Is it possible to inject a value to a wicket page using spring?
With #Value it's possible to inject values to a spring bean.
I know the #SpringBean annotation, but this is only for beans.
My workaround is to wrap the value with a spring bean and then inject this with #SpringBean to my wicket page. Is there a better way to do this?
We have solved this problem using getter & setter in our custom child of WebApplication. This child is standard Spring bean and is configured in spring's configuration.
Otherwise you have to create some "config" bean.
You can write a Wicket resource loader to load spring values, and then those values will be resolved like regular wicket messages. If instead you need it within the body of the wicket class to do some business logic, that may be an opportunity to refactor that logic outside of the view layer.
Here's what the resource loader looks like:
public class SpringPropertiesResourceLoader
implements IStringResourceLoader
{
public SpringPropertiesResourceLoader()
{
}
#Override
public String loadStringResource(Class<?> clazz, String key, Locale locale, String style, String variation)
{
return loadStringResource(key);
}
#Override
public String loadStringResource(Component component, String key, Locale locale, String style, String variation)
{
return loadStringResource(key);
}
private String loadStringResource(String key)
{
try
{
ApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(WebPortalApplication.get().getServletContext());
ConfigurableBeanFactory beanFactory = (ConfigurableBeanFactory)applicationContext.getAutowireCapableBeanFactory();
String rv = beanFactory.resolveEmbeddedValue("${" + key + "}");
return rv;
}
catch (IllegalArgumentException iae)
{
// no property with the name - move along
return null;
}
}
}
Then add that to your application in init():
getResourceSettings().getStringResourceLoaders().add(new SpringPropertiesResourceLoader());
Related
I am trying to inject some property values into variables by means of Spring #Value annotation but I get null values. I tried different configurations and triks but it doesn't work. Think is that before today everythink was working properly. I do not know what I changed in order to get things broken.
Here is my java class:
#Component
#ConditionalOnProperty(prefix = "studioghibli", name = "get")
public class StudioGhibliRestService {
#Value("${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();
}
Trying to implement configuration properties validation for immutable beans as described in Spring boot docs:
#Validated
#ConstructorBinding
I'm using Spring boot 2.4.0.
Sample immutable properties class:
#Validated
#ConstructorBinding
#ConfigurationProperties("prefix")
public class Props {
private final String suffix;
public Props(#NotBlank String suffix) {
this.suffix = suffix;
}
public String getSuffix() {
return suffix;
}
#Override
public String toString() {
return "Props [suffix=" + suffix + "]";
}
}
For a test, I did this:
System.setProperty("prefix.suffix", "value");
and I get the correct binding, i.e.:
Props [suffix=value]
However, by making a typo in the property name (added 1 to the property name):
System.setProperty("prefix.suffix1", "value");
I get this:
Props [suffix=null]
I see validation activated in the logs:
HV000001: Hibernate Validator 6.1.6.Final
Form their docs, it is supposed to do constructor parameter validation:
As of Bean Validation 1.1, constraints can not only be applied to JavaBeans and their properties, but also to the parameters and return values of the methods and constructors of any Java type.
Why is #NotBlank (full import: import javax.validation.constraints.NotBlank;) not causing validation exceptions?
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 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 ${my.fixed.delay.prop} is not "EL", it's a property placeholder.
Is there any way for a Spring Boot web application to abort at startup if a required property is not set anywhere (neither in the application.properties file nor the other property sources)? Right now, if the property is included in another property, it seem that Spring Boot simply avoids substitution.
For example, in my application.properties file, I have the line:
quartz.datasource.url=jdbc:hsqldb:${my.home}/database/my-jobstore
Right now, if "my.home" is not set elsewhere, Spring Boot is setting the url literally to "jdbc:hsqldb:${my.home}/database/my-jobstore" (no substitution).
I would like to have the application fail to start if the property my.home were not set anywhere else.
To throw a friendly exceptions just put a default null value in property, check and throw a exception in afterProperty method.
#Component
public static class ConfigurationGuard implements InitializingBean {
#Value("${my.home:#{null}}")
private String myHomeValue;
public void afterPropertiesSet() {
if (this.myHomeValue == null or this.myHomeValue.equals("${my.home}") {
throw new IllegalArgumentException("${my.home} must be configured");
}
}
}
Create a bean with a simple #Value(${my.home}) annotated field. - Then Spring will try to inject that value and will fail and therefore stop when the value is not there.
