I have an EJB deployed with configurations in ejb-jar.xml and I would like to access
<transaction-type>
configurations in my EJB class during ejbCreate() i.e. Bean or Container as I have to pass this value to my framework for internal work.
Note: I do not want repeat and define an additional env-entry for the same as its already there and I would like to use it
There is no method to determine this information directly. However, you can get at the information indirectly by relying on the fact that EJBContext.getUserTransaction throws an exception for CMT:
#Resource EJBContext ejbContext;
private boolean isBeanManagedTransaction() {
try {
ejbContext.getUserTransaction();
return true;
} catch (IllegalStateException e) {
return false;
}
}
Note, the getUserTransaction method cannot be called from all container callbacks (see the table of allowed operations in the EJB spec), but fortunately, getUserTransaction can be called from ejbCreate/PostConstruct, so this method should work for your purposes.
Related
We have an Aspect in our code that had been PointCut on Hibernate class.
Our Aspect class looks something like this:
#PointCut("(execution(* *.getQueryString(..))" + "|| execution(* *.getQuery(..)))" + "&& (target(org.hibernate.engine.NamedSQLQueryDefinition))")
public void aroundNamedSQLQueryDefinitionGetQuery() {
}
#Around("aroundNamedSQLQueryDefinitionGetQuery")
public String addExtraFilter(ProceedingJoinPoint pjp) throws Exception {
//Logic to add extra filter to the Query.
}
Now we are trying to migrate this code to Quarkus. We have replaced Aspects with Interceptors which were present on code belonging to our modules.
But how do we add Interceptors on Hibernate classes?
Is there an alternate way to achieve this?
A Quarkus extension would allow you to manipulate the Hibernate classes (or your own classes).
To scaffold a basic extension,
mvn io.quarkus.platform:quarkus-maven-plugin:2.10.1.Final:create-extension -N \
-DgroupId=org.you \
-DextensionId=aspectorama
Then, in the [whatever]Processor class that gets created, you could add an AnnotationTransformerBuildItem
#BuildStep
AnnotationsTransformerBuildItem transform() {
return new AnnotationsTransformerBuildItem(new AnnotationsTransformer() {
public boolean appliesTo(org.jboss.jandex.AnnotationTarget.Kind kind) {
return kind == org.jboss.jandex.AnnotationTarget.Kind.METHOD;
}
public void transform(TransformationContext context) {
if ("org.hibernate.engine.NamedSQLQueryDefinition".equals(context.getTarget().asMethod().declaringClass().name()) && ("getQueryString").equals(context.getTarget().asMethod().name()) {
context.transform().add(YourAnnotation.class).done();
}
}
});
}
(I haven't tested that, and I may not have quite the method names you intended. I only did getQueryString not getQuery... but it shows the idea.)
You may also need to tell Quarkus about your interceptor if it's not in the main application codebase:
/**
* Makes the interceptor as a bean so we can access it.
*/
#BuildStep
void beans(BuildProducer<AdditionalBeanBuildItem> producer) {
producer.produce(AdditionalBeanBuildItem.unremovableOf(YourInterceptor.class));
producer.produce(AdditionalBeanBuildItem.unremovableOf(OtherExtraBean.class));
}
It may be that the annotation route isn't the best for your use case, and you could make the changes you needed more directly. It's worth browsing all the Quarkus build items, which are kind of like a library of built-in extension capabilities. For example, you can use #Record to create bytecode.
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()
}
Spring provides bean scope as "Prototype". Means whenever bean is required in application, Spring container will create a fresh/new instance of bean.
Does is follow prototype design pattern also?
Does it create object only once and in subsequent request calls clone() method on created object to create new object?
Also if someone can provide example of prototype in JDK, Spring, Hibernate or any J2EE framework.
No spring does not use cloning to create prototype scoped instances.
Below is the code snippet taken from AbstractBeanFactory.doGetBean() function:
// Create bean instance.
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() {
#Override
public Object getObject() throws BeansException {
try {
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
// Explicitly remove instance from singleton cache: It might have been put there
// eagerly by the creation process, to allow for circular reference resolution.
// Also remove any beans that received a temporary reference to the bean.
destroySingleton(beanName);
throw ex;
}
}
});
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
else if (mbd.isPrototype()) {
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
The createBean method call boils down to below code:
BeanUtils.instantiateClass(constructorToUse);
Spring does not use the Prototype Pattern, it uses reflection.
Plus, in order to use clone() it would have to subclass somehow a bean, because clone() is protected, so it does not use clone() either.
Here is a code fragment from
org.springframework.beans.factory.support.SimpleInstantiationStrategy
where you can see the use of java.lang.reflect.Constructor and java.lang.Class reflection method:
public Object instantiate(RootBeanDefinition beanDefinition, String beanName, BeanFactory owner) {
if (beanDefinition.getMethodOverrides().isEmpty()) {
Constructor<?> constructorToUse;
synchronized (beanDefinition.constructorArgumentLock) {
constructorToUse = (Constructor<?>) beanDefinition.resolvedConstructorOrFactoryMethod;
...
constructorToUse = clazz.getDeclaredConstructor((Class[]) null);
...
}
...
}
...
}
So the term prototype is used to suggest that at every call to getBean, you'll get a new instance with the same properties. This is more than a simple call to a constructor however, because you'll get a bean with all dependencies wired and other properties set, so in a sense it is a prototype. Or at least it fits the concept very well.
