[[accessing-web-page-and-browser-information]]
Accessing web page and browser information
------------------------------------------

Vaadin 7 includes a new *Page* class offering access to various
client-side information and events concerning the web page and browser
window in which the Vaadin UI resides. The Page instance corresponding
to a given UI is accessed via the `getPage()` method of the UI or using
a static method `Page.getCurrent()`.

You can access the browser window size and add size change listeners:

[source,java]
....
Page page = someUI.getPage();
page.addBrowserWindowResizeListener(new BrowserWindowResizeListener() {
  public void browserWindowResized(BrowserWindowResizeEvent event) {
    Notification.show("Window width=" + event.getWidth() + ", height=" + event.getHeight());
  }
});
....

You can access the optional fragment part of the location URI and add
fragment change listeners:

[source,java]
....
page.setUriFragment(page.getUriFragment() + "foo");
page.addUriFragmentChangedListener(new UriFragmentChangedListener() {
  public void uriFragmentChanged(UriFragmentChangedEvent event) {
    Notification.show("Fragment=" + event.getUriFragment());
  }
});
....

You can access client browser details:

[source,java]
....
Notification.show("IP" + browser.getAddress() +
                "User-Agent:" + browser.getBrowserApplication() +
                "Linux: " + browser.isLinux());
....

https://demo.vaadin.com/sampler/#foundation/advanced/browser-information[Live
Demo]

Note: If you are using a reverse proxy, you must get the value
`X-Forwarded-For` from request headers. You cannot get a browser name,
but you can check which browser are using.
