I am trying to make use of Spring Boot AutoConfigured #EnableScheduling to create a cron job. Job triggers perfectly fine if the fixedRateString is hardcoded. However it does not succeed if I try to make use of SpEL to supply the value.
//Bean Instantiation in JavaConfig
#Bean
public AlertbotJob2 getAlertJob2() {
AlertbotJob2 alertbotJob2 = new AlertbotJob2("alertId", "alertName", "alertSubject", "6000", true);
return alertbotJob2;
}
Bean Definition
public class AlertbotJob2 {
String alertId;
String alertName;
String alertSubject;
public String cronPattern;
boolean isActive;
public AlertbotJob2() {
}
public AlertbotJob2(String alertId, String alertName, String alertSubject, String cronPattern, boolean isActive) {
super();
this.alertId = alertId;
this.alertName = alertName;
this.alertSubject = alertSubject;
this.cronPattern = cronPattern;
this.isActive = isActive;
}
#Scheduled(initialDelay = 60000, fixedRateString = "#{this.cronPattern}")
public void doTheJob() {
System.out.println("DoSomething");
}
}
Exception is :: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelEvaluationException: EL1008E: Property or field 'this' cannot be found on object of type 'org.springframework.beans.factory.config.BeanExpressionContext' - maybe not public?
I am just trying to set the trigger values dynamically. Please help.
You can't use this there.
You have to do it by bean name #someBean.cronPattern.
I don't think you can use SpEL like this.
Maybe the better approach is to define your cron pattern in some property like:
myapp.scheduler.cronPattern=...
And then use the following syntax:
#Scheduled(cron = "${myapp.scheduler.cronPattern}")
public void doTheJob() {
...
}
Solution 1: use the hardcoded pattern if its already known
#Scheduled(cron = "0 0/5 * * * MON-FRI")
Solution 2: If the pattern is available in some property
#Scheduled(cron = "${myapp.scheduler.cronPattern}")
Solution 3 : This approach does not use annotation. Instead the Beans are just implemented as runnables And then override the SchedulingConfigurer.configureTasks() to dynamically set the schedules using taskRegistrar.addCronTask(urRunnableJob, urCronPatternFromDB); . Cron pattern is stored in database table, initialize it as properties as below.
class AppConfig {
#Autowired
ConfigurableEnvironment environment;
private void initPropertiesMap() {
environment.getPropertySources()
.addLast(new MapPropertySource("myAppProperties", myAppProperties.getProperties())); // Prior DAO call required to read the configs from database
}
#PostConstruct
public void postConstruct() {
initPropertiesMap();
}
}
you can try this:
e.g #Value("#{T(com.someName.ClassName).cronPattern}")
I reference this Accessing static variable in spring annotations using spel
Related
I am trying to inject some property values into variables by means of Spring #Value annotation but I get null values. I tried different configurations and triks but it doesn't work. Think is that before today everythink was working properly. I do not know what I changed in order to get things broken.
Here is my java class:
#Component
#ConditionalOnProperty(prefix = "studioghibli", name = "get")
public class StudioGhibliRestService {
#Value("${studioghibli.basepath}")
private static String BASE_PATH;
#Value("${studioghibli.path}")
private static String PATH;
#Value("${studioghibli.protocol:http}")
private static String PROTOCOL;
#Value("${studioghibli.host}")
private static String HOST;
private static String BASE_URI = PROTOCOL.concat("://").concat(HOST).concat(BASE_PATH).concat(PATH);
#Autowired
StudioGhibliRestConnector connector;
public List<StudioGhibliFilmDTO> findAllFilms() throws SipadContenziosoInternalException {
var response = connector.doGet(BASE_URI, null, null);
if (!response.getStatusCode().is2xxSuccessful() || !response.hasBody()) {
throw new SipadContenziosoInternalException(Errore.INTERNAL_REST_ERROR, "FindAll(), microservizio ".concat(BASE_URI), null);
}
return (List<StudioGhibliFilmDTO>) response.getBody();
}
}
As you can see, the class is annotated with #Component, that because I will need to use it as #Service layer in order to make a rest call in my business logic.
