java - Vaadin：TextField.getValue() 不返回在 CustomLayout 中输入的文本

Question

在我的 Vaadin 应用程序中，我有一个CustomLayout带有文本字段的面板：

public class BookkeepingView extends VerticalLayout implements View {

    private TextField userName;
    private PasswordField password;

    public BookkeepingView()
    {
        VerticalLayout contentPanel = new VerticalLayout();

        contentPanel.setStyleName("body");

        contentPanel.addComponent(getHeaderPanel());
        contentPanel.addComponent(getLoginPanel());
        contentPanel.addComponent(getFooterPanel());

        addComponent(contentPanel);
    }

    [...]

    private CustomLayout getLoginPanel() {
        Panel panel = new Panel();
        panel.setSizeUndefined();
        addComponent(panel);

        CustomLayout customLayoutPanel = new CustomLayout("login");

        userName = new TextField();
        userName.setImmediate(true);
        customLayoutPanel.addComponent(userName, "j_username");

当我在文本字段中输入文本时userName，按下带有如下所示事件处理程序的按钮，我得到一个空的用户名（托盘通知包含文本User name:）。

private void loginButtonPressed() {
    String userName = this.userName.getValue();
    Notification.show("User name:" + userName, Notification.Type.TRAY_NOTIFICATION);
}

如何修改代码，以便我可以从 a 中的userName文本字段中读取用户输入的值CustomLayout（我需要CustomLayout以便轻松自定义应用程序的外观）？

更新 1 (06.11.2013 18:16 MSK):

import com.vaadin.navigator.View;
import com.vaadin.navigator.ViewChangeListener;
import com.vaadin.ui.*;

public class BookkeepingView extends VerticalLayout implements View {

    private TextField userName;
    private PasswordField password;

    public BookkeepingView()
    {
        VerticalLayout contentPanel = new VerticalLayout();

        contentPanel.setStyleName("body");


        contentPanel.addComponent(getHeaderPanel());
        contentPanel.addComponent(getLoginPanel());
        contentPanel.addComponent(getFooterPanel());

        addComponent(contentPanel);
    }

    private Component getHeaderPanel() {
        return createCustomLayoutPanel("main-navigation");
    }

    private Component getFooterPanel() {
        return createCustomLayoutPanel("copyright");
    }

    private CustomLayout getLoginPanel() {
        Panel panel = new Panel();
        panel.setSizeUndefined();
        addComponent(panel);

        CustomLayout customLayoutPanel = new CustomLayout("login");

        userName = new TextField();
        userName.setImmediate(true);
        customLayoutPanel.addComponent(userName, "j_username");

        password = new PasswordField();
        customLayoutPanel.addComponent(password, "j_password");

        final Button loginButton = new Button(I18n.l("bookkeeping_login_button"));
        customLayoutPanel.addComponent(loginButton, "login");

        loginButton.addClickListener(new Button.ClickListener() {
            @Override
            public void buttonClick(Button.ClickEvent clickEvent) {
                loginButtonPressed();
            }
        });

        return customLayoutPanel;
    }

    private void loginButtonPressed() {
        String userName = this.userName.getValue();
        Notification.show("User name:" + userName, Notification.Type.TRAY_NOTIFICATION);
    }

    private CustomLayout createCustomLayoutPanel(final String aHtmlFileName) {
        Panel panel = new Panel();
        panel.setSizeUndefined();
        addComponent(panel);

        CustomLayout customLayoutPanel = new CustomLayout(aHtmlFileName);
        return customLayoutPanel;
    }


    @Override
    public void enter(ViewChangeListener.ViewChangeEvent event) {

    }
}