I have two Parts lets say A and B. Part A has a function named isDragging which returns boolean.
How can I access the isDragging function in method B ? Should I make the function become static ? Can I rely on Dependency Injection here (if it's possible) ?
Use the EModelService to find Part A by its id:
#Inject
EModelService modelService;
#Inject
MApplication application;
MPart partA = (MPart)modelService.find("part A id", application);
PartAObject myObject = (PartAObject)partA.getObject();
if (myObject.isDragging())
where 'PartAObject' is your part Class (as specified in the model Class URI).
Related
How can I know if a class is annotated with javax.persistence.Entity?
Person (Entity)
#Entity
#Table(name = "t_person")
public class Person {
...
}
PersonManager
#Stateless
public class PersonManager {
#PersistenceContext
protected EntityManager em;
public Person findById(int id) {
Person person = this.em.find(Person.class, id);
return person;
}
I try to do it with instance of as the following
#Inject
PersonManager manager;
Object o = manager.findById(1);
o instanceof Entity // false
however the result is false, shouldn't it be true?
While the existing answers provide a (somehow) working solution, some things should be noted:
Using an approach based on Reflection implies (a) Performance Overhead and (b) Security Restrictions (see Drawbacks of Reflection).
Using an ORM-specific (here: Hibernate) approach risks portability of the code towards other execution environments, i.e., application containers or other customer-related settings.
Luckily, there is a third JPA-only way of detecting whether a certain Java class (type) is a (managed) #Entity. This approach makes use of standardized access to the javax.persistence.metamodel.MetaModel. With it you get the method
Set < EntityType > getEntities();
It only lists types annotated with #Entity AND which are detected by the current instance of EntityManager you use. With every object of EntityType it is possible to call
Class< ? > getJavaType();
For demonstration purposes, I quickly wrote a method which requires an instance of EntityManager (here: em), either injected or created ad-hoc:
private boolean isEntity(Class<?> clazz) {
boolean foundEntity = false;
Set<EntityType<?>> entities = em.getMetamodel().getEntities();
for(EntityType<?> entityType :entities) {
Class<?> entityClass = entityType.getJavaType();
if(entityClass.equals(clazz)) {
foundEntity = true;
}
}
return foundEntity;
}
You can provide such a method (either public or protected) in a central place (such as a Service class) for easy re-use by your application components. The above example shall just give a direction of what to look for aiming at a pure JPA approach.
For reference see sections 5.1.1 (page 218) and 5.1.2 (page 219f) of the JPA 2.1 specification.
Hope it helps.
If the statement
sessionFactory.getClassMetadata( HibernateProxyHelper.getClassWithoutInitializingProxy( Person.class ) ) != null;
is true, than it is an entity.
#NiVer's answer is valid. But, if you don't have a session or sessionFactory at that point you could use Reflection. Something like:
o.getClass().getAnnotation(Entity.class) != null;
I am migrating from org.apache.felix.scr annotations to org.osgi.service.component annotations. I have a set of Components that inherit from a common abstract class. In the felix case, I can use a #Component annotation with the option componentAbstract=true on the super class, and then use #Reference annotation in the super class. I cannot find how to migrate this to osgi annotations.
Is it possible to use Component annotations in a super class of a Component? And if so, what is then the appropriate way to handle the properties and metatype generation?
So, what I am looking for, is something like this
/* No component definition should be generated for the parent, as it is
abstract and cannot be instantiated */
#Component(property="parent.property=parentValue")
public abstract class Parent {
#Reference
protected Service aService;
protected activate(Map<String,Object> props) {
System.out.println("I have my parent property: "+props.get("parent.property"));
#Override
public abstract void doSomething();
}
/* For this class, the proper Component definition should be generated, also
including the information coming from the annotations in the parent */
#Component(property="child.property=childValue")
public class Child extends Parent {
#Activate
public activate(Map<String,Object> props) {
super.activate(props);
System.out.println("I have my child property: "+props.get("child.property"));
}
public void doSomething() {
aService.doSomething();
}
}
By default BND will not process DS annotations in parent classes. You can change that with -dsannotations-options: inherit but please see http://enroute.osgi.org/faq/ds-inheritance.html why you shouldn't!
