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();
}
}
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?
I am trying to create a Spring boot application with JFrame. I can see my beans in applicationContext but they are not getting autowired. I am unable to find the reason for this issue. Can someone help me with this?
Here is the code:
JavauiApplication - it is showing both userManager and userNameRepository is beans
#SpringBootApplication
public class JavauiApplication implements CommandLineRunner {
#Autowired
private ApplicationContext appContext;
public static void main(String[] args) {
new SpringApplicationBuilder(JavauiApplication.class).headless(false).run(args);
java.awt.EventQueue.invokeLater(() -> new InputNameForm().setVisible(true));
}
#Override
public void run(String... args) throws Exception {
String[] beans = appContext.getBeanDefinitionNames();
Arrays.sort(beans);
for (String bean : beans) {
System.out.println(bean);
}
}
}
InputNameForm.java -> userManager coming null
#Component
public class InputNameForm extends javax.swing.JFrame {
/**
* Creates new form InputNameForm
*/
public InputNameForm() {
initComponents();
}
#Autowired
UserManager userManager;
private void submitButtonActionPerformed(java.awt.event.ActionEvent evt) {
userManager.setName(firstName.getText(), lastName.getText());
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(InputNameForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new InputNameForm().setVisible(true);
}
});
}
// Variables declaration - do not modify//GEN-BEGIN:variables
private javax.swing.JTextField firstName;
private javax.swing.JLabel firstNameLabel;
private javax.swing.JTextField lastName;
private javax.swing.JLabel lastNameLabel;
private javax.swing.JButton submitButton;
// End of variables declaration//GEN-END:variables
}
UserManager.java -> userNameRepository is coming null
#Component
public class UserManager {
#Autowired
UserNameRepository userNameRepository;
public void setName(String firstName, String lastName) {
userNameRepository.save(new UserName(firstName, lastName));
System.out.println(userNameRepository.findAllByFirstName(firstName));
}
}
It's a very common problem and it occurs because newcomers don't understand how the IoC container works.
Firstly, BeanDefinitionReader reads metadata about your beans from XML, Annotations(#Component, #Service etc), JavaConfig or Groovy script.
There are several BeanPostProcessor's which is responsible for reading all of these Spring annotation you're writing(#Autowired etc).
BeanFactory creates all BeanPostProcessor's then it creates all of your beans.
What happen if you create your bean with #Autowired dependencies via new operator? Nothing, because it isn't actually a bean. The object you created isn't related to IoC container. You may have the bean already in your ApplicationContext if you marked it with #Component(for example) but the object which was created via new operator wont be processed by Spring(annotations won't work).
Hope this helps.
PS: The lifecycle is simplified.
I had the same problem few days ago. What I undertood was that GUI builders like the one that comes with netbeans will automatically create components using new keyword. This means that those components won't be manage by spring. The code usually loks like this:
private void initComponents() {
jPanel1 = new javax.swing.JPanel(); //This component will not be managed by spring.
//...
}
You could use the following class provided here, to make it work.
#Component
public class BeanProvider {
private static ApplicationContext applicationContext;
// Autowires the specified object in the spring context
public static void autowire(Object object) {
applicationContext.getAutowireCapableBeanFactory().autowireBean(object);
}
#Autowired
private void setApplicationContext(ApplicationContext applicationContext) {
BeanProvider.applicationContext = applicationContext;
}
}
The top level SwingApp class:
#SpringBootApplication
public class SwingApp implements CommandLineRunner {
public static void main(String[] args) {
new SpringApplicationBuilder(SwingApp.class)
.headless(false).bannerMode(Banner.Mode.OFF).run(args);
}
#Override
public void run(String... args) throws Exception {
SwingUtilities.invokeLater(() -> {
MainFrame frame = new MainFrame();
frame.setVisible(true);
});
}
}
The MainFrame class:
public class MainFrame extends javax.swing.JFrame {
public MainFrame() {
initComponents();
}
private void initComponents() {
//Gui Builder generated code. Bean not managed by spring.
//Thus, autowired inside CustomPanel won't work if you rely on ComponentScan.
jPanel1 = new CustomJPanel();
//...
}
private CustomJPanel jPanel1;
}
The panel class where you want to autowire things:
//#Component //not needed since it wont work with gui generated code.
public class CustomJPanel extends javax.swing.JPanel{
#Autowired
private SomeRepository someRepository
public CustomJPanel(){
BeanProvider.autowire(this); //use someRepository somewhere after this line.
}
}
I have the same problem in a JavaFx project. Service and Component annotated classes were null in UI controllers even if it was shown in context that it was created. Below code worked for me
#Component
public class FxmlLoaderWithContext {
private final ApplicationContext context;
#Autowired
public FxmlLoaderWithContext(ApplicationContext context) {
this.context = context;
FXMLLoader fxmlloader = new FXMLLoader();
fxmlloader.setControllerFactory(context::getBean); //this row ensure services and components to be autowired
}
}
I think it returns null because you using command new to create object, such as new InputNameForm(). When creating object like that, the object isn't managed by Spring. That's why autowired not working.
The solution is registering your class as a bean.
You can use a class like in here.
#Component
public class BeanProvider {
private static ApplicationContext applicationContext;
public static void autowire(Object object) {
applicationContext.getAutowireCapableBeanFactory().autowireBean(object);
}
#Autowired
private void setApplicationContext(ApplicationContext applicationContext) {
BeanProvider.applicationContext = applicationContext;
}
}
And then, in your class InputNameForm constructor, call this:
class InputNameForm() {
BeanProvider.autowire(this);
...
}
And that's it. Spring will take care the rest.
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 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);
So I'm trying to write a standalone application using Spring and Mybatis. I used the same DAO's and stuff for a web application, and everything works fine. I want to be able to reuse as much of that code as possible to automate a process. I need to autowire a DAO and use it from a main() method. Right now, I have it modeled somewhat off of this question: Autowiring a Spring 3.2 standalone application fails so I have something like
public class Main{
#Autowired
DAO dao;
public Main(){
final ApplicationContext context = new FileSystemXmlApplicationContext("src/beans.xml");
AutowireCapableBeanFactory acbFactory = context.getAutowireCapableBeanFactory();
acbFactory.autowireBean(this);
System.out.println(dao);
}
public static void main(String[] args) throws Exception {
Main m = new main();
}
The output is null. My DAO file is an interface and the implemented interface has something like
#Repository
#Component
public class DAOImpl implements DAO{
#Autowired
mapper m;
//some methods
}
How do I get it to autowire properly?
EDIT: As suggested, I tried doing this:
public class Main{
#Autowired
DAO dao;
public Main(){
}
public static void main(String[] args) throws Exception {
Main m = new main();
final ApplicationContext context = new FileSystemXmlApplicationContext("src/beans.xml");
AutowireCapableBeanFactory acbFactory = context.getAutowireCapableBeanFactory();
acbFactory.autowireBean(m);
System.out.println(m.dao);
}
It still prints out null