I have some web app with simple task:
public class CustomTask {
private final Logger logger = LoggerFactory.getLogger(getClass());
#Inject
private CustomDao customDao;
#Override
#Transactional(propagation = Propagation.REQUIRED, timeout = 600)
public int run() {
customDao.doSomething();
}
}
now it work with no problem. But now I want to add implementation of BeanFactoryPostProcessor (implements BeanFactoryPostProcessor)to this task and override this method:
#Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
logger.info(beanFactory.getClass() + "xxxxxxxxxx");
logger.info("The factory contains the followig beans:");
String[] beanNames = beanFactory.getBeanDefinitionNames();
for (int i = 0; i < beanNames.length; ++i)
logger.info(beanNames[i]);
}
but now then I want to do something with customDao it throw NullPointException and I dont know why because in logger I see that this bean is registred. Can you explain me why this exception occurs and how should I fix it ?
This will not work because #Inject (just like #Autowired) is detected by AutowiredAnnotationBeanPostProcessor which is a BeanPostProcessor. BeanFactoryPostProcessors are instantiated BEFORE any other bean in the application context. So, when your post processor is created, the infrastructure that detects #Inject annotation isn't even created and cannot act on your bean factory post processor.
See the api docs for Autowired annotation where there is a note about the restriction for BeanFactoryPostProcessors.
You could make your task to implement BeanFactoryAware and inject the bean yourself:
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
this.customDao = beanFactory.getBean(CustomDao.class);
}
Related
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;
}
I am trying to do an image upload API. I have a ImageUpload task as follows,
#Component
#Configurable(preConstruction = true)
#Scope(BeanDefinition.SCOPE_PROTOTYPE)
public class ImageUploadTask implements Callable<JSONObject> {
#Autowired
private ImageUploadService imageUploadService;
#Override
public JSONObject call() throws Exception {
....
//Upload image via `imageUploadService`
imageUploadService.getService().path('...').post('...'); // Getting null pointer here for imageUploadService which is a WebTarget
}
}
The ImageUploadService looks like the below,
#Component
public class ImageUploadService {
#Inject
#EndPoint(name="imageservice") //Custom annotation, battle tested and works well for all other services
private WebTarget imageservice;
public WebTarget getService() {
return imageservice;
}
}
Here is the spring boot application class,
#ComponentScan
#EnableSpringConfigured
#EnableLoadTimeWeaving(aspectjWeaving=EnableLoadTimeWeaving.AspectJWeaving.ENABLED)
#EnableAutoConfiguration
public class ImageApplication extends SpringBootServletInitializer {
#Bean
public InstrumentationLoadTimeWeaver loadTimeWeaver() throws Throwable {
InstrumentationLoadTimeWeaver loadTimeWeaver = new InstrumentationLoadTimeWeaver();
return loadTimeWeaver;
}
#Override
public void onStartup(ServletContext servletContext) throws ServletException {
super.onStartup(servletContext);
servletContext.addListener(new RequestContextListener());
}
public static void main(String[] args) throws IOException {
SpringApplication.run(ImageApplication.class);
}
}
Additional information :
Spring version of dependencies are at 4.2.5.RELEASE
pom.xml has dependencies added for spring-aspects and
spring-instrument
I am getting a NullPointerException in ImageUploadTask. My suspicion is that #Autowired doesn't work as expected.
Why wouldn't work and how do I fix this?
Is it mandatory to use #Autowired only when I use #Conigurable, why not use #Inject? (though I tried it and getting same NPE)
By default the autowiring for the #Configurable is off i.e. Autowire.NO beacuse of which the imageUploadService is null
Thus update the code to explicity enable it either as BY_NAME or BY_TYPE as below.
#Component
#Configurable(preConstruction = true, autowire = Autowire.BY_NAME)
#Scope(BeanDefinition.SCOPE_PROTOTYPE)
public class ImageUploadTask implements Callable<JSONObject> { .... }
Rest of the configuration viz. enabling load time weaving seems fine.
Also regarding #Inject annotation have a look here which pretty much explains the difference (or similarity perhaps)
We can set the request attributes using Model or ModelAndView object in Spring.
We can use #SessionAttributes to keep attributes in session scope.
Then how can I put an attribute in application scope in Spring, does spring has provided any annotation for that?
