Today I added Guice to my Java FX Application. The main goal was to replace the singletons I had with Injection and break up dependencies.
So far everything worked fine, this is the code I have to start a new Scene:
public class App extends Application{
public static void main(String[] args){
launch(args);
}
#Override
public void start(Stage primaryStage) throws Exception {
final String LANGUAGE_BUNDLE = "myBundlePath";
final String FXML = "myFXMLPath";
try {
ResourceBundle resourceBundle = ResourceBundle.getBundle(LANGUAGE_BUNDLE, Locale.GERMAN, this.getClass().getClassLoader());
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource(FXML), resourceBundle, new JavaFXBuilderFactory(), getGuiceControllerFactory());
primaryStage.setScene(new Scene(fxmlLoader.load()));
primaryStage.show();
}catch (IOException ex) {
ex.printStackTrace();
}
}
private Callback<Class<?>, Object> getGuiceControllerFactory(){
Injector injector = Guice.createInjector(new GuiceModule());
return new Callback<Class<?>, Object>() {
#Override
public Object call(Class<?> clazz) {
return injector.getInstance(clazz);
}
};
}
}
My Guice Module looks like this:
public class GuiceModule extends AbstractModule {
#Override
protected void configure() {
bind(ITester.class).to(Tester.class);
bind(ISecondTest.class).to(SecondTest.class);
}
}
Please note that i substituted the paths for the ressource bundle and the fxml file as they would have revealed my identity. But loading and everything works, so this shouldn't be a problem ;)
Now the problem is, that I want to instantiate a new view with a button click in a different view. The second view should display a more detailed version of the data in view 1.
Everything that I need to pass to the second view is an Integer (or int), but I have absolutely no clue on how to do this.
I have the standard FX setup with:
View.fxml (with a reference to the ViewController)
ViewController.java
Model.java
ViewModel.java
The ViewController then binds to properties offered by the ViewModel.
I need the int to choose the correct model.
Everything I could find was about the Annotation #Named but as far as I can see, this wouldn't be usable to inject dynamic data.
Could you please give me a hint what this what I want to do is called?
Or long story short: How can I inject a variable, chosen by a different view, in a second ViewController, and leaving the rest in the standard FX-way?
Any help appreciated and thanks in advance!
Regards, Christian
After trying around a bit more, it seems like I found a solution by myself!
However, it "feels" ugly what I'm doing, so I'd like to have some confirmation ;)
First the theory: Guice supports "AssistedInject". This is, when a class can not be constructed by a default constructor. In order to be able to use AssistedInject, you have to download the extension (I downloaded the jar from maven repository).
What AssistedInject does for you is that it allows you to specify a factory which builds the variable for you. So here is what I have done:
First, create an interface for the class which you want to use later, in my case:
public interface IViewController {
}
Second, create an interface for the factory. Important: you do not have to implement the factory
public interface IControllerFactory {
ViewController create(#Assisted int myInt);
}
Third, add the constructor with the corresponding parameters to your class which you want to instantiate later, and let it implement the interface you created like so:
public class ViewController implements IViewController{
#AssistedInject
public ViewController(#Assisted int i){
final String LANGUAGE_BUNDLE = "languageBundle";
final String FXML = "View.fxml";
try{
ResourceBundle resourceBundle = ResourceBundle.getBundle(LANGUAGE_BUNDLE, Locale.GERMAN, this.getClass().getClassLoader());
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource(FXML), resourceBundle, new JavaFXBuilderFactory());
fxmlLoader.setController(this);
Stage second = new Stage();
second.setScene(new Scene(fxmlLoader.load()));
second.show();
}catch (IOException e){
e.printStackTrace();
}
System.out.println("ViewController constructor called with: " + i);
}
Here are a few things to note:
The annotation "#AssistedInject" for the method
The annotation "#Assisted" for the parameter which we want to supply externally
we set the controller for the loader manually (with fxmlLoader.setController(this);)
I had to remove the controller configuration in the fxml file, so no "fx:controller" in the fxml!
