我正在使用Wicket 7,最近有以下例外:
org.apache.wicket.core.request.handler.ComponentNotFoundException:
Component 'navbar:navbarAvatar:navAvatarPanel:4:navAvatarArea:menuPanel:menuItem:menuLink' has been removed from page.
此错误来自我建造的顶级导航栏。导航栏具有一个子菜单(Navavatarpanel(,其中包含其他菜单链接(Menulink(。链接被添加到arrayList中,并使用片段在listView中显示。
这是我的代码:
navbarpanel.java
public class NavBarPanel extends Panel {
public NavBarPanel(String id) {
super(id);
/* ... */
WebMarkupContainer navBarAvatar = new WebMarkupContainer(NavbarAvatar$wicketId) {
private static final long serialVersionUID = -2447768280463773678L;
@Override
public boolean isVisible() {
return session.isSignedIn();
}
};
List<Panel> avatarMenuItems = new ArrayList<Panel>();
avatarMenuItems.add(new MenuLink(Logout$wicketId, "Logout", WelcomeWebPage.class, menuModel));
/* adding additional links at this point ... */
navBarAvatar.add(new ListView<Panel>("navAvatarPanel", avatarMenuItems) {
private static final long serialVersionUID = 1L;
@Override
protected void populateItem(ListItem<Panel> item) {
final Panel panel = item.getModelObject();
item.add(new MenuFragment(panel, "navAvatarArea"));
}
});
this.add(navBarAvatar);
}
}
public class MenuFragment extends Fragment {
private static final long serialVersionUID = 5735397386662232792L;
public MenuFragment(Panel panel, String area) {
super(area, "menuFragment", NavBarPanel.this);
add(panel);
}
}
navbarpanel.html
<wicket:panel>
<!-- ... -->
<div wicket:id="navbarAvatar" class="navbar-avatar">
<ul>
<wicket:container wicket:id="navAvatarPanel">
<wicket:container wicket:id="navAvatarArea"/>
</wicket:container>
</ul>
</div>
<!-- ... -->
<wicket:fragment wicket:id="menuFragment">
<wicket:container wicket:id="menuPanel"></wicket:container>
</wicket:fragment>
</wicket:panel>
menulink.java
public MenuLink(String markupId, String label, Class<? extends Page> page, MenuModel model) {
super("menuPanel");
this.markupId = markupId;
this.page = page;
this.model = model;
this.initComponentTree(label);
}
private void initComponentTree(final String label) {
WebMarkupContainer menuItem = new WebMarkupContainer("menuItem");
Link<Void> menuLink = new Link<Void>("menuLink") {
private static final long serialVersionUID = 1L;
@Override
public void onClick() {
MenuLink.this.menuOnClick(label);
}
};
menuLink.add(new Label("menuLabel", label));
menuLink.setMarkupId(this.markupId);
menuItem.add(menuLink);
this.add(menuItem);
}
menulink.html
<wicket:panel>
<li wicket:id="menuItem">
<a wicket:id="menuLink">
<span wicket:id="menuLabel">[label]</span>
</a>
</li>
</wicket:panel>
我不知道此错误来自何处。我也没有成功找到有关此例外的更多信息。
我的猜测是HTTP会话已经过期,并且无法找到菜单项,因为由于isVisible = session.isSignedIn();
不存在整个菜单。
如果是这种情况,则应改进检票口,以给出更好的例外消息,告知无法找到哪个组件,而不是所请求的组件路径。
P.S。建议使用onConfigure() {setVisible(...)}
而不是覆盖isVisible()
,因为后者在渲染过程中被称为几次,并且可能较慢。