2021-02-23 UPDATE: It seems like the page mentioned above is no longer available. I don't know if it was moved elsewhere or simply removed but its content (in Markdown format) is still available on GitHub: https://github.com/osgi/osgi.enroute.site/blob/pre-R7/_faq/ds-inheritance.md
I'm currently working on a simple GWT project. One of the things I'd like to do is that when the page loads I can dynamically populate the contents of a ListBox based on certain criteria. I actually don't see any handlers for a ListBox to handle the initial render event but I see change handlers.
How does one populate a ListBox contents with data from the server side on pageload with GWT?
Right now I have a class that implements EntryPoint that has a
final ListBox fooList = new ListBox();
I also have a set of beans but I also have a class implementing RemoteService. Since I can't seem to get direct calls to my user defined packages directly in the EntryPoint (which makes sense) how do I populate that ListBox with server side content on initial page load? Right now I'm using a List but I figure if I cant get that to work I can get a DB call to work...
I've tried things in the EntryPoint like:
for (String name : FOOS) {
fooList.addItem(name, name);
}
However FOOS would derive from a server side data and the EntryPoint is supposed to be largerly limited to what can compile to JS! I can't get user defined classes to be recognized on that side as that string is the result of a set of user defined classes.
I also tried creating a method in the class implementing RemoteService that returns a ListBox. This also didn't compile when I tried to call this method. Perhaps I don't fully understand how to call methods in a RemoteService service implementing class.
I've searched a lot and I can't find anything that clearly explains the fundamentals on this. My background is much more ASP.NET and JSPs so perhaps I'm missing something.
I'm using GWT 2.6 is that is relevant.
The usual procedure is the following:
Create a bean class for the data you want to transmit between client and server. Let's call it MyBean.
Place MyBean in the shared package of your project.
This class has to implement either Serializable or IsSerializable, otherwise GWT will complain that it doesn't know how to transmit it.
Create your RemoteService that contains the method you want to use to transmit MyBean from/to the server.
Once you get your data on the client using an AsyncCallback and your RemoteService, fill the ListBox using your beans, e.g. by calling MyBean#getName() or MyBean#toString().
Success!
I based my example on the GWT sample project ( I named it example), just replace the classes and it should work :
public class Example implements EntryPoint {
/**
* Create a remote service proxy to talk to the server-side Greeting
* service.
*/
private final GreetingServiceAsync greetingService = GWT
.create(GreetingService.class);
/**
* This is the entry point method.
*/
public void onModuleLoad() {
final ListBox listBox = new ListBox();
RootPanel.get("sendButtonContainer").add(listBox);
greetingService.getSomeEntries(new AsyncCallback<String[]>() {
#Override
public void onSuccess(String[] result) {
for (int i = 0; i < result.length; i++) {
listBox.addItem(result[i]);
}
}
#Override
public void onFailure(Throwable caught) {
}
});
}
}
This is our EntryPoint, it creates a listbox and calls the server with a AsyncCallback to get some dynamic data. If the call is successfull (onSuccess), the data is written into the listbox.
The GreetingService interface define the synchronous methods, it is implemented in the GreetingServiceImpl class :
#RemoteServiceRelativePath("greet")
public interface GreetingService extends RemoteService {
String[] getSomeEntries() ;
}
The asynchronous counterpart is the GreetingServiceAsync interface, we used it before to call the server :
public interface GreetingServiceAsync {
void getSomeEntries(AsyncCallback<String[]> callback) ;
}
The GreetingServiceImpl class is located on the server. Here you could call for example a database:
#SuppressWarnings("serial")
public class GreetingServiceImpl extends RemoteServiceServlet implements
GreetingService {
#Override
public String[] getSomeEntries() {
String[] entries = { "Entry 1","Entry 2","Entry 3" };
return entries;
}
}
Now if you want to use some Bean/Pojo between the server and client, replace the String[] in each class/interface with the object name, put the class in the shared package and consider that it implements Serializable/IsSerializable.
