I have a simple SpringBootApplication that sets up JPA and defines some Beans.
#SpringBootApplication
public class AnalysisApplication {
public static void main(String[] args) {
SpringApplication.run(AnalysisApplication.class, args);
}
#Autowired
SoftwareArchiveRepository swaRepository;
#Bean
SoftwareArchiveService swaService() {
return new SoftwareArchiveService(swaRepository);
}
#Bean
PlatformService platformService(#Autowired PlatformRepository platformRepository) {
return new JpaPlatformService(platformRepository);
}
// More Bean definitions omitted
}
I now want to use this context in a couple of classes that perform one time setup for my application that I will call manually. Although they use the defined beans, they are not really part of the application - basically I want to perform a one-off data load exercise.
public class DatabaseLoader {
ApplicationContext context;
public static void main(String[] args) {
DatabaseLoader loader = new DatabaseLoader();
loader.run();
}
private void run() {
context = ??????
PlatformService service = context.getBean("platformService");
// etc etc
}
What do I need to do to intialize a SpringBootApplication context so that all the SpringBoot autoconfiguration happens without actually calling SpringApplication.run(AnalysisApplication.class, args);
Related
I am trying to get the value of a property
hello.world=Hello World
in MainApp class
#SpringBootApplication
public class MainApp {
public static void main(String[] args) {
SpringApplication.run(MainApp.class, args);
}
This didn't work as its the main method.
#Value("${hello.world}")
public static String helloWorld;
Maybe its possible to load by
Properties prop = new Properties();
// load a properties file
prop.load(new FileInputStream(filePath));
Is there any other better way to get the properties using Spring in the main method of SpringBoot before SpringApplication.run
ConfigurableApplicationContext ctx =
SpringApplication.run(MainApp.class, args);
String str = ctx.getEnvironment().getProperty("some.prop");
System.out.println("=>>>> " + str);
You have declared the variable helloWorld as static. Hence you need to use Setter Injection and not Field Injection.
Injecting a static non-final field is a bad practice. Hence Spring doesn't allow it. But you can do a workaround like this.
public static String helloWorld;
#Value("${hello.world}")
public void setHelloWorld(String someStr) {
helloWorld = someStr
}
You can access this variable helloWorld at any point in the class, if its any other class. But if you want to do it in the main class. You can access the variable only after this line
SpringApplication.run(MainApp.class, args);)
i.e only after the application has started.
Don't do this. Its better to use CommandLineRunner.
Thanks to this you can have a non static method that Spring Boot will run for you automatically:
#SpringBootApplication
public class SimulatorApplication implements CommandLineRunner {
#Value("${my-value}")
private myValue;
public static void main(String[] args) {
SpringApplication.run(SimulatorApplication.class, args);
}
#Override
public void run(String... args) throws Exception {
// here you can access my-value
}
}
#SpringBootApplication
public class MainApp {
public static void main(String[] args) {
SpringApplication springApplication = new SpringApplication(MainApp.class);
springApplication.addListeners(new VersionLogger());
springApplication.run(args);
}
// The VersionLogger Class
public class VersionLogger implements ApplicationListener<ApplicationEnvironmentPreparedEvent>{
#Override
public void onApplicationEvent(ApplicationEnvironmentPreparedEvent applicationEvent) {
String helloWorld = applicationEvent.getEnvironment().getProperty("hello.world");
}
}
ApplicationEnvironmentPreparedEvent
Event published when a SpringApplication is starting up and the Environment is first available for inspection and modification.
ApplicationContext applicationContext = SpringApplication.run(Application.class, args);
String applicationPropertyVersion=applicationContext.getEnvironment().getProperty("application.property.version");
LOGGER.info("RELEASE CODE VERSION {} and applicationProperty Version {} ", LcoBuildVersion.version,
applicationPropertyVersion);
We can't read values into static fields . Here is the explanation gives a better insight How to assign a value from application.properties to a static variable?
Are there ways to override properties of DefaultListableBeanFactory in Spring Boot application?
For example, I want to set the DefaultListableBeanFactory.allowBeanDefinitionOverriding property to false.
EDIT
Use case.