Next we need to add a variable into the class from where we want to instantiate the other class:
#Inject
IControllerFactory controllerFactory;
We can use it in the class like so:
controllerFactory.create(3)
Note: we call the method "create" which we never implemented in the ViewController class! Guice knows it has to call the constructor - magic
As last step, we need to add the connection to our context in our GuiceModule, like so:
#Override
protected void configure(){
install(new FactoryModuleBuilder()
.implement(IPagingDirectoryViewController.class, PagingDirectoryViewController.class)
.build(IPagingDirectoryControllerFactory.class));
}
Note I got the error: Cannot resolve method 'implement java.lang.Class<"The interface class">, java.lang.Class<"The implementing class">'. This was because I forgot to let my Controller class implement the interface.
Okay, so that's how I got it working.
As I said however, I'd be really happy about some opinions!
Regards, Christian
In your Module Configuration you could simply add a Provider Method for FXMLLoader, in which you assign Guices 'injector.getInstance()' as ControllerFactory for the loader.
#Provides
public FXMLLoader getFXMLLoader(com.google.inject.Injector injector) {
FXMLLoader loader = new FXMLLoader();
loader.setControllerFactory(injector::getInstance);
return loader;
}
All you have to do now, is to bind your ViewControllers in the configure() method of your module configuration.
// for example:
bind(ViewController.class);
And make sure the controller class is properly bound in your fxml file.
fx:controller="your.package.ViewController"
Now you simply use your injector to get an instance of FXMLLoader.
Related
I want to set some non-UI fields in the controller before the initialize method of the controller gets called automatically upon creation. As I understand it, the way to do it is to provide custom ControllerFactory, since initialize() gets called after ControllerFactory returns the created object. I wanted to use the following code as per this answer:
FXMLLoader loader = new FXMLLoader(mainFXML); // some .fxml file to load
loader.setControllerFactory(param -> {
Object controller = null;
try {
controller = ReflectUtil.newInstance(param); // this is default behaviour
} catch (InstantiationException | IllegalAccessException e) {
e.printStackTrace();
}
if (controller instanceof Swappable) {
((Swappable) controller).setSwapper(swapper); // this is what I want to add
}
return controller;
});
However, the ReflectUtil class (which is used in default setControllerFactory method) is part of com.sun.reflect.misc package, which I am not able to use, since compiling fails with error: package sun.reflect.misc does not exist.
As I understand it, I can't use sun packages, since this is not public API. So the question is: what do I do? I can't find any other examples of this, only the ones with ReflectUtil and, well, I want my ControllerFactory to comply with default workflow of JavaFX with #FXML annotations and all that, is this possible with some other DI framework like Jodd Petite, for example? Is there some other way to set the field? (other than to synchronize on it and wait in initialize() until the setter method gets called from other thread).
Full code on github for context.
If you want to create an instance via reflection then you need to use Class.getConstructor(Class...)1 followed by Constructor.newInstance(Object...).
FXMLLoader loader = new FXMLLoader(/* some location */);
loader.setControllerFactory(param -> {
Object controller;
try {
controller = param.getConstructor().newInstance();
} catch (ReflectiveOperationException ex) {
throw new RuntimeException(ex);
}
if (controller instanceof Swappable) {
((Swappable) controller).setSwapper(swapper);
}
return controller;
}
This code requires that your controller class has a public, no-argument constructor. If you want to inject your dependencies through the constructor you could do something like:
FXMLLoader loader = new FXMLLoader(/* some location */);
loader.setControllerFactory(param -> {
Object controller;
try {
if (Swappable.class.isAssignableFrom(param)) {
controller = param.getConstructor(Swapper.class).newInstance(swapper);
} else {
controller = param.getConstructor().newInstance();
}
} catch (ReflectiveOperationException ex) {
throw new RuntimeException(ex);
}
return controller;
}
This code assumes that all subclasses of Swappable have a public, single-argument constructor that takes a Swapper.
If you want to get a non-public constructor you'll need to use Constructor.getDeclaredConstructor(Class...). Then you'd need to call setAccessible(true) on the Constructor before invoking it.
