I'm using a hierarchy of classes and what I would optimally try to do is have #ManagedBean's that inherit a class that have #ManagedProperty members and #PostConstruct methods.
Specifically, will this work? :
public class A {
#ManagedProperty
private C c;
#PostConstruct
public void init() {
// Do some initialization stuff
}
public C getC() {
return c;
}
public void setC(C c) {
this.c = c;
}
}
#ManagedBean
#SessionScoped
public class B extends A {
// Content...
}
Thanks in Advance!
The #ManagedProperty is inherited and will just work that way. The #PostConstruct will also be inherited, provided that the subclass itself doesn't have a #PostConstruct method. There can namely be only one. So if the subclass itself has a #PostConstruct, then the superclass' one won't be invoked.
So if you override the #PostConstruct in the subclass, then you'd need to explicitly invoke the superclass' one.
public class SuperBean {
#PostConstruct
public void init() {
// ...
}
}
#ManagedBean
public class SubBean extends SuperBean {
#PostConstruct
public void init() {
super.init();
// ...
}
}
Alternatively, provide an abstract method which the subclass must implement (without #PostConstruct!).
public class SuperBean {
#PostConstruct
public void superInit() {
// ...
init();
}
public abstract void init();
}
#ManagedBean
public class SubBean extends SuperBean {
#Override
public void init() {
// ...
}
}
Related
I want to reduce the verbosity of binding a generic interface to several implementations based on TypeLiterals...
I have an interface FieldComputer<T extends ComputeField> where ComputeField is my model interface.
Tried extending a ShortLiteral class (see example below) to reduce the verbosity but it doesn't seem to work. would like to understand why?
// A typical Guice Module
public class ConflationModule implements Module {
// typical overridden configure method
public void configure(Binder binder) {
// Works but is verbose....
bindField_1(binder,
new TypeLiteral<FieldComputer<ComputeFieldImpl>>(){},
FieldComputerImpl.class);
// Doesn't Work
bindField_1(binder,
new ShortLiteral<ComputeFieldImpl>(){},
FieldComputerImpl.class);
// Doesn't Work
bindField_2(binder,
new ShortLiteral<ComputeFieldImpl>(){},
FieldComputerImpl.class);
}
private static class ShortLiteral<CF extends ComputeField> extends TypeLiteral<FieldComputer<CF>>{}
private <CF extends ComputeField> void bindField_1(Binder binder,
TypeLiteral<FieldComputer<CF>> typeLiteral,
Class<? extends FieldComputer<CF>> clazz
) {
binder.bind(typeLiteral).to(clazz);
}
private <CF extends ComputeField> void bindField_2(Binder binder,
ShortLiteral<CF> typeLiteral,
Class<? extends FieldComputer<CF>> clazz
) {
binder.bind(typeLiteral).to(clazz);
}
}
I would suggest you just create TypeLiteral programmatically, here is an example how to do it with different implementations of one interface:
class TypeLiteralModule extends AbstractModule {
#Override
protected void configure() {
customBind(String.class, StringConsumer.class);
customBind(Integer.class, IntegerConsumer.class);
}
private <T> void customBind(Class<T> clazz, Class<? extends Consumer<T>> impl) {
var typeLiteral = (TypeLiteral<Consumer<T>>) TypeLiteral.get(Types.newParameterizedType(Consumer.class, clazz));
bind(impl).in(Singleton.class);
bind(typeLiteral).to(impl);
}
}
class StringConsumer implements Consumer<String> {
#Override
public void accept(String s) {
}
}
class IntegerConsumer implements Consumer<Integer> {
#Override
public void accept(Integer s) {
}
}
Lets say we have A.java interface implemented by AImpl.java and B.java implemented by Bimpl.java
Above classes are binded in two modules as below
Module1 {
bind(A.class).to(AImpl.class);
bind(B.class).to(BImpl.class);
}
Module2 {
Key<A> aKey = Key.get(A.class, AnAnnot.class);
bind(aKey).to(AImpl.class);
Key<B> bKey = Key.get(B.class, AnAnnot.class);
bind(bKey).to(BImpl.class);
}
Class AImpl implements A {
}
Class BImpl implements B {
#Inject
BImpl(A aImpl) {
//??