I have not dug into Spring source code, but I think Beans with prototype scope in Spring are not created using clone() method because it is not mandatory to implement the Cloneable interface for those beans.
Moreover, suppose it is creating them using clone(). It would then be dangerous if someone is expecting deep copy instead of shallow copy.
You can always test it and find the answer.
No. Spring scopes such as prototype or singletone do not follow strictly design patterns. The naming of scopes was used to intuitively suggest behavior container provides.
This way you can have a "singleton" pattern within the container and create another object outside of the container. Similarly "prototype" pattern does not have to implement "clone" functionality.
You may want to look into this link as well: Singleton design pattern vs Singleton beans in Spring container
More elaborate explanations here:
https://springframework.guru/gang-of-four-design-patterns/prototype-pattern/
I'm using Glassfish 3.1 with JSF2 and EJB stateless to query and write an Oracle DB. The table the user wants to populate in this web application has a primary key. When the user tries to add a new record the ejb method invoking em.persist is called. Now, if the user tries to add a record that has an already used primary key value, I got an exception in the EJB.
I would like to pop up a message to the user indicating that an error in the database occurred but I can't figure out how the JSF managed bean could catch the EJB exception.
Is there any way?
EJB has the concept of system exceptions and application exceptions.
Runtime exceptions, like EntityExistsException are system exceptions. These will among others cause any transaction to be rolled-ed back and cause the EJB instance bean to be discarded (destroyed). Most importantly for your problem, they will be wrapped in an EJBException.
There is no magic surrounding catching these exceptions. Adjusting the code from Petr above,
the following will just work:
Backing bean:
#EJB
private DAOBean daoBean;
public void savePerson(Entity e) {
try {
daoBean.save(e);
} catch (EJBException e) {
FacesMessage message = new FacesMessage("entity is already exists.");
FacesContext.getCurrentInstance.addMessage(null, message);
}
}
EJB:
private EntityManager em;
public void save(Entity e) {
em.persist(e);
}
Note that you can retrieve the cause of the exception to see if was an EntityExistsException or not (omitted above for brevity).
Since you probably have no need to destroy your EJB instance for this case, a better pattern is to define your own exception that inherits from a RuntimeException and is annotated with the #ApplicationException with the rollback attribute set to true.
E.g.
#ApplicationException(rollback = true)
public class MyException extends RuntimeException {
public MyException(Throwable cause) {
super(cause);
}
}
Wrap your EntityExistsException in your EJB into this exception and throw and catch it.
I strongly advise you NOT to use error codes or boolean success/failure as a result. This is a well-known anti pattern and makes your code incredible error prone.
You can create a custom exception class. Let's say UserException with a enum values of possible exception option.
In you EJB you can define your methods as throwable. If you need throw a exception.
In your JSF-SiteBean you only need to use a simple try/catch.
Is exception from type UserException ... get enum reason ... etc.
I have a Grails application that needs to run a strategy that will likely be swapped out over time. I know Spring underlies Grails, so I was wondering if I had access to Spring's IoC container so that I could externalize the actual dependency in an xml file (note: I have never actually done this, but just know of it, so I may be missing something). My goal is to be able to do something like the following:
class SchemaUpdateService {
public int calculateSomething(){
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
IStrategy strat = (IStrategy) ctx.getBean("mystrat");
}
}
And then map the appropriate implementation in the beans.xml file. I assume this is supported in Grails. Does anyone have any documentation on how this would work? Do I really just need the Spring IoC library and it will just work? Thanks!
You define your beans in resources.xml or resources.groovy. The grails documentation is very clear about how to access the Spring application context.
You can access the application context from any Grails artefact using
ApplicationContext ctx = grailsApplication.mainContext
You can then use this to retrieve whichever beans you're interested in:
IStrategy strat = (IStrategy) ctx.getBean("mystrat")
In classes that don't have access to grailsApplication, you could use a helper such as the following to access the application context and the beans therein
class SpringUtils {
static getBean(String name) {
applicationContext.getBean(name)
}
static <T> T getBean(String name, Class<T> requiredType) {
applicationContext.getBean(name, requiredType)
}
static ApplicationContext getApplicationContext() {
ApplicationHolder.application.mainContext
}
}
However, this should only be necessary if you need to retrieve different implementations of the same bean at runtime. If the required bean is known at compile-time, just wire the beans together in resources.xml or resources.groovy
First of all, you want to define your strategy in your grails-app/conf/spring/resources.groovy:
beans = {
myStrat(com.yourcompany.StrategyImpl) {
someProperty = someValue
}
}
Then, you simply def the a property with the same name into your service:
class SomeGrailsService {
def myStrat
def someMethod() {
return myStrat.doSomething()
}
}
In any Grails artefact (such as services and domain classes), Grails will automatically give the myStrat property the correct value. But don't forget, in a unit test you'll have to give it a value manually as the auto-wiring does not happen in unit tests.
Outside of a Grails artefact, you can use something like:
def myStrat = ApplicationHolder.application.mainContext.myStrat
In Grails 2.0, Graeme et al are deprecating the use of the *Holder classes (such as ApplicationHolder and ConfigurationHolder), so I'm not quite sure what the Grails 2.0 approach would be...