Couple things to remember if using Jigsaw modules (Java 9+) and this controller factory code is not in the same module as the controller class. Let's say the controller factory code is in module foo and the controller class is in module bar:
If using a public controller with a public constructor then bar must exports the controller class' package to at least foo
If using a non-public controller and/or constructor then the same thing must happen but with opens instead of exports
Otherwise an exception will be thrown.
1. If using a no-argument (not necessarily public) constructor you can bypass getConstructor and call Class.newInstance() directly. However, please note that this method has issues and has be deprecated since Java 9.
Personally, using reflection for my own code is a sign of bad design.
Here's a suggestion that uses FXML mechanisms to inject a user instance of an object. For this purpose, an object is created that describes the context in which the application works. Object user entities are registered in this object. This imposes some constraint on users not to implement a direct interface but to inherit an abstract class that will implement the logic of registering the instance in the context.
public interface Swapper {
}
public abstract class AbstractSwapper implements Swapper {
public AbstractSwapper() {
ApplicationContext.getInstance().setSwapper(this);
}
}
public class ApplicationContext {
private static ApplicationContext instance;
private Swapper swapper;
private ApplicationContext() {
}
public synchronized static ApplicationContext getInstance() {
if(instance == null) {
instance = new ApplicationContext();
}
return instance;
}
public synchronized static Swapper swapperFactory() {
Swapper swapper = getInstance().getSwapper();
if(swapper == null) {
swapper = new AbstractSwapper() {
};
getInstance().setSwapper(swapper);
}
return swapper;
}
public Swapper getSwapper() {
return swapper;
}
public void setSwapper(Swapper swapper) {
this.swapper = swapper;
}
}
In this case, the FXML file can be used fx:factory to use the swapper instance registered in ApplicationContext. Thus, FXMLLoader will inject the instance directly into the controller.
<GridPane fx:controller="sample.Controller" xmlns:fx="http://javafx.com/fxml" >
<fx:define>
<ApplicationContext fx:factory="swapperFactory" fx:id="swapper"/>
</fx:define>
</GridPane>
and sample.Controller
public class Controller {
#FXML
private Swapper swapper;
}
Another solution is for the controller to initialize the fields using the ApplicationContext directly. So the swapper field does not bind to the FXML file.
public class Controller {
private Swapper swapper;
#FXML
private void initialize() {
swapper = ApplicationContext.swapperFactory();
}
}
In both versions, the user simply has to create an instance of AbstractSwapper before using FXMLLoader.
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception{
AbstractSwapper s = new AbstractSwapper() {
};
Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(root, 300, 275));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Also, there is an option to use FXMLLoader to inject the object. In this case it goes through fx:reference or through fx:copy (if you have copy constructor)
I was hoping someone would be able to explain to me exactly why SceneBuilder is so tempermental when it comes to importing custom controls.
Take for example a relatively simple custom control (As only an example):
public class HybridControl extends VBox{
final private Controller ctrlr;
public CustomComboBox(){
this.ctrlr = this.Load();
}
private Controller Load(){
final FXMLLoader loader = new FXMLLoader();
loader.setRoot(this);
loader.setClassLoader(this.getClass().getClassLoader());
loader.setLocation(this.getClass().getResource("Hybrid.fxml"));
try{
final Object root = loader.load();
assert root == this;
} catch (IOException ex){
throw new IllegalStateException(ex);
}
final Controller ctrlr = loader.getController();
assert ctrlr != null;
return ctrlr;
}
/*Custom Stuff Here*/
}
And then you have the Controller class here:
public class Controller implements Initializable{
/*FXML Variables Here*/
#Override public void initialize(URL location, ResourceBundle resources){
/*Initialization Stuff Here*/
}
}
This works just fine. The .jar compiles fine, SceneBuilder reads the .jar just fine, it imports the control just fine, which is great.
The thing that irks me is that it requires two separate classes to accomplish, which is not THAT big of a deal except that I feel like this should be doable with just a single class.
I have it as above now, but I've tried two other ways that both fail (SceneBuilder won't find and let me import the controls) and I was hoping someone would tell me why so I can get on with my life.