I have an issue when I compile the user interface, when i add a method messages.usuario(), Firebug show the error : TypeError: null has no properties
lblUsuario = new Label_2(null.nullMethod()); this is the code of my class :
public class AdministradorMVP implements EntryPoint {
private MessageConstants messages;
#Inject
public void setMensajes(MessageConstants mensajes) {
this.messages = mensajes;
}
private final MyWidgetGinjector injector = GWT.create(MyWidgetGinjector.class);
private Place defaultPlace = new SignInPlace("Admin");
private SimplePanel appWidget = new SimplePanel();
/**
* This is the entry point method.
*/
Label lblUsuario = new Label(messages.usuario());
Label lblNombre = new Label(messages.nombre());
so I can't find the source of the problem, thank you
The GWT compiler generates null.nullMethod() whenever it can statically determine that a particular method is always called on a null reference. In this case, messages has been determined to always be null (either setMensajes is called with a null value or it's not called at all), so messages.usuario() would always throw a NullPointerException, and this is translated into a null.nullMethod() in the generated JavaScript code.
From your code I'm missing the 'boostrap the injection' (see JavaDoc of Ginjector). In other words, you need to trigger the initial inject to take place. Creating MyWidgetGinjector is not enough.
One solution is to add a method void inject(AdministradorMVP entryPoint); to the interface MyWidgetGinjector and in the class AdministradorMVP in onModuleLoad call as (one of) the first statements: injector.inject(this);.
It seems Guice is ignoring my #Provider methods of my module.
I have a class MyModule like this:
public class MyModule extends AbstractModule {
protected void configure() {
bindInterceptor(Matchers.any(), Matchers.annotatedWith(Timed.class), new GuiceEnabledLoggingInterceptor());
bind(OneClass.class).to(OneClassImpl.class);
// And more binding lines...
}
#Provides
public AnotherClassInApi provideMyClass() {
return AnotherClassInApi.getInstance();
}
// And more #Provides methods
}
Main method is
public static void main(String[] args){
ConfigHandler.getInstance().loadConfigWhenNotRunningInsideMicrocontainer();
Injector INJECTOR = Guice.createInjector(new MyModule());
// ...
}
In some other part of the project I have class AnotherClassInApi, which is a very standard singleton plus one method:
public class AnotherClassInApi {
private static final AnotherClassInApi INSTANCE = new AnotherClassInApi();
private AnotherClassInApi() { }
// ... more methods
public static AnotherClassInApi getInstance() {
return INSTANCE;
}
}
Well, I understand that should effectively bind any request for an AnotherClassInApi object to the getInstance() method, but it doesn't work. Funny thing, a breakpoint in the #Provide method is never reached while debugging, but one in the configure method is reached. It seems guice is ignoring my provider annotation, and I think I'm following exactly what Guice guide says about #Provider, so I'm already stuck.
I've been googling around, but can't find anything similar. Any help will be much appreciated.
Thanks!
The concept of Providers (and #Provides methods) is, that they are only called when actually needed. So unless you really use your Injector to create an instance that has an #Inject dependency, your Provider is not ignored, just not used (nor needed).
You can monitor all configured bindings by using "injector.getAllBindings()".
java.util.Map,Binding> getAllBindings()
Returns a snapshot
of this injector's bindings, both explicit and just-in-time. The
returned map is immutable; it contains only the bindings that were
present when getAllBindings() was invoked. Just-in-time bindings are
only present if they have been requested at least once. Subsequent
calls may return a map with additional just-in-time bindings. The
returned map does not include bindings inherited from a parent
injector, should one exist.
This method is part of the Guice SPI and is intended for use by tools
and extensions.