}
}
BImpl refers to A
For BImpl binded using Annotation, I want corresponding aImpl, binded using Annotation but here I'm getting aImpl which is not binded using Annotation
Please suggest
I'm able to achieve using below pattern. May be there is a more easier way. Happy to know more
A.java
public interface A {
String aMethod();
}
AImpl.java
public class AImpl implements A {
private String moduleName;
public AImpl(String moduleName) {
this.moduleName = moduleName;
}
#Override
public String aMethod() {
return moduleName;
}
}
B.java
public interface B {
String bMethod();
}
Bimpl.java
public class BImpl implements B {
private final A a;
BImpl(A a) {
this.a = a;
}
#Override
public String bMethod() {
return a.aMethod();
}
}
AnAnnot.java
#Target(PARAMETER)
#Retention(RUNTIME)
#BindingAnnotation
public #interface AnAnnot {
}
BProvider.java
public class BProvider implements Provider<B> {
private final A a;
#Inject
BProvider(A a) {
this.a = a;
}
#Override
public B get() {
return new BImpl(a);
}
}
BHavingAnnotatedA.java
public class BHavingAnnotatedA implements Provider<B> {
private final A a;
#Inject
BHavingAnnotatedA(#AnAnnot A a) {
this.a = a;
}
#Override
public B get() {
return new BImpl(a);
}
}
ABModule1.java
public class ABModule1 extends AbstractModule {
#Override
protected void configure() {
bind(A.class).to(AImpl.class);
bind(B.class).toProvider(BProvider.class);
}
}
ABModule2.java
public class ABModule2 extends AbstractModule {
#Override
protected void configure() {
Key<A> aKey = Key.get(A.class, AnAnnot.class);
bind(aKey).to(AImpl.class);
Key<B> bKey = Key.get(B.class, AnAnnot.class);
bind(bKey).toProvider(BHavingAnnotatedA.class);
}
}
In order to initialize the application at startup, I extended ServletContextListener:
#WebListener
public class MyServletContextListener implements javax.servlet.ServletContextListener {
#Override
public void contextInitialized(ServletContextEvent sce) {
... initialization code here
}
#Override
public void contextDestroyed(ServletContextEvent sce) {}
}
Now I want to extract the initialization logic into a standalone StartupManager class, and delegate to this class from MyServletContextListener:
public class StartupManager {
public void performStartup() {
... initialization code here
}
}
I tried to inject StartupManager into ServletContextListener by simply adding #Inject annotation:
#WebListener
public class MyServletContextListener implements javax.servlet.ServletContextListener {
#Inject StartupManager mStartupManager;
#Override
public void contextInitialized(ServletContextEvent sce) {
mStartupManager.performStartup();
}
#Override
public void contextDestroyed(ServletContextEvent sce) {}
}
This did not work - the reference is null when contextInitialized(ServletContextEvent ) is called.
Then I thought that I might have to register a binder:
#ApplicationPath("")
public class MyResourceConfig extends ResourceConfig {
public MyResourceConfig() {
register(new DependencyInjectionBinder());
}
}
public class DependencyInjectionBinder extends AbstractBinder {
#Override
protected void configure() {
bind(StartupManager.class).to(StartupManager.class);
}
}
This did not work either.
My question is how can I perform injection of dependencies into ServletContextListener? Preferably constructor injection, but field injection will also be alright.
It's not going to work, as the servlet listener and Jersey are not linked to the same system. As an alternative, you can use Jersey's Event Listeners. You can implement an ApplicationEventListener where you would be able to initialization and clean up in the same way you would in the servlet listener. You would be able to inject your services into Jersey's listener.
Is there a way to change the implementation of UriInfo that's injected into all the resources and classes? I want to keep most of the implementation the same, but just change one part of it (the part that provides a UriBuilder - I want to provide a different implementation of the UriBuilder).
