How can we get access to ApplicationContext from a CommandLineRunner class. Is there a better newer way than using ApplicationContextAware
Autowiring would work, either as a field
#Autowired
private ApplicationContext context;
or a method
#Autowired
public void context(ApplicationContext context) { this.context = context; }
Same as ApplicationContextAware really.
It's a smell in any case - maybe if you think about your use case you will find a way to do it without the context?
#Bean
#Autowired
public CommandLineRunner listAllBeans(ApplicationContext applicationContext) {
return new CommandLineRunner() {
#Override
public void run(String... args) throws Exception {
String[] allBeanNames = applicationContext.getBeanDefinitionNames();
System.out.println("doing listAllBeans");
for(String beanName : allBeanNames) {
System.out.println(beanName);
}
}
};
}
Related
my colde below
/* this bean is the bean that alwyas returned as null*/
#Component
public class ContextHolder implements ApplicationContextAware, ServletContextAware {
private static ApplicationContext springContext;
private static ServletContext servletContext;
#Override
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}
#Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.springContext = applicationContext;
}
public static ApplicationContext getSpringContext() {
return springContext;
}
public static ServletContext getServletContext() {
return servletContext;
}
}
#Component
#PropertySource("classpath:appProps/globals-${spring.profiles.active}.properties")
public class PropertyManager extends PropertySourcesPlaceholderConfigurer {
#Autowired
ContextHolder contextHolder; // this binding alwasy return null. I don't know the why
public String get(String key) {
// NullpointerException occurs, because contextHolder is null
// But ContextHodler.getSpringContext() static access works, but I want to know
// why Autowired does not work
return contextHolder.getSpringContext().getEnvironment().getProperty(key);
}
}
I want to know why Autowired does not work.
I have search the answer in google. but there no documents about this.
I guess PropertySourcesPlaceholderConfigurer is type of BeanFactoryPostProcessor, So when initialize the PropertySourcesPlaceHolderConfiguer there are no bean of ContextHolder instance in memory, thus contextHolder is null??
I'm using Bean Validation. I have a custom validator #MyValidator that needs to look up a value with an injected Spring managed DAO object. How can I get access to this? Spring isn't injecting the DAO into my "MyValidator" object.
#Component
public class CodeListValidator implements ConstraintValidator<CodeList, String> {
#Autowired
private ICodeListCommonService codeListCommonService;
private CodeListEnum codeListID;
#Override
public void initialize(CodeList constraintAnnotation) {
this.codeListID = constraintAnnotation.value();
}
#Override
public boolean isValid(String value, ConstraintValidatorContext context) {
return codeListCommonService.doesCodeEntityExistForCodeList(codeListID.getDbCodeListId(), value, ProviderConstants.CODE_LIST_STATUS_ACTIVE);
}
}
The "codeListCommonService" is null. This is because Spring isn't creating the class - but how can I get this to work with Spring AoP?
The use of this validator looks like this:
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
MyObject validateMe = new MyObject();
Set<ConstraintViolation<MyObject>> constraintViolations = validator.validate(validateMe);
For MyObject:
public class MyObject {
#Size(max = 1)
#CodeList(CodeListEnum.CARTYPE)
public String carType;
}
So when the validator runs, it processes the annotations... I just need to get a service injected into the CodeListValidator I made to it can do a DB lookup to verify the value against the DB list of "valid car type values".
EDIT: The solution:
Played around with the idea of making a Spring aware factory- too much integration with existing code.
The solution that seems the best (and it works here) is to make a Spring service that stores the ApplicationContext in a static method so "non-Spring managed" beans can get to them.