In the second case I attempted a single class which extended a VBox and implemented Initializable:
public class Hybrid extends VBox implements Initializable{ /*In this case the FXML file Controller would be set to this class.*/
/*FXML Variables Here*/
public Hybrid(){
this.Load();
}
private void Load(){
final FXMLLoader loader = new FXMLLoader();
loader.setRoot(this);
loader.setClassLoader(this.getClass().getClassLoader());
loader.setLocation(this.getClass().getResource("Hybrid.fxml"));
try{
final Object root = loader.load();
assert root == this;
} catch (IOException ex){
throw new IllegalStateException(ex);
}
assert this == loader.getController();
}
#Override public void initialize(URL location, ResourceBundle resources){
/*Initialization Stuff Here*/
}
}
This makes PERFECT sense to me. It SHOULD work, at least in my head, but it doesn't. The jar compiles fine, and I'd even wager it would work perfectly fine in a program, but when I try to import the .jar into Scene Builder, it doesn't work. It's not present in the list of importable controls.
So... I tried something different. I tried nesting the Controller class within the Control class:
public class Hybrid extends VBox{ /*In this case the FXML Controller I had set to Package.Hybrid.Controller*/
final private Controller ctrlr
public Hybrid(){
this.ctrlr = this.Load();
}
private Controller Load(){
/*Load Code*/
}
public class Controller implements Initializable{
/*Controller Code*/
}
}
This didn't work either. I tried it public, private, public static, private static, none of them worked.
So why is this the case? Why does SceneBuilder fail to recognize a custom control unless the Control class and the Controller class are two separate entities?
EDIT:
Thanks to James_D below I was able to get an answer AND make custom controls work the way I would like. I was also able to create a generic Load method that works for all custom classes if the name of the Class is the same as the name of the FXML file:
private void Load(){
final FXMLLoader loader = new FXMLLoader();
String[] classes = this.getClass().getTypeName().split("\\.");
String loc = classes[classes.length - 1] + ".fxml";
loader.setRoot(this);
loader.setController(this);
loader.setClassLoader(this.getClass().getClassLoader());
loader.setLocation(this.getClass().getResource(loc));
try{
final Object root = loader.load();
assert root == this;
} catch (IOException ex){
throw new IllegalStateException(ex);
}
assert this == loader.getController();
}
Just thought I would share that. Note, again, that it only works if, for example, your class was named Hybrid, and your FXML file was named Hybrid.fxml.
Your second (and third) version won't work at all (SceneBuilder or no SceneBuilder), because the assertion
this == loader.getController()
will fail. When you call loader.load() the FXMLLoader sees the fx:controller="some.package.Hybrid" and creates a new instance of it. So now you have two instances of the Hybrid class: the one which invoked load on the FXMLLoader and the one which is set as the controller of the loaded FXML.
You need to remove the fx:controller attribute from the FXML file, and set the controller directly in your code, as in the documentation:
private void Load(){
final FXMLLoader loader = new FXMLLoader();
loader.setRoot(this);
loader.setClassLoader(this.getClass().getClassLoader());
loader.setLocation(this.getClass().getResource("Hybrid.fxml"));
// add this line, and remove the fx:controller attribute from the fxml file:
loader.setController(this);
try{
final Object root = loader.load();
assert root == this;
} catch (IOException ex){
throw new IllegalStateException(ex);
}
assert this == loader.getController();
}
Experimenting with SceneBuilder, it seems it will attempt to create custom controls by calling their no-arg constructor, and expects that to complete without creating an exception. It does seem like it's not able to handle injecting #FXML annotated values correctly in this particular scenario. I would recommend filing a bug at jira for this.
As a workaround, you will probably have to write your code so that executing the no-arg constructor completes without throwing an exception even if the #FXML-annotated fields are not injected. (Yes, this is a pain.)
I'm new to Java and I'm jumping right in the deep end and using Guice in a project but I can't work out how to bind different values to a constructor based on what parent object the current object will be injected into.