I have pretty plain class:
#Data
#AllArgsConstructor
class MyTempComponent {
private String value;
}
Which I want use as #Bean in my application but this bean can be defined several times, for example:
#Configuration
class TestConfiguration1 {
#Bean
MyTempComponent myTempComponent() {
return new MyTempComponent("Value 1");
}
}
#Configuration
class TestConfiguration2 {
#Bean
MyTempComponent myTempComponent() {
return new MyTempComponent("Value 2");
}
}
Also there is a consumer of that bean:
#Component
class TestConfiguration3 {
private MyTempComponent myTempComponent;
#Autowired
public TestConfiguration3(MyTempComponent myTempComponent) {
this.myTempComponent = myTempComponent;
}
#PostConstruct
public void print() {
System.out.println(this.myTempComponent.getValue());
}
}
When an application starts it prints "Value 2" message, i.e. initializes myTempComponent bean from TestConfiguration2.
I want to prohibit creation of that bean (and any other beans) if there are two or more candidates.
As I realized I can reach this goal via setting DefaultListableBeanFactory.allowBeanDefinitionOverriding to false.
But how to set this property in Spring Boot application? Could you provide an example please?
You can set
private static class CustomAppCtxInitializer implements ApplicationContextInitializer<GenericApplicationContext> {
#Override
public void initialize(GenericApplicationContext applicationContext) {
applicationContext
.getDefaultListableBeanFactory()
.setAllowBeanDefinitionOverriding(false);
}
}
and then have
public static void main(String[] args) {
try {
final SpringApplication springApplication = new SpringApplication(Application.class);
springApplication.addInitializers(new CustomAppCtxInitializer());
I am trying to get the value of a property
hello.world=Hello World
in MainApp class
#SpringBootApplication
public class MainApp {
public static void main(String[] args) {
SpringApplication.run(MainApp.class, args);
}
This didn't work as its the main method.
#Value("${hello.world}")
public static String helloWorld;
Maybe its possible to load by
Properties prop = new Properties();
// load a properties file
prop.load(new FileInputStream(filePath));
Is there any other better way to get the properties using Spring in the main method of SpringBoot before SpringApplication.run
ConfigurableApplicationContext ctx =
SpringApplication.run(MainApp.class, args);
String str = ctx.getEnvironment().getProperty("some.prop");
System.out.println("=>>>> " + str);
You have declared the variable helloWorld as static. Hence you need to use Setter Injection and not Field Injection.
Injecting a static non-final field is a bad practice. Hence Spring doesn't allow it. But you can do a workaround like this.
public static String helloWorld;
#Value("${hello.world}")
public void setHelloWorld(String someStr) {
helloWorld = someStr
}
You can access this variable helloWorld at any point in the class, if its any other class. But if you want to do it in the main class. You can access the variable only after this line
SpringApplication.run(MainApp.class, args);)
i.e only after the application has started.
Don't do this. Its better to use CommandLineRunner.
Thanks to this you can have a non static method that Spring Boot will run for you automatically:
#SpringBootApplication
public class SimulatorApplication implements CommandLineRunner {
#Value("${my-value}")
private myValue;
public static void main(String[] args) {
SpringApplication.run(SimulatorApplication.class, args);
}
#Override
public void run(String... args) throws Exception {
// here you can access my-value
}
}
#SpringBootApplication
public class MainApp {
public static void main(String[] args) {
SpringApplication springApplication = new SpringApplication(MainApp.class);
springApplication.addListeners(new VersionLogger());
springApplication.run(args);
}
// The VersionLogger Class
public class VersionLogger implements ApplicationListener<ApplicationEnvironmentPreparedEvent>{
#Override
public void onApplicationEvent(ApplicationEnvironmentPreparedEvent applicationEvent) {
String helloWorld = applicationEvent.getEnvironment().getProperty("hello.world");
}
}
ApplicationEnvironmentPreparedEvent
Event published when a SpringApplication is starting up and the Environment is first available for inspection and modification.
ApplicationContext applicationContext = SpringApplication.run(Application.class, args);
String applicationPropertyVersion=applicationContext.getEnvironment().getProperty("application.property.version");
LOGGER.info("RELEASE CODE VERSION {} and applicationProperty Version {} ", LcoBuildVersion.version,
applicationPropertyVersion);
We can't read values into static fields . Here is the explanation gives a better insight How to assign a value from application.properties to a static variable?