So a new service:
#Service
public class SpringApplicationContextService implements ISpringApplicationContextService, ApplicationContextAware {
private static ApplicationContext applicationContext;
#Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
}
And then any validator or non-Spring bean can get at the Spring beans via:
public class CodeListValidator implements ConstraintValidator<CodeList, String> {
#Autowired
private ICodeListCommonService codeListCommonService;
private CodeListEnum codeListID;
#Override
public void initialize(CodeList constraintAnnotation) {
this.codeListID = constraintAnnotation.value();
}
#Override
public boolean isValid(String value, ConstraintValidatorContext context) {
ICodeListCommonService codeListCommonService = SpringApplicationContextService.getApplicationContext().getBean(ICodeListCommonService.class);
return codeListCommonService.doesCodeEntityExistForCodeList(codeListID.getDbCodeListId(), value, ProviderConstants.CODE_LIST_STATUS_ACTIVE);
}
}
And, of course, the reason for all of this (which is used dozens of times in this app):
#CodeList(CodeListEnum.EMAIL_OPT_OUT_FLAG)
public String emailOptOutFlag;
#CodeList(CodeListEnum.CLEARING_HOUSE)
public String clearingHouse;
The minimum setup for #Autowired to work properly in ConstraintValidator implementation is to have this bean in a Spring #Configuration:
#Bean
public Validator defaultValidator() {
return new LocalValidatorFactoryBean();
}
This allows any beans, including ApplicationContext, to be injected directly into a ConstraintValidator:
#Constraint(validatedBy = DemoValidator.class)
public #interface DemoAnnotation {
// ...
Class<?> beanClass();
}
public class DemoValidator implements ConstraintValidator<DemoAnnotation, String> {
private final ApplicationContext applicationContext;
private Object bean;
#Autowired
public DemoValidator(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}
#Override
public void initialize(DemoAnnotation constraint) {
Class<?> beanClass = constraint.beanClass();
bean = applicationContext.getBean(beanClass);
}
#Override
public boolean isValid(String obj, ConstraintValidatorContext context) {
return !obj.isEmpty();
}
}
Demo
For a really flexible validation solution I would recommend Jakub Jirutka's Bean Validator utilizing Spring Expression Language (SpEL) which allows things like:
public class Sample {
#SpELAssert("#myService.calculate(#this) > 42")
private int value;
}
How do i #autowire bean class TransactionManagerImpl which is having 1(String) argument constructor without using new in spring-boot application?
Even after searching through many post i couldn't get any clue to autowire without using new
I need to autowire TransactionManager in three different classes and the parameters are different in all three classes.
This looks like very basic scenario.
#Service
public class TransactionManagerImpl implements TransactionManager {
private final Logger logger = LoggerFactory.getLogger(this.getClass());
String txnLogFile;
#ConstructorProperties({"txnLogFile"})
public TransactionManagerImpl(String txnLogFile) {
this.txnLogFile= txnLogFile;
}
}
is there any specific requirement where you want to use #Service annotation?
if not then you can use #Bean to create a bean for TransactionManagerImpl like below.
#Configuration
public class Config {
#Value("${txnLogFile}")
private String txnLogFile;
#Bean
public TransactionManager transactionManager() {
return new TransactionManagerImpl(txnLogFile);
}
}
and remove #Service annotation from TransactionManagerImpl.
Putting aside other complications, it can be done like this
public TransactionManagerImpl(#Value("${txnLogFile}") String txnLogFile) {
this.txnLogFile= txnLogFile;
}
Finally, i did it as below, now sure if this is the best way to do. I did not want to have three implementation just because of one variable.