In my code I want to be able to pass in the path to some XSLT files in the constructor of the MessageTransformer but these should be different depending on what it's being injected into.
public class MessageTransformer {
public MessageTransformer(String XsltRequestPath, String XsltReplyPath {
....
}
}
public class SomeClassThatTransformsMessages {
public SomeClassThatTransformsMessages(Transformer transformer) {
....
}
public class SomeOtherClassThatTransformsMessages {
public SomeOtherClassThatTransformsMessages(Transforms transformer) {
....
}
}
So if I was doing it manually I'm trying to recreate the following:
variable1 = new SomeClassThatTransformsMessages (new Transformer("fileA", "fileB"));
variable2 = new SomeOtherClassThatTransformsMessages (new Transformer("fileC", "fileD"));
I don't think I can use the #Named attribute on the transformer but i can possibly use that on the parent classes but not sure how to wire up the files.
I've looked at all the bindings help but none appear to match.
Thanks
Im writing a component using Google Guice that lives next to a web application that does not use any dependency injection tool.
The Guice Module in the component has a few "fixed" bindings that will not change and a couple that are dynamic since they change in every request from the web application.
The easy (and bad) way that I solved this is that everytime that the web application asks the component to do something for the first time, the component builds the new Guice Module, creates the instance and returns it to the web app:
public static X init(#NotNull final Foo perRequestObject, #NotNull final Bar perRequestObject2)
{
final Injector injector = Guice.createInjector(new AbstractModule()
{
#Override
protected void configure()
{
install(new NonChanging Module());
bind(Foo.class).toInstance(perRequestObject);
bind(Bar.class).toInstance(perRequestObject2);
}
});
return return injector.getInstance(X.class);
}
I think that this is a bad approach since building the Injector per request is expensive. What I would like to have is an injector already created that I can override at runtime. I found some stuff around:
1- Override the dynamic bindings (answer https://stackoverflow.com/a/531110/1587864). This still needs to create a new injector so I would have the same problem.
2- Implement some kind of Factory that is already binded in the Injector and has the ability to access the "dynamic" properties that come from the web application and are per request.
I'm not sure how to implement the second one, does this concept exist in Guice?
Thanks
As the comments say, the full proper solution is a Scope. Assuming you've copied the implementation of SimpleScope from this article into your project, then here's what I'd do in your component. As you do above, I assume Foo and Bar are the objects you need created on a per-request basis, and X is the class of the thing you ultimately need Guice to create. I assume further that X has on it a method called doTheActualRequestLogic that is the method you wish to call to ultimately return back to the servlet:
public class MyWebComponent
{
private final Provider<X> theGuiceCreatedObject;
private final SimpleScope perRequestScope;
public MyWebComponent() {
perRequestScope = new SimpleScope();
Injector injector = Guice.createInjector(new AbstractModule()
{
#Override
protected void configure()
{
install(new NonChangingModule());
bind(Foo.class).toProvider(SimpleScope.seededKeyProvider())
.in(perRequestScope);
bind(Bar.class).toProvider(SimpleScope.seededKeyProvider())
.in(perRequestScope);
}
});
theGuiceCreatedObject = injector.getProvider(X.class);
}
// I assume methods called makeFoo and makeBar that can make
// a Foo or Bar for a request
// called by the web service to say "handle this request"
public RequestResult handleRequest(DataToMakeFooAndBarWith requestData) {
try {
perRequestScope.enter();
perRequestScope.seed(Foo.class, makeFoo(requestData));
perRequestScope.seed(Bar.class, makeBar(requestData));
return theGuiceCreatedObject.get().doTheActualRequestLogic(requestData);
} finally {
perRequestScope.exit();
}
}
}
I have a JavaFX application where I would like to introduce Guice because my Code
is full of factorys right now, only for the purpose of testing.
I have one use case where i have a controller class of a certain view.
This controller class has a viewmodel and I pass the model to the viewmodel via
the constructor of the controller class.
In the controller class I have a contactservice object that provides the edit/save/delete operations.
As of now I have an interface of that object and provide an implementation and a Mock. This object can be retrieved by a Factory.getInstance() method.
