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[[creating-an-application-with-different-features-for-different-clients]]
Creating an application with different features for different clients
---------------------------------------------------------------------
Providing different features for different clients can be done by
creating a specialized UIProvider for the application.
We start by creating the specialized UI's
[source,java]
....
public class DefaultUI extends UI {
@Override
protected void init(VaadinRequest request) {
setContent(
new Label("This browser does not support touch events"));
}
}
....
[source,java]
....
public class TouchUI extends UI {
@Override
protected void init(VaadinRequest request) {
WebBrowser webBrowser = getPage().getWebBrowser();
String screenSize = "" + webBrowser.getScreenWidth() + "x"
+ webBrowser.getScreenHeight();
setContent(new Label("Using a touch enabled device with screen size"
+ screenSize));
}
}
....
We then define an UIProvider which knows what UI the application should
return.
[source,java]
....
public class DifferentFeaturesForDifferentClients extends UIProvider {
@Override
public Class<? extends UI> getUIClass(UIClassSelectionEvent event) {
// could also use browser version etc.
if (event.getRequest().getHeader("user-agent").contains("mobile")) {
return TouchUI.class;
} else {
return DefaultUI.class;
}
}
}
....
Now that we have an `UIProvider` we need to tell Vaadin to use it. This is
most easily done by defining the `UIProvider` class in web.xml instead of
defining a UI class.
[source,xml]
....
<servlet>
<servlet-name>My Vaadin App</servlet-name>
<servlet-class>com.vaadin.server.VaadinServlet</servlet-class>
<init-param>
<description>Vaadin UI</description>
<param-name>UIProvider</param-name>
<param-value>com.example.myexampleproject.DifferentFeaturesForDifferentClients</param-value>
</init-param>
</servlet>
....
Each UI can have its own feature set, layout and theme.
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