You can create wrapper around the original UriInfo
public class MyUriInfo implements UriInfo {
private final UriInfo delegate;
public MyUriInfo(UriInfo uriInfo) {
this.delegate = uriInfo;
}
#Override
public String getPath() {
return delegate.getPath();
}
#Override
public UriBuilder getRequestUriBuilder() {
return new MyUriBuilder();
}
...
}
Then just create a Factory to return your custom UriInfo. This Factory will be used by the DI framework to inject the UriInfo.
public class MyUriInfoFactory
extends AbstractContainerRequestValueFactory<MyUriInfo> {
#Override
public MyUriInfo provide() {
return new MyUriInfo(getContainerRequest().getUriInfo());
}
}
Then just create the AbstractBinder and register it with the ResourceConfig
public class Binder extends AbstractBinder {
#Override
protected void configure() {
bindFactory(MyUriInfoFactory.class)
.to(UriInfo.class)
.in(RequestScoped.class)
.proxy(true)
.proxyForSameScope(false)
.ranked(10);
}
}
public class AppConfig extends ResourceConfig {
public AppConfig() {
register(new Binder());
}
}
If you are using web.xml, check out this post.
Now you should be able to just inject it
#GET
public String get(#Context UriInfo uriInfo) {
return uriInfo.getClass().getName();
}
If you want to be able to retain being able to inject the original UriInfo, you can change the binding to
bindFactory(MyUriInfoFactory.class)
.to(MyUriInfo.class) // <--- Change here to MyUriInfo
.in(RequestScoped.class)
.proxy(true)
.proxyForSameScope(false)
.ranked(10);
This way, you would need to inject MyUriInfo
#GET
public String get(#Context MyUriInfo uriInfo) {
return uriInfo.getClass().getName();
}
Doing this, you are still able to inject the original UriInfo if you needed to.
See Also:
Custom Injection and Lifecycle Management
I have a hard time understanding the injection mechanism of Jersey. The JAX-RS Specification (http://jsr311.java.net/nonav/releases/1.1/spec/spec3.html#x3-520005) states that injection via #Context is possible in Application subclasses, root resource classes and providers.
I now have a class that is instantiated at startup and has a method which is called on every request. Inside the method I need access to the current UriInfo object. The problem is, that this method is not called from my code. So I can't pass UriInfo directly to the method.
I actually want to do something like this:
public class MyClass implements ThirdPartyInterface {
// not possible because class is no Application subclass, root resource class or provider
#Context
private UriInfo uriInfo;
public void methodCallebByThirdPartyCode() {
Uri requestUri = uriInfo.getRequestUri();
// do something
}
}
I tried this. Obviously with no success:
public class MyClass implements ThirdPartyInterface {
private UriInfo uriInfo;
public MyClass(UriInfo uriInfo) {
this.uriInfo = uriInfo;
}
public void methodCallebByThirdPartyCode() {
Uri requestUri = uriInfo.getRequestUri();
// do something
}
}
#Provider
#Produces(MediaType.WILDCARD)
public class MyBodyWriter implements MessageBodyWriter<MyView> {
#Context
private UriInfo uriInfo;
private MyClass myClass;
private ThirdPartyClass thirdPartyClass;
public MyBodyWriter() {
// uriInfo is null at this time :(
myClass = new MyClass(uriInfo);
thirdPartyClass = new ThirdPartyClass();
thirdPartyClass.register(myClass);
}
public void writeTo(final MyView view, final Class<?> type, /* and so on */) throws IOException, WebApplicationException {
// execute() calls MyClass#methodCallebByThirdPartyCode()
thirdPartyClass.execute();
}
}
The only workaround I can think of is this. I don't think it's very clean:
public class MyClass implements ThirdPartyInterface {
private UriInfo uriInfo;
public void setUriInfo(final UriInfo uriInfo) {
this.uriInfo = uriInfo;
}
public void methodCallebByThirdPartyCode() {
Uri requestUri = uriInfo.getRequestUri();
// do something
}
}
#Provider
#Produces(MediaType.WILDCARD)
public class MyBodyWriter implements MessageBodyWriter<MyView> {
#Context
private UriInfo uriInfo;
private MyClass myClass;
private ThirdPartyClass thirdPartyClass;
public MyBodyWriter() {
myClass = new MyClass();
thirdPartyClass = new ThirdPartyClass();
thirdPartyClass.register(myClass);
}
public void writeTo(final MyView view, final Class<?> type, /* and so on */) throws IOException, WebApplicationException {
myClass.setUriInfo(uriInfo);
// execute() calls MyClass#methodCallebByThirdPartyCode()
thirdPartyClass.execute();
myClass.setUriInfo(null);
}
}
I hope there is a better solution, but maybe I'm completely on the wrong track.
