
CommandLineRunner.java
package com.company.app.runner
public class Test {
#Bean
public CommandLineRunner demo() {
System.out.print("Run 1");
return (args) -> {
System.out.print("Run 2");
};
}
}
Add #Configuration to the Test class so that it is picked up when the classpath is scanned.
I haven't seen a Lambda for the CommandLineRunner before. Very nifty and saves having to create a class that specifically implements the CommandLineRunner.
Otherwise, you could implement CommandLineRunner to test and annotate as #Component.
#Component
public class ApplicationLoader implements CommandLineRunner {
#Override
public void run(String... strings) throws Exception {
System.out.print("Run 2");
}
}
* Update *
Answering the question in the comment with this update as I have more room to type...
#SpringBootApplication composes those other annotations as you indicated but those annotations are only applied to the specific class that it is defined on. The #Configuration annotation is telling Spring that the class defines beans that should be managed by the application context. The #ComponentScan tells spring to look through the classpath for classes that have specific annotations (e.g. #Component, #Service, #Configuration) and then act on those classes based on the type of annotation. the #EnableAutoConfiguration is the magic that loads appropriate beans based on the project dependencies (e.g. if mongo driver is on the classpath then create a MongoTemplate).
Related
I'm refactoring an existing application to use Spring Boot. The issues I've faced here are generally of the type "why is this not working anymore".
I have three packages
- nl.myproject.boot
- nl.myproject
- nl.myproject.rest
My current problem is that all #Services that I #Inject in a #RESTController resolve to null when a method is called on them.
The service and dao are part of the nl.myproject package and the reason it's not nl.myproject.core is a legacy issue.
A related issue is that my #Configuration components don't seem to be loaded through #ComponentScan and I have to import them manually. I also had to exclude Test configuration to prevent Test configs from being loaded, which also seemed weird.
Internal calls from the service layer during start up, such as data preparation works normally. Any such manager is also #Injected. This is just to say that any of the typical injection mistakes such as manual instantiation or injecting a class instead of an interface don't apply.
I'd also be grateful for debugging tips. My Java has gotten a little rusty.
#EnableAutoConfiguration
#ComponentScan(basePackages= {
"nl.myproject",
"nl.myproject.boot",
"nl.myproject.dao",
"nl.myproject.service",
"nl.myproject.webapp"},
excludeFilters= {
#ComponentScan.Filter(type=FilterType.REGEX,pattern={".*Test.*"}),
#ComponentScan.Filter(type=FilterType.REGEX,pattern={".*AppConfig"})
}
)
#Configuration
#EnableConfigurationProperties
#Import({
JPAConfig.class,
RestConfig.class,
BootConfig.class
})
public class Startup {
public static void main(String[] args) throws Exception {
SpringApplication.run(Startup.class, args);
}
}
#RestController
#RequestMapping(value="/json/tags")
public class JsonTagController extends JsonBaseController {
#Inject
TagManager tagMgr;
public interface TagManager extends BaseManager<Tag,Long> {
[...]
}
#Service("tagManager")
public class TagManagerImpl extends BaseManagerImpl<Tag, Long> implements
TagManager {
#Inject
TagDao dao;
[...]
#Inject is a annotation specified by JSR-330 (standard) whereas #Autowired is annotation specified by Spring.
They just do the same dependency injection. You can both of them in the same code.
Just the modification (separation of the concerns) you need :
public interface TagManager {
[...]
}
#Service
public class TagManagerImpl implements TagManager {
#Inject
private TagDao dao;
// inject that service rather than extending
#Inject
private BaseManager<Tag,Long> baseManager;
}
public interface BaseManager<Tag,Long> {
[...]
}
#Service
public class BaseManagerImpl<Tag,Long> implements BaseManager<Tag,Long> {
....
}
Just one thing you do for checking, just modify to basePackages= {"nl.myproject"} - just provide only base package, that's enough for spring to scan the components in every package.
Hope this may help :)
I am developing a springboot app that has dependency on another springboot application. I want to include Most beans in the parent springboot app but one.
How can I exclude one springboot bean that the parent package has scanned without touching the ParentApplication class?
Ways I have tried but doesn't work:
1: using exclude filtering in my application class to filter out the particular bean class.
2: I also tried to exclude both the bean class and the parent configuration class.
