--Appconfig.java
#Configuration
public class AppConfig {
#Bean(name="helloBean")
public HelloWorld helloWorld() {
return new HelloWorldImpl();
}
}
--interface.java
public interface HelloWorld {
void printHelloWorld(String msg);
}
--ipml.java
public class HelloWorldImpl implements HelloWorld {
public void printHelloWorld(String msg) {
System.out.println("Hello! : " + msg);
--
}
--App.java
public class App {
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new
new AnnotationConfigApplicationContext(AppConfig.class);
HelloWorld obj = (HelloWorld) context.getBean(HelloWorldImpl.class);
obj.printHelloWorld("Spring3 Java Config");
}
}
My program can works, but my question is why I don't need to add #componentScan in Appconfig.java .
It seems to #Configuration and #Bean can be found by Spring whithout using #componentScan.
I thought if you want to use #annotation ,you must use #componentScan or
context:component-scan(xml),
am I right?
#ComponentScan allows spring to auto scan all your components with #Component annotated. Spring uses the base-package attribute, which indicates where to find components.
#Configuration is meta annotated with #Component, which marks it eligible for classpath scanning.
#Configuration (AppConfig class) is registered when you use
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
#Bean doesn't need #ComponentScan as all these beans are created explicitly when spring encounters this annotation.
Related
I use Spring 4.2.8 and I do have the service class below. If this class has the name ScheduleEmailCreateAndSendServiceImpl than everything works fine (method generalEmailMessage is invoked at start time in order to create the Spring Bean)
If I rename this class to EmailCreateAndSendServiceImpl than method generalEmailMessage will not be invoked at start time - does anyone know why?
#Service("emailCreateAndSendService")
public class ScheduleEmailCreateAndSendServiceImpl extends AbstractService
implements EmailService {
protected EmailMessage generalMessage;
#Override
public void createAndSendMessage(String receiver, boolean emailActive, Object[] values) throws BusinessException {
// create and send email
}
#Bean
public EmailMessage generalEmailMessage() {
this.generalMessage = new GeneralEmailInformationMessage();
return generalMessage;
}
}
[EDIT]
with this code it is the same
#Configuration
public #Data class ScheduleGeneralEmailConfiguration {
protected EmailMessage generalMessage;
public ScheduleGeneralEmailConfiguration() {
System.out.println("asdf");
}
#Bean
public EmailMessage generalEmailMessage() {
this.generalMessage = new GeneralEmailInformationMessage();
return generalMessage;
}
}
#Bean annotated methods should be in #Configuration annotated class.
You can also put the #Bean annotated methods in the main class of the Spring Boot application annotated with #SpringBootApplication which encapsulates #Configuration, #EnableAutoConfiguration, and #ComponentScan annotations.
Make sure your #Configuration annotated class is placed in the same package or sub package of the Spring Boot Application class
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).
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
I'm using JavaConfig to manage and wire Spring beans into my Java app. The Java application is a main method - and basically runs as a batch job, invoked via a bash file. Is there a way that I can use a different (test) config in my main method?
public static void main(String[] args) {
final ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig.class);
// do Stuff
}
I have used the following annotations successfully before in my test classes:
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes = { TestConfig.class })
, but this does not work for "main" applications. Short of passing in the Spring context to use as an argument, not sure what I can do here. Thanks
You should be able to use profiles in your actual config class to do what you want as well.
By setting the desired Profile you can "inject" the different beans you want.
Your ApplicationConfig might look like:
#Configuration
#Import({
JndiDataConfig.class,
TestDataConfig.class,
)
public class ApplicationConfig {
...
where TestDataConfig looks (in part) like:
#Configuration
#Profile("test")
public class TestDataConfig {
#Bean
public DataSource dataSource() {
return new EmbeddedDatabaseBuilder()
.setType(EmbeddedDatabaseType.HSQL)
.addScript("classpath:com/bank/config/sql/schema.sql")
.addScript("classpath:com/bank/config/sql/test-data.sql")
.build();
}
}
and where JndiDataConfig looks like:
#Configuration
#Profile("production")
public class JndiDataConfig {
#Bean
public DataSource dataSource() throws Exception {
Context ctx = new InitialContext();
return (DataSource) ctx.lookup("java:comp/env/jdbc/datasource");
}
}
I have following set up for my Spring Application Context.
#Configuration
public class RmiContext {
#Bean
public RmiProxyFactoryBean service() {
RmiProxyFactoryBean rmiProxy = new RmiProxyFactoryBean();
rmiProxy.setServiceUrl("rmi://127.0.1.1:1099/Service");
rmiProxy.setServiceInterface(Service.class);
return rmiProxy;
}
}
#Configuration
public class LocalContext {
#Bean
public Controller Controller() {
return new ControllerImpl();
}
}
#Configuration
#Import({RmiContext.class, LocalContext.class})
public class MainContext {
}
The above setup works fine, but I want to enable #ComponentScan annotating Controllers with #Component as there are many Controllers in my application which is tedious when declared one by one using #Bean.
#Configuration
#ComponentScan(basePackageClasses = {Controller.class})
public class LocalContext {
/* ... */
}
The problem is that when I do #ComponentScan(basePackageClasses = {Controller.class}), the previously fine working RmiProxyFactoryBean are not recognized or can't be created.
So, How do I configure my MainContext so that both beans via RMI and local beans are created?
#Configuration is also a candidate for component scan, so you can scan all the beans in RmiContext and all controllers in your controller package by:
#Configuration
#ComponentScan(basePackages = {"org.example.controllers", "package.of.RmiContext"})
public class MainContext {
}
--edit--
#Configuration is a candidate for component scan, here is the test case that works in my pc:
package scan.controllers;
#Controller
public class ExampleController {
}
package scan;
public interface RMIService {
}
package scan;
#Configuration
public class RmiContext {
#Bean
public RmiProxyFactoryBean service() {
RmiProxyFactoryBean rmiProxy = new RmiProxyFactoryBean();
rmiProxy.setServiceUrl("rmi://127.0.1.1:1099/Service");
rmiProxy.setServiceInterface(RMIService.class);
rmiProxy.setLookupStubOnStartup(false);
return rmiProxy;
}
}
package scan;
#Configuration
//MainContext will auto scan RmiContext in package scan and all controllers in package scan.controllers
#ComponentScan(basePackages = {"scan", "scan.controllers"})
public class MainContext {
}
package scan;
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes={MainContext.class})
public class TestContext {
#Autowired private RMIService rmi;
#Autowired private ExampleController controller;
#Test
public void test() {
//both controller and rmi service are autowired as expected
assertNotNull(controller);
assertNotNull(rmi);
}
}
May be you could try using the base packages of your classes (RMI, Controller):
#ComponentScan(basePackages = {"your controller package", "your rmi package"})
If the RMI classes package is different than controller then they will fail to instantiate by spring.
If I understand you correctly, you use "#ComponentScan(basePackageClasses" but it is not detecting and registering your spring beans?
I had the same issue a few minutes ago. I did not give up and tried all funny guesses. One guess did it.
I had to add an XML component-scan entry in XML. I just put a dummy package there, like below:
component-scan base-package="dummy.filler.to.enable.component.scan"
It seems that the component-scan in XML enables the #ComponentScan.
[Late Edit: I noticed, my spring xml schema is spring 2.5. Anyway, I dont know if this matters. Best Regards.]