本文整理了Java中com.vaadin.flow.component.UI类的一些代码示例，展示了UI类的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。UI类的具体详情如下：
包路径：com.vaadin.flow.component.UI
类名称：UI

UI介绍

[英]The topmost component in any component hierarchy. There is one UI for every Vaadin instance in a browser window. A UI may either represent an entire browser window (or tab) or some part of a html page where a Vaadin application is embedded.

The UI is the server side entry point for various client side features that are not represented as components added to a layout, e.g notifications, sub windows, and executing javascript in the browser.

When a new UI instance is needed, typically because the user opens a URL in a browser window which points to e.g. VaadinServlet, the UI mapped to that servlet is opened. The selection is based on the UI init parameter.

After a UI has been created by the application, it is initialized using #init(VaadinRequest).
[中]任何组件层次结构中最顶层的组件。浏览器窗口中的每个Vaadin实例都有一个UI。UI可以代表整个浏览器窗口（或选项卡），也可以代表嵌入Vaadin应用程序的html页面的某个部分。
UI是各种客户端功能的服务器端入口点，这些功能不表示为添加到布局中的组件，例如通知、子窗口和在浏览器中执行javascript。
当需要一个新的UI实例时，通常是因为用户在浏览器窗口中打开一个指向例如VaadinServlet的URL，映射到该servlet的UI就会打开。选择基于UIinit参数。
应用程序创建UI后，将使用#init（VaadinRequest）对其进行初始化。

代码示例

代码示例来源：origin: com.vaadin/flow-server

/**
 * Navigates forward. This has the same effect as if the user would press
 * the forward button in the browser. This causes a
 * {@link HistoryStateChangeEvent} to be fired asynchronously if the
 * conditions described in the <a href=
 * "https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onpopstate">
 * onpopstate documentation</a> are met.
 */
public void forward() {
  ui.getPage().executeJavaScript("history.forward()");
}

代码示例来源：origin: com.vaadin/flow-data

private Locale findLocale() {
  Locale locale = null;
  if (UI.getCurrent() != null) {
    locale = UI.getCurrent().getLocale();
  }
  if (locale == null) {
    locale = Locale.getDefault();
  }
  return locale;
}

代码示例来源：origin: com.vaadin/flow-server

/**
 * Called by the framework to remove an UI instance from the session because
 * it has been closed.
 *
 * @param ui
 *         the UI to remove
 */
public void removeUI(UI ui) {
  checkHasLock();
  assert UI.getCurrent() != null : "Current UI cannot be null";
  assert ui != null : "Removed UI cannot be null";
  assert UI.getCurrent().getUIId() == ui.getUIId() : "UIs don't match";
  ui.getInternals().setSession(null);
  uIs.remove(ui.getUIId());
}

代码示例来源：origin: com.vaadin/vaadin-spring

BeanStore getBeanStore(UI ui) {
  BeanStore beanStore = uiStores.get(ui.getUIId());
  if (beanStore == null) {
    beanStore = new BeanStore(session);
    uiStores.put(ui.getUIId(), beanStore);
    ui.addDetachListener(this);
  }
  return beanStore;
}

代码示例来源：origin: org.rapidpm.vaadin/rapidpm-vaadin-cdi-m-impl

@Override
protected ContextualStorage newContextualStorage(Integer uiId) {
  UI.getCurrent().addDetachListener(this::destroy);
  return super.newContextualStorage(uiId);
}

代码示例来源：origin: com.vaadin/vaadin-context-menu-flow

private UI getCurrentUI() {
    UI ui = UI.getCurrent();
    if (ui == null) {
      throw new IllegalStateException("UI instance is not available. "
          + "It means that you are calling this method "
          + "out of a normal workflow where it's always implicitly set. "
          + "That may happen if you call the method from the custom thread without "
          + "'UI::access' or from tests without proper initialization.");
    }
    return ui;
  }
}

代码示例来源：origin: com.vaadin/vaadin-tabs-flow

@Override
protected void onAttach(AttachEvent attachEvent) {
  getElement().getNode().runWhenAttached(ui -> ui.beforeClientResponse(
      this,
      context -> ui.getPage().executeJavaScript(
          "$0.addEventListener('items-changed', "
              + "function(){ this.$server.updateSelectedTab(true); });",
          getElement())));
}

代码示例来源：origin: com.vaadin/vaadin-cdi

public ContextualStorage getContextualStorage(boolean createIfNotExist) {
  final Integer uiId = UI.getCurrent().getUIId();
  return super.getContextualStorage(uiId, createIfNotExist);
}

代码示例来源：origin: com.vaadin/flow-server

private void queueBeforeExecutionCallback() {
  if (lifecycleOwner == null || !lifecycleOwner.getUI().isPresent()) {
    return;
  }
  if (executionRegistration != null) {
    executionRegistration.remove();
  }
  executionRegistration = lifecycleOwner.getUI().get()
      .beforeClientResponse(lifecycleOwner,
          beforeClientResponseConsumer);
}