Basically all that is needed to configure an application scope is to use the ServletContext, and you can do it in Spring as follows:
public class MyBean implements ServletContextAware {
private ServletContext servletContext;
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}
}
javax.servlet.ServletContext could be even injected to your bean implementation as follows:
#Component
public class MyBean {
#Autowired
private ServletContext servletContext;
public void myMethod1() {
servletContext.setAttribute("attr_key","attr_value");
}
public void myMethod2() {
Object value = servletContext.getAttribute("attr_key");
...
}
}
When you mention about storing your model at application scope then I would conclude you wish to store it at the ServletContext level.
For doing that you need to make your controller implements ServletContextAware interface.
import org.springframework.web.context.ServletContextAware;
// ...
public class MyController implements ServletContextAware {
private ServletContext context;
public void setServletContext(ServletContext servletContext) {
this.context = servletContext;
}
After getting access to ServletContext you can add it as a attribute
servletContext.setAttribute("modelKey", modelObject);
Kindly let me know if this is what you are looking for.
In the spring you can get application scope by using #Autowired annotation
#Autowired
private ServletContext servletContext;
Then you can access you element by using .getAttribute Method
Object someObj = servletContext.getAttribute("object",someObj);
if(someObj==null)
someObj = new Object(); //This will create new Object if it doesn't exists.
servletContext.setAttribute("object",someObj);
I have a controller (for example. MyManager) where I invoke method (for example myMethod() ) of component class (bean), for example MyComponent. I have I servlet where I want to invoke myMethod() . In servlet I have annotated MyManager by #Autowired annotation , despite this I got NullPointerException. I saw this kind of topic but it is not useful for me. For imagination I write little code :
public class myClass extends HttpServlet {
#Autowired
private MyComponent component;
public void init(ServletConfig config) throws ServletException{
super.init(config);
SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
}
protected void doGet(HttpServletRequest req,HttpServletResponse res) throws ... {
List<MyObject> objects =component.myMethod(); // Here is the problem, component is null
}
}
}
I make Spring configuration file "context.xml" and I got bean (component) object, but now I have problem with injected EntityManager in bean object. Now it is null , can anyone help me to solve this problem ? Also update init() method.
public void init(ServletConfig config) throws ServletException{
ApplicationContext con = new ClassPathXmlApplicationContext("context.xml");
component = (MyComponent) con.getBean("myBean");
}
You cannot autowire dependencies like that because Servlets are not Spring Beans. You need to do something like the following:
#Override
public void init() throws ServletException {
super.init();
ApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(getServletContext());
component= applicationContext.getBean(MyComponent.class);
}
Also drop the #Autowired annotation from component
I want to read text data fixtures (CSV files) at the start on my application and put it in my database.
For that, I have created a PopulationService with an initialization method (#PostConstruct annotation).
I also want them to be executed in a single transaction, and hence I added #Transactional on the same method.
However, the #Transactional seems to be ignored :
The transaction is started / stopped at my low level DAO methods.
Do I need to manage the transaction manually then ?
Quote from legacy (closed) Spring forum:
In the #PostConstruct (as with the afterPropertiesSet from the InitializingBean interface) there is no way to ensure that all the post processing is already done, so (indeed) there can be no Transactions. The only way to ensure that that is working is by using a TransactionTemplate.
So if you would like something in your #PostConstruct to be executed within transaction you have to do something like this:
#Service("something")
public class Something {
#Autowired
#Qualifier("transactionManager")
protected PlatformTransactionManager txManager;
#PostConstruct
private void init(){
TransactionTemplate tmpl = new TransactionTemplate(txManager);
tmpl.execute(new TransactionCallbackWithoutResult() {
#Override
protected void doInTransactionWithoutResult(TransactionStatus status) {
//PUT YOUR CALL TO SERVICE HERE
}
});
}
}
I think #PostConstruct only ensures the preprocessing/injection of your current class is finished. It does not mean that the initialization of the whole application context is finished.
However you can use the spring event system to receive an event when the initialization of the application context is finished:
public class MyApplicationListener implements ApplicationListener<ContextRefreshedEvent> {
public void onApplicationEvent(ContextRefreshedEvent event) {
// do startup code ..
}
}
See the documentation section Standard and Custom Events for more details.