Just #Value(${my.home}) private String myHomeValue; is enough for normal (not Boot) Spring applications for sure! But I do not know whether Boot has some other configuration to handle missing values: If there is an other failure management than you could check that value in an PostCreation method.
#Component
public static class ConfigurationGuard implements InitializingBean {
#Value(${my.home})
private String myHomeValue;
/**
* ONLY needed if there is some crude default handling for missing values!!!!
*
* So try it first without this method (and without implements InitializingBean)
*/
public void afterPropertiesSet() {
if (this.myHomeValue == null or this.myHomeValue.equals("${my.home}") {
throw new IllegalArgumentException("${my.home} must be configured");
}
}
}
The default behaviour in current versions of Spring Boot (1.5.x, 2.0.x, 2.1.x) is to throw an exception if a placeholder can not be resolved.
There will a be an exception like this one :
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'app.foo.undefined' in value "${app.foo.undefined}"
It works because a bean of type PropertySourcesPlaceholderConfigurer (from spring-context) is automatically registered in Spring Boot, in this class : PropertyPlaceholderAutoConfiguration. And by default, the property ignoreUnresolvablePlaceholders in PropertySourcesPlaceholderConfigurer is set to false, which means an exception must be thrown if a placeholder is unresolved (be it nested or not).
Although they work, I think the approach in the foremost answer is somewhat brittle, as it only works for the predefined name(s), and will silently stop checking the when someone changes quartz.datasource.url in the configs to use a different expansion.
Ideally, I want this value of ignoreUnresolvablePlaceholders to be false to get wholesale expansion checking when parsing my configs such as application.properties or its YAML variants, but it's hard-coded to true for these cases. This unfortunately leaves strings such as ${FOO} in its unexpanded form if FOO cannot be found, making troubleshooting extremely painful. This is especially the case for fields that don't readily appear in the logs such as passwords.
While I couldn't find a way of changing ignoreUnresolvablePlaceholders short of modifying Spring Boot's classes, I did find an alternative of using a custom PropertySource implementation and defining a new syntax such as "${!FOO}" to indicate FOO must exist as an environment variable or die. (The OP didn't mention whether my.home is an environment variable but the code below is for environment variables.)
First, an EnvironmentPostProcessor implementation is required for registering the custom PropertySource. This StrictSystemEnvironmentProcessor.java does this as well as holds the implementation of the custom PropertySource:
package some.package;
#Order(Ordered.LOWEST_PRECEDENCE)
class StrictSystemEnvironmentProcessor implements EnvironmentPostProcessor {
private static final String PROPERTY_SOURCE_NAME = "STRICT_" + StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME;
#Override
public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
if (environment.getPropertySources().contains(PROPERTY_SOURCE_NAME)) {
return;
}
SystemEnvironmentPropertySource delegate = (SystemEnvironmentPropertySource)environment.getPropertySources()
.get(StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME);
environment.getPropertySources().addLast(new StrictSystemEnvironmentPropertySource(delegate));
}
private static class StrictSystemEnvironmentPropertySource extends SystemEnvironmentPropertySource {
public StrictSystemEnvironmentPropertySource(SystemEnvironmentPropertySource delegate) {
super(PROPERTY_SOURCE_NAME, delegate.getSource());
}
#Override
public Object getProperty(String name) {
if (name.startsWith("!")) {
String variableName = name.substring(1);
Object property = super.getProperty(variableName);
if (property != null) {
return property;
}
throw new IllegalStateException("Environment variable '" + variableName + "' is not set");
}
return null;
}
}
}
Instead of returning null, an exception is thrown for names that start with !.
This META-INF/spring.factories is also required so that Spring initializes our EnvironmentPostProcessor:
org.springframework.boot.env.EnvironmentPostProcessor=some.package.StrictSystemEnvironmentProcessor
Then henceforth, I can write all environment variables substitutions in my configs as ${!FOO} to get strict existance checking.
You can also create a #ConfigurationProperties bean, and decorate it with #Validated and #NotNull. This will throw an exception during startup when the value is not present (or null), e.g.
#Validated
#ConfigurationProperties("my")
public class MyProperties {
#NotNull
private String home;
// getter/setter, or constructor. See #ConstructorBinding.
}
For reference: Spring Boot 2.6 - #ConfigurationProperties Validation.
Note that you may need to add spring-boot-starter-validation, or another validator, depending on your project.
Then, you can just supply it as a dependency when needed, e.g.
#Component
public class AnotherBean {
private final MyProperties myProps;
public AnotherBean(MyProperties myProps) {
this.myProps = myProps;
}
// some code that uses myProps.getHome()
}