---
title: Portlet UI
order: 4
layout: page
---

[[portal.ui]]
= Portlet UI

A portlet UI is just like in a regular Vaadin application, a class that extends
[classname]#com.vaadin.ui.UI#.


----
@Theme("myportlet")
public class MyportletUI extends UI {
    @Override
    protected void init(VaadinRequest request) {
        final VerticalLayout layout = new VerticalLayout();
        layout.setMargin(true);
        setContent(layout);

        Button button = new Button("Click Me");
        button.addClickListener(new Button.ClickListener() {
            public void buttonClick(ClickEvent event) {
                layout.addComponent(
                        new Label("Thank you for clicking"));
            }
        });
        layout.addComponent(button);
    }
}
----

If you created the project as a Servlet 3.0 project, the generated UI stub
includes a static servlet class annotated with [classname]#@WebServlet#, as
described in
<<dummy/../../../framework/getting-started/getting-started-first-project#getting-started.first-project.exploring,"Exploring
the Project">>.


----
    @WebServlet(value = "/*", asyncSupported = true)
    @VaadinServletConfiguration(productionMode = false,
                                ui = MyportletUI.class)
    public static class Servlet extends VaadinServlet {
    }
----

This enables running the portlet UI in a servlet container while developing it,
which may be easier than deploying to a portal. For Servlet 2.4 projects, a
[filename]#web.xml# is created.

The portlet theme is defined with the [classname]#@Theme# annotation as usual.
The theme for the UI must match a theme installed in the portal. You can use any
of the built-in themes in Vaadin. For Liferay theme compatibility, there is a
special [literal]#++liferay++# theme. If you use a custom theme, you need to
compile it to CSS with the theme compiler and install it in the portal under the
[filename]#VAADIN/themes# context to be served statically.

In addition to the UI class, you need the portlet descriptor files, Vaadin
libraries, and other files as described later.
<<figure.portal.helloworld.project>> shows the complete project structure under
Eclipse.

[[figure.portal.helloworld.project]]
.Portlet Project Structure in Eclipse
image::img/liferay-project.png[]

Installed as a portlet in Liferay from the [guilabel]#Add Application# menu, the
application will show as illustrated in <<figure.portal.helloworld>>.

[[figure.portal.helloworld]]
.Hello World Portlet
image::img/liferay-helloworld.png[]