application.yaml
app:
type-a:
txn-log-file: data/type-a-txn-info.csv
type-b:
txn-log-file: data/type-b-txn-info.csv
default:
txn-log-file: data/default/txn-info.csv
MainApplication.java
#SpringBootApplication
public class MainApplication {
public static void main(String[] args) {
new SpringApplicationBuilder(MainApplication.class).web(WebApplicationType.NONE).run(args);
}
#Bean
public TransactionManager transactionManager(#Value("${app.default.txn-log-file}") String txnLogFile) {
return new TransactionManagerImpl(txnLogFile);
}
#Bean
public CsvService csvService(String txnLogFile) {
return new CsvServiceImpl(txnLogFile);
}
}
TypeOneRoute.java
#Configuration
public class TypeOneRoute extends RouteBuilder {
#Value("${app.type-a.txn-log-file}")
private String txnLogFile;
#Autowired
private ApplicationContext applicationContext;
private TransactionManager transactionManager;
#Override
public void configure() throws Exception {
transactionManager = applicationContext.getBean(TransactionManager.class, txnLogFile);
transactionManager.someOperation();
}
}
TypeTwoRoute.java
#Configuration
public class TypeTwoRoute extends RouteBuilder {
#Value("${app.type-b.txn-log-file}")
private String txnLogFile;
#Autowired
private ApplicationContext applicationContext;
private TransactionManager transactionManager;
#Override
public void configure() throws Exception {
transactionManager = applicationContext.getBean(TransactionManager.class, txnLogFile);
transactionManager.create();
}
}
TransactionManager.java
#Service
#Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)
public interface TransactionManager {
public ZonedDateTime create() throws IOException, ParseException;
}
TransactionManagerImpl.java
public class TransactionManagerImpl implements TransactionManager {
#Autowired
private ApplicationContext applicationContext;
private String txnLogFile;
public TransactionManagerImpl(String txnLogFile) {
this.txnLogFile = txnLogFile;
}
private CsvService csvService;
#PostConstruct
public void init() {
csvService = applicationContext.getBean(CsvService.class, txnLogFile);
}
public ZonedDateTime create() throws IOException, ParseException {
try {
csvService.createTxnInfoFile();
return csvService.getLastSuccessfulTxnTimestamp();
} catch (IOException e) {
throw new IOException("Exception occured in getTxnStartDate()", e);
}
}
}
Initially TransactionManager Bean will be registered with the app.default.txn-info.csv and when i actually get it from ApplicationContext i am replacing the value with the parameter passed to get the bean from ApplicationContext
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 have defined a service in Spring
#Service("StockageService")
public class StockageServiceImpl implements StockageService{
}
with
public interface StockageService extends Serializable {
}
And I need in a servlet to invoke this service
So I wrote
public class SpringApplicationContextListener implements ServletContextListener {
#Override
public void contextInitialized(ServletContextEvent sce) {
ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
sce.getServletContext().setAttribute("applicationContext", ac);
}
public void contextDestroyed(ServletContextEvent sce) {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}
}
And
public class handler extends HttpServlet {
private String message;
private StockageService stockageService;
#Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
ApplicationContext ac = (ApplicationContext) config.getServletContext().getAttribute("applicationContext");
this.stockageService = (StockageService)ac.getBean("StockageService");
}
The problem is that I get a NPE at the last mentionned line
(StockageService)ac.getBean("StockageService");
Where could I have made a mistake ?
First, thanks ankur-singhal for having taken the time to answer my question
I understand the reasonnement of your answer but it does not work when I invoke
ApplicationContextUtils. getApplicationContext().getBean("StockageService");
So I used a trick which works but I do not understand very well
I override the init in my servlet as it follows
#Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this,
config.getServletContext());
}
and I have to put a
#Autowired
private StockageService stockageService;
in the servlet and it works
It seems that ApplicationContext itself is comming as null.
Look at below code and try make use of this.
ApplicationContextUtils.java
We will create the following utility class, it implements ApplicationContextAware and provides the setApplicationContext which will be invoked by spring container and the applicationContext will be passed by it. We store it in a static variable and expose it through a get method so that it can be accessed all through the application.
You can set the same while creating ApplicationContext
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
public class ApplicationContextUtils implements ApplicationContextAware {
private static ApplicationContext ctx;
#Override
public void setApplicationContext(ApplicationContext appContext)
throws BeansException {
ctx = appContext;
}
public static ApplicationContext getApplicationContext() {
return ctx;
}
}