The class is also annotaded with conditional on property...
Here is a screenshot of the debug window at startup:
Since the PROTOCOL value is null, i get a null pointer exception immediately at start up.
Here is part of the application-dev.properties file:
studioghibli.get
studioghibli.protocol=https
studioghibli.host=ghibliapi.herokuapp.com
studioghibli.basepath=/
studioghibli.path=/films
First of all, #Value annotation does not work with static fields.
Secondly, fields with #Value annotation is processed when the instance of the class (a bean) is created by Spring, but static fields exist for a class (for any instance), so when the compiler is trying to define your static BASE_URI field other fields are not defined yet, so you get the NPE on startup.
So you might need a refactoring, try to inject values with the constructor like this:
#Component
#ConditionalOnProperty(prefix = "studioghibli", name = "get")
public class StudioGhibliRestService {
private final StudioGhibliRestConnector connector;
private final String baseUri;
public StudioGhibliRestService(StudioGhibliRestConnector connector,
#Value("${studioghibli.basepath}") String basePath,
#Value("${studioghibli.path}") String path,
#Value("${studioghibli.protocol:http}") String protocol,
#Value("${studioghibli.host}") String host) {
this.connector = connector;
this.baseUri = protocol.concat("://").concat(host).concat(basePath).concat(path);
}
// other code
}
Thanks, It works for me, I have to add some codes to my project. Then I check the spring core document in "#Value" section. Besides
When configuring a PropertySourcesPlaceholderConfigurer using
JavaConfig, the #Bean method must be static.
#Bean
public static PropertySourcesPlaceholderConfigurer propertyPlaceholderConfigurer(){
return new PropertySourcesPlaceholderConfigurer();
}
I have a use case where it would be extraordinarily nice to dynamically instantiate beans (using some kind of factory approach) based on annotation-arguments at the injection point. Specifically, I need to be able to specify a type-argument to the bean-creating factory.
A pretty relevant example would be a JSON deserializer that needs the type which it needs to deserialize to.
I envision either:
#Inject
#DeserializeQualifier(Car.class)
private Deserializer<Car> _carDeserializer;
#Inject
#DeserializeQualifier(Bus.class)
private Deserializer<Bus> _busDeserializer;
.. or simply, if it was possible to sniff the type from the generic type argument:
#Inject
private Deserializer<Car> _carDeserializer;
#Inject
private Deserializer<Bus> _busDeserializer;
The big point here is that I would not know beforehand which types was needed in the project, as this would be a generic tool that many projects would include. So you would annotate your #Configuration class with #EnableDeserializer and could then inject any type deserializer (The factory that makes these deserializers can handle any type, but to be able create one, it would need to know the desired type of the deserialized object - plain generics would not cut it, since Java ain't using reified generics).
So, I'd need to be able to inject into the spring context, or using any other Spring magic tricks, some kind of DeserializerFactory that takes the type argument.
Basically, I need to have Spring invoke the following method based based on either, as in the first example, the qualifier argument (or the entire DeserializeQualifier-instance for that matter), or as in the second example, the generic type argument:
DeserializerFactory {
<T> Deserializer<T> createDeserializer(Class<T> type) { ... }
}
You could create a BeanFactoryPostProcessor to set attributes annotated with a custom annotation. I've set up a small Spring Boot project to play around:
// Custom annotation
#Target(ElementType.FIELD)
#Retention(RetentionPolicy.RUNTIME)
public #interface InjectSomeClassHere {
Class value();
}
// Demo bean
#Component
public class SomeBean {
#InjectSomeClassHere(String.class)
private Class someValue;
public Class getInjectedClass() {
return someValue;
}
}
// The BeanFactoryPostProcessor
#Component
public class SomeBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
#Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
Arrays
.stream(beanFactory.getBeanDefinitionNames())
.filter(beanName -> hasAnnotatedField(beanFactory, beanName))
.forEach(beanName -> {
Object bean = beanFactory.getBean(beanName);
Stream.of(bean.getClass().getDeclaredFields()).forEach(field -> setFieldValue(bean, field));
});
}
private boolean hasAnnotatedField(ConfigurableListableBeanFactory beanFactory, String beanName) {
try {
String className = beanFactory.getBeanDefinition(beanName).getBeanClassName();
if (className == null) {
return false;
}
return Arrays.stream(Class.forName(className).getDeclaredFields())
.anyMatch(field -> field.isAnnotationPresent(InjectSomeClassHere.class));
} catch (ClassNotFoundException e) {
// Error handling here
return false;
}
}
private void setFieldValue(Object filteredBean, Field field) {
try {
// Note: field.isAccessible() is deprecated
if (!field.isAccessible()) {
field.setAccessible(true);
}
// Retrieve the value from the annotation and set the field
// In your case, you could call `createDeserializer(fieldValue);` and set the field using the return value.
