Vaadin CDI

https://vaadin.com/docs/-/part/framework/advanced/advanced-cdi.html

Quick Setup

Add dependency to Maven POM

                <dependency>

                        <groupId>javax</groupId>

                        <artifactId>javaee-api</artifactId>

                        <version>7.0</version>

                </dependency>

                <dependency>

                        <groupId>com.vaadin</groupId>

                        <artifactId>vaadin-cdi</artifactId>

                        <version>LATEST</version>

                </dependency>

Add empty file /src/main/webapp/WEB-INF/beans.xml

Convert UI class to CDIUI style

(1) Add @CDIUI("") to class (just above @Theme)

(2) Remove generated VaadinServlet class

@WebServlet(urlPatterns = "/*", name = "RootUIServlet", asyncSupported = true)

@VaadinServletConfiguration(ui = RootUI.class, productionMode = false)

public static class RootUIServlet extends VaadinServlet {

}

Overview

First, use a Java EE container (I'm working on WildFly)

Install: add dependency from Maven (both Vaadin CDI Add-on and Java EE API)

Preparing for CDI

• May need beans.xml in WEB-INF
• should NOT have servlet extending VaadinServlet (different from sample and template)

UI

@CDIUI("")

Normally need not path (so under context)

Scopes

• Java EE scopes
  • WARNING:
    • When using proxies, be aware that it is not guaranteed that the hashCode() or equals() will match when comparing a proxy to its underlying instance. It is imperative to be aware of this when, for example, adding proxies to a Collection.
    • You should avoid using normal scopes with Vaadin components, as proxies may not work correctly within the Vaadin framework. If Vaadin CDI plugin detects such use, it displays a warning such as the following:
    • INFO: The following Vaadin components are injected into normal scoped contexts:
• Add-on provided scopes (com.vaadin.cdi)
  • UI Scoped - identified within a UI instance
    • @UIScoped (non-proxy version)
    • @NormalUIScoped (proxy version)
  • View Scoped - lifecycle starts when user navigates to a view and ends when navigate out
    • @ViewScoped
    • @NormalViewScoped
  • Proxy / not proxy
    • Proxy
      • not guaranteed that hashCode() or equals() will match when comparing proxy to its underlying instance
    • Not proxy
      • circular references NOT work
      • CDI interceptors and decorators NOT work
• Deploying CDI UIs and Servlets (see doc)

View Navigation

The addon manages CDI views with a special view provider and enables view scoping

Preparing the UI for CDI Navigation

@CDIUI("mycdiui")

public class MyCDIUI extends UI {

    @Inject

    CDIViewProvider viewProvider;

    @Override

    protected void init(VaadinRequest request) {

        Navigator navigator = new Navigator(this, this);

        navigator.addProvider(viewProvider);

        // Navigate to start view

        navigator.navigateTo("");

    }

}

• inject CDIViewProvider
• add it for the navigator

View

@CDIView("main")

public class MainView extends CustomComponent implements View {

• CDIView annotate managed view and optionally specify a name
• if view name not provided, derived ("MyFunnyView" -> "my-funny")
• optionally @CDIView(value="myview", supportsParameters=true) allows enter() method gets the URI fragment & the parameter
  • #!myview/someparameter
  • getUI().getNavigator().navigateTo("myview/someparameter");
• optionally @CDIView(value="myview", uis={MyCDIUI.class}) when multiple UI
• @CDIView @UIScoped - makes the view retain the same instance when user navigates away and back to the view

Event

Producer:

class InputPanel extends Panel {     @Inject     private javax.enterprise.event.Event<MyEvent> event;      public InputPanel() {         super("Input");          TextField editor = new TextField();         Button save = new Button("Save", e -> // Java 8             event.fire(new MyEvent(editor.getValue())));          setContent(new VerticalLayout(editor, save));     } }

Consumer:

@UIScoped class DisplayPanel extends Panel {     Label display = new Label("-nothing to display-");      public DisplayPanel() {         super("Display");         setContent(display);     }      void myEventObserver(@Observes MyEvent event) {         display.setValue("Observed: " + event.getName());     } }

Communications between UIs (skipped for now)