3: add DisposableBean interface to the bean class I want to exclude and destroy it in run time.
below are my application starter configuration class and parent one.
my MyApplication.class:
package com.myapp;
#ComponentScan(
basePackages = {"com.parent",{my own packages..}},
excludeFilters= {
#ComponentScan.Filter(type=FilterType.ASSIGNABLE_TYPE, value= {TheClassToExclude.class}),
#ComponentScan.Filter(type=FilterType.ASSIGNABLE_TYPE, value= {ParentApplication.class})}
)
#SpringBootApplication(exclude=ParentApplication.class)
public class MyApplication{
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
#PostConstruct
public void init() {
System.out.println("App is initialized.");
}
}
my ParentApplication.class
package com.parent;
#EnableRetry
#EnableScheduling
#SpringBootApplication(exclude = { HibernateJpaAutoConfiguration.class })
#ComponentScan(basePackages = {all the base package including the TheClassToExclude}
#PropertySource({all resources})
public class ParentApplication {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#PostConstruct
public void haha() {
System.out.println("configuration class created");
}
The console prints out: "configuration class created", so ParentApplication is initiated by springboot for some reason, so is the Class I want to exclude.
just for reference - I think that since both classes are annotated with #SpringBootApplication, thus are both #Configuration classes and will take part in the automatic Spring component scan - and it is not clear which of this classes will be scanned first in order to "exclude" the other one - unless... you explicitly specify the entry point, and thus, the first SpringBootApplication class to load like here
You can see which classes get instantiated by Spring component scanning and in what order by setting logging.level.org.springframework=DEBUG in application.properties
I have the following classes:
#ComponentScan
public class CDPlayerConfig {
#Autowired
private static CompactDisc cd;
public static void main(String[] args) {
ApplicationContext context = new AnnotationConfigApplicationContext(CDPlayerConfig.class);
CompactDisc cd = context.getBean(CompactDisc.class);
System.out.println(cd);
}
}
public interface CompactDisc {
void play();
}
#Component
public class SgtPeppers implements CompactDisc {
public void play() {
System.out.println("play song....");
}
}
When I run the class CDPlayerConfig, the program runs successfully. However, if I remove the ComponentScan annotation to CompactDisc interface or SgtPeppers I get the following error:
Exception in thread "main"
org.springframework.beans.factory.NoSuchBeanDefinitionException: No
qualifying bean of type 'CompactDisc' available
I think that ComponentScan annotation marks the package where Spring looks for beans. CDPlayerConfig, CompactDisc and SgtPeppers are all placed in the same package, so allegedly moving ComponentScan annotation from one class to another should not make a difference.
If so, why do I get an error?
For #ComponentScan to work you have to "tell" spring where to search, or it must find it with help of other, already loaded, #ComponentScan annotated class (your class must be then annotated also with #Component, #Configuration etc. so it could be found).
In your case, you register application context in the first line of main method - you have specified there to load CDPlayerConfig.class which is #ComponentScan annotated so now spring can automatically find other beans in the package:
ApplicationContext context =
new AnnotationConfigApplicationContext(CDPlayerConfig.class);
If you want to move #ComponentScan to another class, you have to change class registered in AnnotationConfigApplicationContext to some #ComponentScan annotated class:
SgtPeppers:
#Component
#ComponentScan
public class SgtPeppers implements CompactDisc {
(...)
Main in CDPlayerConfig:
ApplicationContext context =
new AnnotationConfigApplicationContext(SgtPeppers.class);
Note you should register context from concrete classes (not interfaces).
Also, above sample would work even without #ComponentScan annotation on SgtPeppers, but then beans defined in other classes from the package wouldn't be found.
I am trying to save data on gemfire using crud repository. I have created one operation class to call save method of repository but at autowired instance I am getting null pointer exception. Below is my code:
public interface GeodeRepository extends CrudRepository<KeyValueBean, String> {
#Override
public KeyValueBean findOne(String name);
#Override
public <S extends KeyValueBean> Iterable<S> save(Iterable<S> entities);
}
#EnableGemfireRepositories(basePackageClasses = GeodeRepository.class)
#EnableAutoConfiguration
#Configuration
public class Operations {
#Autowired
private GeodeRepository repository;
public void saveKeyValueData(KeyValueBean keyValueBean) {
System.out.println("Repository is : " + repository);
repository.save(Arrays.asList(keyValueBean)); // <--- i am getting
// repository as null so
// getting null pointer
// exception
}
}
When we #Autowired any class make sure, you have declared that class as a #Component.
for example:
#Component
public class Operations {
#Autowired
private GeodeRepository repository;
public void saveKeyValueData(KeyValueBean keyValueBean) {
System.out.println("Repository is : " + repository);
repository.save(Arrays.asList(keyValueBean));
}
}
and try using #Autowired to Operation class to your class
in which class your are calling your saveKeyValueData() method.