What I want to do is something like this:
public class NewContactController implements Initializable {
// ------------------------------------------------------------------------
// to inject by guice
// ------------------------------------------------------------------------
private ContactService contactService;
#Inject
public void setContactService(ContactService srv) {
this.contactService = srv;
}
// edit window
public NewContactController(Contact c) {
this.viewModel = new NewContactViewModel(c);
}
// new window
public NewContactController() {
this.viewModel = new NewContactViewModel();
}
#FXML
void onSave(ActionEvent event) {
//do work like edit a contcat,
contactService.editContact(viewModel.getModelToSave());
}
#Override
public void initialize(URL location, ResourceBundle resources) {
// bind to viewmodel---------------------------------------------------
}
}
How can I achive this? Is it a good a idea to do something like that?
While I was searching for a solution I found fx-guice and similar frameworks but how can i combine these two?
Specially how can I let this fields be injected AND instanciate the controller myself or at least give it some constructor args?
I don't use Guice, but the simplest approach would appear to be just to use a controller factory on the FXMLLoader. You can create a controller factory that instructs the FXMLLoader to use Guice to initialize your controllers:
final Injector injector = Guice.createInjector(...);
FXMLLoader loader = new FXMLLoader(getClass().getResource(...));
loader.setControllerFactory(new Callback<Class<?>, Object>() {
#Override
public Object call(Class<?> type) {
return injector.getInstance(type);
}
});
// In Java 8, replace the above with
// loader.setControllerFactory(injector::getInstance);
Parent root = loader.<Parent>load();
There's a good DI framework for javaFX called afterburner.fx. Check it out, I think it's the tool you're looking for.
Assuming you (could) instantiate the controller by hand/guice and not from the FXML, you could use https://github.com/google/guice/wiki/AssistedInject if you need to pass any non DIable parameter to the constructor. You would then set the controller manually to the FXMLLoader with .setController(this) and load the FXML file in the constructor of the controller.
Not sure if there are any drawbacks, but this kind of system seems to work for me :)
To use JavaFx with Guice :
Extend javafx.application.Application & call launch method on that class from the main method. This is the application’s entry point.
Instantiate dependency injection container of your choice. E.g. Google Guice or Weld.
In application’s start method, instantiate FXMLLoader and set it’s controller factory to obtain controllers from the container. Ideally obtain the FXMLLoader from the container itself, using a provider. Then give it an .fxml file resource. This will create content of the newly created window.
Give the Parent object instantiated in previous step to Stage object (usually called primaryStage) supplies as an argument to the start(Stage primaryStage) method.
Display the primaryStage by calling it’s show() method.
Code Example MyApp.java
public class MyApp extends Application {
#Override
public void start(Stage primaryStage) throws IOException {
Injector injector = Guice.createInjector(new GuiceModule());
//The FXMLLoader is instantiated the way Google Guice offers - the FXMLLoader instance
// is built in a separated Provider<FXMLLoader> called FXMLLoaderProvider.
FXMLLoader fxmlLoader = injector.getInstance(FXMLLoader.class);
try (InputStream fxmlInputStream = ClassLoader.getSystemResourceAsStream("fxml\\login.fxml")) {
Parent parent = fxmlLoader.load(fxmlInputStream);
primaryStage.setScene(new Scene(parent));
primaryStage.setTitle("Access mini Stock App v1.1");
primaryStage.show();
primaryStage.setOnCloseRequest(e -> {
System.exit(0);
});
} catch (IOException ex) {
ex.printStackTrace();
}
}
public static void main(String[] args) {
launch();
}
}
Then FXMLLoaderProvider.java
public class FXMLLoaderProvider implements Provider<FXMLLoader> {
#Inject Injector injector;
#Override
public FXMLLoader get() {
FXMLLoader loader = new FXMLLoader();
loader.setControllerFactory(p -> {
return injector.getInstance(p);
});
return loader;
}
}
Thanks to mr. Pavel Pscheidl who provided us with this smart code at Integrating JavaFX 8 with Guice