As an update, from Spring 4.2 the #EventListener annotation allows a cleaner implementation:
#Service
public class InitService {
#Autowired
MyDAO myDAO;
#EventListener(ContextRefreshedEvent.class)
public void onApplicationEvent(ContextRefreshedEvent event) {
event.getApplicationContext().getBean(InitService.class).initialize();
}
#Transactional
public void initialize() {
// use the DAO
}
}
Inject self and call through it the #Transactional method
public class AccountService {
#Autowired
private AccountService self;
#Transactional
public void resetAllAccounts(){
//...
}
#PostConstruct
private void init(){
self.resetAllAccounts();
}
}
For older Spring versions which do not support self-injection, inject BeanFactory and get self as beanFactory.getBean(AccountService.class)
EDIT
It looks like that since this solution has been posted 1.5 years ago developers are still under impression that if a method,
annotated with #Transactional, is called from a #PostContruct-annotated method invoked upon the Bean initialization, it won't be actually executed inside of Spring Transaction, and awkward (obsolete?) solutions get discussed and accepted instead of this very simple and straightforward one and the latter even gets downvoted.
The Doubting Thomases :) are welcome to check out an example Spring Boot application at GitHub which implements the described above solution.
What actually causes, IMHO, the confusion: the call to #Transactional method should be done through a proxied version of a Bean where such method is defined.
When a #Transactional method is called from another Bean, that another Bean usually injects this one and invokes its proxied (e.g. through #Autowired) version of it, and everything is fine.
When a #Transactional method is called from the same Bean directly, through usual Java call, the Spring AOP/Proxy machinery is not involved and the method is not executed inside of Transaction.
When, as in the suggested solution, a #Transactional method is called from the same Bean through self-injected proxy (self field), the situation is basically equivalent to a case 1.
#Platon Serbin's answer didn't work for me. So I kept searching and found the following answer that saved my life. :D
The answer is here No Session Hibernate in #PostConstruct, which I took the liberty to transcribe:
#Service("myService")
#Transactional(readOnly = true)
public class MyServiceImpl implements MyService {
#Autowired
private MyDao myDao;
private CacheList cacheList;
#Autowired
public void MyServiceImpl(PlatformTransactionManager transactionManager) {
this.cacheList = (CacheList) new TransactionTemplate(transactionManager).execute(new TransactionCallback(){
#Override
public Object doInTransaction(TransactionStatus transactionStatus) {
CacheList cacheList = new CacheList();
cacheList.reloadCache(MyServiceImpl.this.myDao.getAllFromServer());
return cacheList;
}
});
}
The transaction part of spring might not be initialized completely at #PostConstruct.
Use a listener to the ContextRefreshedEvent event to ensure, that transactions are available:
#Component
public class YourService
implements ApplicationListener<ContextRefreshedEvent> // <= ensure correct timing!
{
private final YourRepo repo;
public YourService (YourRepo repo) {this.repo = repo;}
#Transactional // <= ensure transaction!
#Override
public void onApplicationEvent(ContextRefreshedEvent event) {
repo.doSomethingWithinTransaction();
}
}
Using transactionOperations.execute() in #PostConstruct or in #NoTransaction method both works
#Service
public class ConfigurationService implements ApplicationContextAware {
private static final Logger LOG = LoggerFactory.getLogger(ConfigurationService.class);
private ConfigDAO dao;
private TransactionOperations transactionOperations;
#Autowired
public void setTransactionOperations(TransactionOperations transactionOperations) {
this.transactionOperations = transactionOperations;
}
#Autowired
public void setConfigurationDAO(ConfigDAO dao) {
this.dao = dao;
}
#PostConstruct
public void postConstruct() {
try { transactionOperations.execute(new TransactionCallbackWithoutResult() {
#Override
protected void doInTransactionWithoutResult(final TransactionStatus status) {
ResultSet<Config> configs = dao.queryAll();
}
});
}
catch (Exception ex)
{
LOG.trace(ex.getMessage(), ex);
}
}
#NoTransaction
public void saveConfiguration(final Configuration configuration, final boolean applicationSpecific) {
String name = configuration.getName();
Configuration original = transactionOperations.execute((TransactionCallback<Configuration>) status ->
getConfiguration(configuration.getName(), applicationSpecific, null));
}
#Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
}
}