History API

The History API allows you to access the browser navigation history from the server-side. It also allow you to modify the navigation history by adding a new entry to it or chaging the current entry. E.g. you can change the current URL that is shown in the brower address bar without invoke any navigation. The history is always bound to the current browser window / frame, so you can access it through the Page object (available through the UI).

Java

History history = UI.getCurrent().getPage().getHistory();

Traversing History

With the methods forward(), back() and go(int) you can programmatically traverse the browser’s history entries. The methods correspond to the user actions on the browser’s back and forward buttons.

Java

history.back(); // navigates back to the previous entry
history.forward(); // navigates forward to the next entry
history.go(-2); // navigates back two entries
history.go(1); // equal to history.forward();
history.go(0); // will reload the current page

Handling user navigation

If you want to manually handle navigation events you can replace it by setting a handler for navigation events using the history.setHistoryStateChangeHandler(HistoryStateChangeHandler). It will be notified when:

• the user navigates back or forward using the browser buttons

• the navigation was done programmatically from server-side java code or client-side JavaScript

• the user clicks a link marked with the router-link attribute

Java

history.setHistoryStateChangeHandler(this::onHistoryStateChange);
private void onHistoryStateChange(HistoryStateChangeEvent event) {
    // site base url is www.abc.com/
    // user navigates back from abc.com/dashboard to abc.com/home
    event.getLocation().getPath(); // returns "home"
}

Changing history

You can update the history by either pushing new entries to the history, or by replacing the current entry. You may optionally provide a json value as the state parameter. This state value will be available via LocationChangeEvent:getState() when the entry is being revisited the next time.

Java

// adds a new history entry for location "home", no state
history.pushState(null, "home");
// replaces the current entry with location "about" and a state object
JsonValue state = Json.create("preview-mode");
history.replaceState(state, "about");