I want to combine two libraries - JavaFx and Spring Boot, thus I need to have an instance of ApplicationContext in my start() method in main class:
Main class:
#SpringBootApplication
public class JavaFXandSpringBootTestApplication extends Application{
#Autowired
ApplicationContext ctx;
public static void main(String[] args) {
SpringApplication.run(JavaFXandSpringBootTestApplication.class, args);
launch();
}
#Override
public void start(Stage stage) throws Exception {
FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/LogIn.fxml"));
loader.setController(ctx.getBean(LogInController.class)); // HERE OCCURES ERROR
Scene scene = new Scene((Parent)loader.load());
stage.setScene(scene);
stage.show();
}
}
Controller class:
#Component
public class LogInController {
}
As I have read the documentary #SpringBootApplication enables auto detect of Components and under the hood is also annotating the class with #Configuration.
So now, why am i reciving a NullPointerException in commended line? It's because that ctx isn't injected properly, but why? What am i doing wrong?
You can't inject the ApplicationContext (or anything else) into the Application instance on which start() is invoked: that instance of Application is created for you by JavaFX, not by Spring. Since it's not a spring-managed object, there is no mechanism for Spring to inject anything into it.
Move the call to SpringApplication.run() to the init() method, where you can simply assign the context directly. Also, imho a better way to let the controllers be Spring-managed is to tell the FXMLLoader to create controllers via Spring, which you can do with a controller factory. See Dependency Injection and JavaFX.
#SpringBootApplication
public class JavaFXandSpringBootTestApplication extends Application{
private ApplicationContext ctx;
public static void main(String[] args) {
launch(args);
}
#Override
public void init() {
String[] args = getParameters().getRaw().toArray(new String[0]);
ctx = SpringApplication.run(JavaFXandSpringBootTestApplication.class, args);
}
#Override
public void start(Stage stage) throws Exception {
FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/LogIn.fxml"));
loader.setControllerFactory(ctx::getBean);
// or, if you prefer,
// loader.setController(ctx.getBean(LoginController.class));
// though the controller factory approach lets you use `fx:controller` as usual.
Scene scene = new Scene((Parent)loader.load());
stage.setScene(scene);
stage.show();
}
}
What is the right way for creating test data upon server startup and inserting them into the database (I'm using a JPA/JDBC backed Postgres instance).
Preferably in form of creating Entities and having them persisted through a Repository interface rather than writing plain SQL code. Something like RoR's Rake db:seed helper.
If the framework exposes a hook for doing stuff when all the beans have been injected and the database is ready, that could also work.
You can catch ApplicationReadyEvent then insert demo data, for example:
#Component
public class DemoData {
#Autowired
private final EntityRepository repo;
#EventListener
public void appReady(ApplicationReadyEvent event) {
repo.save(new Entity(...));
}
}
Or you can implement CommandLineRunner or ApplicationRunner, to load demo data when an application is fully started:
#Component
public class DemoData implements CommandLineRunner {
#Autowired
private final EntityRepository repo;
#Override
public void run(String...args) throws Exception {
repo.save(new Entity(...));
}
}
#Component
public class DemoData implements ApplicationRunner {
#Autowired
private final EntityRepository repo;
#Override
public void run(ApplicationArguments args) throws Exception {
repo.save(new Entity(...));
}
}
Or even implement them like a Bean right in your Application (or other 'config') class:
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public CommandLineRunner demoData(EntityRepository repo) {
return args -> {
repo.save(new Entity(...));
}
}
}
From Spring documentation: http://docs.spring.io/spring-boot/docs/1.5.4.RELEASE/reference/htmlsingle/#howto-database-initialization
Initialize a database using Hibernate
A file named import.sql in the root of the classpath will be executed on startup if Hibernate creates the schema from scratch (that is if the ddl-auto property is set to create or create-drop). This can be useful for demos and for testing if you are careful, but probably not something you want to be on the classpath in production. It is a Hibernate feature (nothing to do with Spring).
You can do like this
#SpringBootApplication
public class H2Application {
public static void main(String[] args) {
SpringApplication.run(H2Application.class, args);
}
#Bean
CommandLineRunner init (StudentRepo studentRepo){
return args -> {
List<String> names = Arrays.asList("udara", "sampath");
names.forEach(name -> studentRepo.save(new Student(name)));
};
}
}