Thanks!
Late answer, but a good question ... so lets go:
You can use a org.glassfish.hk2.api.Factory and javax.inject.Provider for injections. I don't know since which version this is available, so maybe you have to upgrade your jersery version. For the following samples i used jersey 2.12.
First you have to implement and register/bind a Factory for your MyClass:
MyClassFactory:
import javax.inject.Inject;
import javax.ws.rs.core.UriInfo;
import org.glassfish.hk2.api.Factory;
// ...
public class MyClassFactory implements Factory<MyClass> {
private final UriInfo uriInfo;
// we will bind MyClassFactory per lookup later, so
// the constructor will be called everytime we need the factory
// meaning, uriInfo is also per lookup
#Inject
public MyClassFactory(final UriInfo uriInfo) {
this.uriInfo = uriInfo;
}
#Override
public MyClass provide() {
return new MyClass(uriInfo)
}
#Override
public void dispose(UriInfo uriInfo) {
// ignore
}
}
Registration via ResourceConfig:
import org.glassfish.hk2.api.PerLookup;
import org.glassfish.hk2.utilities.binding.AbstractBinder;
import org.glassfish.jersey.server.ResourceConfig;
// ...
public class MyResourceConfig extends ResourceConfig {
public MyResourceConfig() {
register(new AbstractBinder() {
#Override
protected void configure() {
bindFactory(MyClassFactory.class).to(MyClass.class).in(PerLookup.class);
// ... bind additional factories here
}
});
// ...
}
}
Now you are able to inject MyClass per lookup to providers, resources etc.
But Attention: Afaig there are two approaches and only one will work as eventually aspected for providers ...
import javax.inject.Inject;
import javax.ws.rs.Produces;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
// ...
#Provider
#Produces("application/foo-bar")
public class MyBodyWriter implements MessageBodyWriter<MyView> {
// first approache - don't do it!
// will only injected once, cause MyBodyWriter is only instantiated once
#Inject
private MyClass myClass;
// second approache - works fine!
private final javax.inject.Provider<MyClass> provider;
// MyBodyWriter instantiate once
// get an inject provider here
#Inject
public MyBodyWriter(javax.inject.Provider<MyClass> myClassProvider) {
this.provider = myClassProvider;
}
#Override
public boolean isWriteable(Class<?> t, Type g, Annotation[] a, MediaType m) {
return t == MyView.class;
}
#Override
public long getSize(MyView t, Class<?> c, Type g, Annotation[] a, MediaType m) {
// deprecated by JAX-RS 2.0 and ignored by Jersey runtime
return 0;
}
#Override
public void writeTo(MyView v, Class<?> c, Type t, Annotation[] a, MediaType m, MultivaluedMap<String, Object> s, OutputStream o) throws IOException, WebApplicationException {
// attention: its not per lookup !!!
MyClass myClassDirectInjected = myClass;
System.out.println(myClassDirectInjected); // same instance everytime
// but this is ;)
MyClass myClassFromProvider = provider.get();
System.out.println(myClassFromProvider); // it's a new instance everytime
// ...
}
}
Hope this was somehow helpfull.