代码示例来源：origin: com.vaadin/vaadin-context-menu-flow

ui -> ui.beforeClientResponse(this, context -> ui.getPage()
    .executeJavaScript("$0.listenOn=$1", this, target)));
ui -> ui.beforeClientResponse(target, context -> {
  ui.getInternals()
      .addComponentDependencies(ContextMenuBase.class);
  ui.getPage().executeJavaScript(
      "window.Vaadin.Flow.contextMenuConnector.init($0)",
      target.getElement());

代码示例来源：origin: com.vaadin/vaadin-notification-flow

/**
 * Opens or closes the notification.
 * <p>
 * Note: You don't need to add the component anywhere before opening it.
 * Since {@code <vaadin-notification>}'s location in the DOM doesn't really
 * matter, opening a notification will automatically add it to the
 * {@code <body>} if it's not yet attached anywhere.
 *
 * @param opened
 *            {@code true} to open the notification, {@code false} to close
 *            it
 */
@Override
public void setOpened(boolean opened) {
  UI ui = UI.getCurrent();
  if (ui == null) {
    throw new IllegalStateException("UI instance is not available. "
        + "It means that you are calling this method "
        + "out of a normal workflow where it's always implicitely set. "
        + "That may happen if you call the method from the custom thread without "
        + "'UI::access' or from tests without proper initialization.");
  }
  if (opened && getElement().getNode().getParent() == null) {
    ui.beforeClientResponse(ui, context -> {
      ui.add(this);
      autoAddedToTheUi = true;
    });
  }
  super.setOpened(opened);
}

代码示例来源：origin: com.vaadin/vaadin-text-field-flow

private static void execJS(Component component, String js) {
  StateNode node = component.getElement().getNode();
  node.runWhenAttached(ui -> ui.getInternals().getStateTree()
      .beforeClientResponse(node, context -> ui.getPage()
          .executeJavaScript(js, component.getElement())));
}

代码示例来源：origin: appreciated/vaadin-app-layout

public String getRoute() {
  if (className != null) {
    return UI.getCurrent().getRouter().getUrl(className);
  } else if (view != null) {
    return UI.getCurrent().getRouter().getUrl(view.getClass());
  } else {
    return getCaption();
  }
}

代码示例来源：origin: com.vaadin/flow-server

private static AtmospherePushConnection getConnectionForUI(UI ui) {
  PushConnection pushConnection = ui.getInternals().getPushConnection();
  if (pushConnection instanceof AtmospherePushConnection) {
    return (AtmospherePushConnection) pushConnection;
  } else {
    return null;
  }
}

代码示例来源：origin: com.vaadin/vaadin-cdi

private void destroy(DetachEvent event) {
    final int uiId = event.getUI().getUIId();
    super.destroy(uiId);
  }
}

代码示例来源：origin: com.vaadin/vaadin-confirm-dialog-flow

private void ensureAttached() {
    if (getElement().getNode().getParent() == null) {
      UI ui = getCurrentUI();
      ui.beforeClientResponse(ui, context -> {
        ui.add(this);
        autoAddedToTheUi = true;
      });
    }
  }
}

代码示例来源：origin: com.vaadin/flow-server

JsonObject response = Json.createObject();
UIInternals uiInternals = ui.getInternals();
VaadinSession session = ui.getSession();
VaadinService service = session.getService();
    nextClientToServerMessageId);
SystemMessages messages = ui.getSession().getService()
    .getSystemMessages(ui.getLocale(), null);
      encodeExecuteJavaScriptList(executeJavaScriptList));
if (ui.getSession().getService().getDeploymentConfiguration()
    .isRequestTiming()) {
  response.put("timings", createPerformanceData(ui));

代码示例来源：origin: com.vaadin/flow-server

/**
 * Closes those UIs in the given session for which {@link #isUIActive}
 * yields false.
 */
private void closeInactiveUIs(VaadinSession session) {
  final String sessionId = session.getSession().getId();
  for (final UI ui : session.getUIs()) {
    if (!isUIActive(ui) && !ui.isClosing()) {
      ui.accessSynchronously(() -> {
        getLogger().debug("Closing inactive UI #{} in session {}",
            ui.getUIId(), sessionId);
        ui.close();
      });
    }
  }
}

代码示例来源：origin: com.vaadin/flow-server

/**
 * Removes those UIs from the given session for which {@link UI#isClosing()
 * isClosing} yields true.
 *
 * @param session
 */
private void removeClosedUIs(final VaadinSession session) {
  List<UI> uis = new ArrayList<>(session.getUIs());
  for (final UI ui : uis) {
    if (ui.isClosing()) {
      ui.accessSynchronously(() -> {
        getLogger().debug("Removing closed UI {}", ui.getUIId());
        session.removeUI(ui);
      });
    }
  }
}

代码示例来源：origin: vaadin/spring

@Override
public void run() {
  // We can acquire the lock after the request started this thread is processed
  // Needed to make sure that this is sent as a push message
  Lock lockInstance = ui.getSession().getLockInstance();
  lockInstance.lock();
  lockInstance.unlock();
  ui.access(() -> execute(ui));
}