// Note that you should change the type of `SomeBean#someValue` accordingly.
Class fieldValue = field.getAnnotation(InjectSomeClassHere.class).value();
field.set(filteredBean, fieldValue);
} catch (IllegalAccessException e) {
// Error handling here
e.printStackTrace();
}
}
}
// A small test to verify the outcome of the BeanFactoryPostProcessor
#RunWith(SpringRunner.class)
#SpringBootTest
public class SomeBeanTests {
#Autowired
private SomeBean someBean;
#Test
public void getInjectedClass_shouldHaveStringClassInjected() {
Assert.assertEquals(String.class, someBean.getInjectedClass());
}
}
Please note that this is a very naive implementation and requires further fine tuning. For instance, it scans all attributes in all spring components for the presence of an annotation.
Good luck with your project!
I would like to make the execution of an event handler dependent on whether or not a property is set to true in a properties file.
#EventListener(ContextRefreshedEvent.class, condition = "${service.enabled}")
public void onStartup() { }
However, this does not seem to work. I am getting the following error on startup:
org.springframework.expression.spel.SpelParseException: EL1043E:(pos 1): Unexpected token. Expected 'identifier' but was 'lcurly({)'
Is it possible to use a property from a properties file as a condition here?
The issue is condition argument is expecting a SPEL.
This works try it out.
In your bean where you have this #EventListener, add these lines
public boolean isServiceEnabled() {
return serviceEnabled;
}
#Value("${service.enabled}")
public boolean serviceEnabled;
change your declaration of evnt listener like this
#EventListener(classes = ContextRefreshedEvent.class, condition = "#yourbeanname.isServiceEnabled()")
public void onStartup() { }
change yourbeanname with the correct bean name .
I had the same annoying experience (with Spring Boot 2.4.2 on Java11).
In my case I had the boolean property in a #ConfigurationProperties class anyways in the same java file and still struggled a bit. First the #ConfigurationProperties need to be annotated as #Component to actually be a valid Bean and can be used in SpEL.
And I had to use the same long attributeName for the ConfigurationProperties in the Service itself and the EventListener Annotation for the Bean resolution to work fine. I needed some the ConfigurationProperties values also in another place of the Service, that's why they needed to be (Constructor) Autowired as well...
So this worked for me:
#ConfigurationProperties("my.custom.path")
#Component //Important to make this a proper Spring Bean
#Data //Lombok magic for getters/setters etc.
class MyCustomConfigurationProperties {
boolean refreshAfterStartup = true;
}
#Service
#RequiredArgsConstructor //Lombok for the constructor
#EnableConfigurationProperties(MyCustomConfigurationProperties.class)
#EnableScheduling
public class MyCustomService {
private final MyCustomConfigurationProperties myCustomConfigurationProperties;
#EventListener(value = ApplicationReadyEvent.class, condition = "#myCustomConfigurationProperties.refreshAfterStartup")
public void refresh() {
//the actual code I want to execute on startup conditionally
}
}
I have Spring 4.1 Application. I am trying to schedule based on value from property file. I have read this post. But I do not want the following way of EL inside #Scheduled
#Scheduled(fixedDelayString = "${my.fixed.delay.prop}")
public void readLog() {
...