So, what is not apparent from your example is how you "bootstrap" your application and it's features (e.g. Repositories) into action.
It is not simply enough to add the Spring #Configuration, Spring Boot's #EnableAutoConfiguration and SD GemFire's #EnableGemfireRepositories annotations and expect everything to be auto-configured and wired up successfully. I.e. you need a bootstrapping mechanism, like Spring Boot, especially if you are using the #EnableAutoConfiguration annotation.
For example...
import org.springframework.boot.SpringApplication;
...
class MyApplication {
public static void main(String[] args) {
SpringApplication.run(Operations.class, args);
}
}
Now, you could remove the #EnableAutoConfiguration from your Operations class and add the #SpringBootApplication to the MyApplication class, like so...
#SpringBootApplication
class MyApplication {
...
}
#SpringBootAppliation combines together Spring's #Configuration with Spring Boot's #EnableAutoConfiguration, along with many other useful meta-annotations, like Spring's #ComponentScan, enabling all sorts of magic to happen.
But, if you are not using Spring Boot, you can always bootstrap you application with the AnnotationConfigApplicationContext, like so..
class MyApplication
public static void main(String[] args) {
AnnotationConfigApplicationContext applicationContext =
new AnnotationConfigApplicationContext(Operations.class);
applicationContext.registerShutdownHook();
}
}
This is essentially what the Spring Boot, SpringApplication class does for you anyway.
If you are developing a Web application, then of course you can specify the type of ApplicationContext created since you are using Java config, for instance. See here for more details.
Hope this helps!
Cheers,
John
#Autowired
Environment env;
#Value("${jdbcConnectionString}")
private String jdbcConnectionString;
The above works automagically in certain classes, however is null in similar classes in same package and with same annotations #Configuration/#Component.
I am trying to find out the proper approach to understand what spring does when while configuring various artifacts.
I am able to run stuff every now and then but any good resource to understand the magic is well appreciated.
PS. I am only interested in java-config based approach now.
Working :
package a.b.c;
#Configuration
public class AppConfig {
#Autowired
Environment env;
package a.b.d;
#Configuration
#EnableBatchProcessing
public class JobConfiguration {
#Autowired
private Environment env;
package a.b.L;
public class BatchJobListener implements Ordered, JobExecutionListener {
#Autowired
public Environment env;
Not working inside
package a.b.u
Tried to annotate classes with #Component/#Configuration
In order to autowire a bean, you need first to defined it in a Context.
#Configuration
public class ConfigOne {
#Bean
public String myBean(){
return "my bean";
}
}
The bean that you want to inject and the bean where the bean will be injected need to be in the same context. You can do it with:
JavaConfigApplicationContext context =
new JavaConfigApplicationContext(ConfigOne.class, ConfigTwo.class);
Or you can use #import to import one configuration class into another.
#Configuration
#Import(ConfigTwo.class)
public class ConfigOne {
UPDATE
What I meant was that probably you're not making the configuration in the ringht way. So all your beans where you're injecting the enviroment are not in the same context.
However, if you have configured well everything, it's possible that some classes are loading before enviroment. In this case you can use EnvironmentAware
#Configuration
#PropertySource("classpath:myProperties.properties")
public class MyConfiguration implements EnvironmentAware {
private Environment environment;
#Override
public void setEnvironment(final Environment environment) {
this.environment = environment;
}
public void myMethod() {
final String myPropertyValue = environment.getProperty("myProperty");
// ...
}
}
In your main class where you are initializing the spring boot application, do you have similar configuration:
#Configuration
#SpringBootApplication
#EnableAutoConfiguration
#ComponentScan("a.b") //Note that this scans the components where you have configured spring container backed objects
#PropertySource({
"classpath:someProperty1.properties",
"classpath:someProperty2.properties"
})
public class Main{
public static void main(String[] args) {
SpringApplication.run(Main.class, args);
}
}
What this basically does is, it tells spring that this is a configuration class, and indicates this configuration class that it also triggers auto-configuration and component scanning (scan only these specific packages (a.b) and check if there are any annotations present for automatic bean detection, like: #Component, #Service, #Controller, #Repository). On detecting any class which have these stereotypes spring would create object(s) depending on the configuration. On creating these objects one may have autowired some objects or one could refer to some property defined in properties file. The config #PropertySource does this.
The package declaration in #ComponentScan should be the base package.