}
Here is my class.
public class MyService {
#Value("${timerInMilliSeconds: 60000}")
private long timerinMilliSeconds;
public myService(){
}
#Scheduled(fixedRate = timerinMilliSeconds)
public void myTimer() {
//do stuff
}
}
I get this error.
The value for annotation attribute Scheduled.fixedRate must be a constant
expression
You can't do that; it's a limitation of the way annotations work - Strings in annotations have to be constants (they are stored in the class and can't be different for each instance).
By the way ${my.fixed.delay.prop} is not "EL", it's a property placeholder.
With this class
#Component
public class Sample {
#Value("${my.name}")
public static String name;
}
If I try Sample.name, it is always 'null'. So I tried this.
public class Sample {
public static String name;
#PostConstruct
public void init(){
name = privateName;
}
#Value("${my.name}")
private String privateName;
public String getPrivateName() {
return privateName;
}
public void setPrivateName(String privateName) {
this.privateName = privateName;
}
}
This code works. Sample.name is set properly. Is this good way or not? If not, is there something more good way? And how to do it?
First of all, public static non-final fields are evil. Spring does not allow injecting to such fields for a reason.
Your workaround is valid, you don't even need getter/setter, private field is enough. On the other hand try this:
#Value("${my.name}")
public void setPrivateName(String privateName) {
Sample.name = privateName;
}
(works with #Autowired/#Resource). But to give you some constructive advice: Create a second class with private field and getter instead of public static field.
Soruce of this info is this: https://www.baeldung.com/spring-inject-static-field
Spring uses dependency injection to populate the specific value when it finds the #Value annotation. However, instead of handing the value to the instance variable, it's handed to the implicit setter instead. This setter then handles the population of our NAME_STATIC value.
#RestController
//or if you want to declare some specific use of the properties file then use
//#Configuration
//#PropertySource({"classpath:application-${youeEnvironment}.properties"})
public class PropertyController {
#Value("${name}")//not necessary
private String name;//not necessary
private static String NAME_STATIC;
#Value("${name}")
public void setNameStatic(String name){
PropertyController.NAME_STATIC = name;
}
}
This is my sample code for load static variable
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
#Component
public class OnelinkConfig {
public static int MODULE_CODE;
public static int DEFAULT_PAGE;
public static int DEFAULT_SIZE;
#Autowired
public void loadOnelinkConfig(#Value("${onelink.config.exception.module.code}") int code,
#Value("${onelink.config.default.page}") int page, #Value("${onelink.config.default.size}") int size) {
MODULE_CODE = code;
DEFAULT_PAGE = page;
DEFAULT_SIZE = size;
}
}
For those who want to use ApplicationContext in the main class of a Spring Boot application, you can just use the return value of SpringApplication.run.
Although workarounds may need to be implemented, one should try to avoid them in most scenarios if possible. Spring is great at handling dependency injection and treats most objects as Singletons. This means that Spring can handle the creation of objects for you, and the injection of these objects at runtime. When combining this with the fact that your Spring managed bean is likely a Singleton, the use of static methods and variables is largely unnecessary. You can simply autowire in an instance of the object you are looking for at the constructor level or variable level and reference the non-static version of the method or variable. This is ideal and behaves similarly to a static reference. Non static variables are basically static because you are only ever using one instance of the object in every part of the code and because of dependency injection you are never handling the instantiation of the object, just like with a static reference! Great! Now I'm sure there are instances where you need the work around (i.e. you aren't using dependency injection or class is not a singleton), but try to not use workarounds if possible. Also this is just my 2 cents. Someone may be able to offer 3. (:
public class InjectableClass{
#Value("${my.value}")
private String myString;
public String nonStaticMethod(){
return myString;
}
}
public class LogicClass{
private InjectableClass injectableClass;
#Autowire
public LogicClass(InjectableClass injectableClass){
this.injectableClass = injectableClass;
}
public void logicClassMethod(){
System.out.println("Hey! Here is the value I set on myString: " +
injectableClass.nonStaticMethod() + ". That was
basically like using a static method!");
}
}