我有一个带有表单的menu.xhtml和一个ui：repeat来创建一个导航栏。但不知怎的，它没有显示任何数据。
名为menu.xhtml：
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets">
<h:head>
<title>Kitchen Memories</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css"></link>
</h:head>
<h:body>
<h4>Begin</h4>
<h:form>
<ui:repeat value="#{menuController.items}" var="item">
<h:commandButton value="#{item.name}"
action="#{menuController.setActive(item)}"
style="margin-bottom: 5px;"
immediate="true"
styleClass="#{item.active == true ? 'btn btn-primary' : 'btn btn-default'}"
/>
<br/>
</ui:repeat>
</h:form>
<h4>END</h4>
</h:body>
</html>
<h4>开始和结束是可见的。其余的没有。
我的MenuController.java：
@Named
@SessionScoped
public class MenuController implements Serializable
{
private List<Menu> items;
public MenuController()
{
}
public void init()
{
items = new LinkedList<>();
items.add(new Menu("Rezept finden", "findRecipe.xhtml", false));
items.add(new Menu("Rezepte verwalten", "manageRecipe.xhtml", false));
items.add(new Menu("Zutaten verwalten", "manageIngredient.xhtml", false));
System.out.println("MenuController aufgerufen.");
}
public String setActive(Menu item)
{
System.out.println("Call: setActive");
setAllInactive();
item.setActive(true);
return item.getUrl();
}
private void setAllInactive()
{
System.out.println("Call: setAllInactive()");
for(int i = 0; i < items.size(); i++)
{
items.get(i).setActive(false);
}
}
public List<Menu> getItems() {
System.out.println("Call getItems");
return items;
}
public void setItems(List<Menu> items) {
this.items = items;
}
}
我的Menu.java
public class Menu {
private String name;
private String url;
private boolean active;
public Menu(String name, String url, boolean active) {
this.name = name;
this.url = url;
this.active = active;
}
public boolean isActive() {
return active;
}
public void setActive(boolean active) {
this.active = active;
}
public Menu() {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
}
当我清理并构建项目时，我得到一个NullPointerException，但我不知道从哪里以及为什么我得到它。
Information: Session event listener threw exception
java.lang.NullPointerException
at org.jboss.weld.servlet.WeldTerminalListener.getSessionContext(WeldTerminalListener.java:72)
at org.jboss.weld.servlet.WeldTerminalListener.sessionDestroyed(WeldTerminalListener.java:64)
at org.apache.catalina.session.StandardSession.expire(StandardSession.java:910)
at org.apache.catalina.session.StandardSession.expire(StandardSession.java:854)
at org.apache.catalina.session.StandardSession.expire(StandardSession.java:842)
at org.apache.catalina.session.StandardManager.stop(StandardManager.java:955)
at org.apache.catalina.core.StandardContext.stop(StandardContext.java:6164)
at com.sun.enterprise.web.WebModule.stop(WebModule.java:720)
at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:1172)
at com.sun.enterprise.web.WebContainer.unloadWebModule(WebContainer.java:2439)
at com.sun.enterprise.web.WebContainer.unloadWebModule(WebContainer.java:2394)
at com.sun.enterprise.web.WebApplication.stop(WebApplication.java:190)
at org.glassfish.internal.data.EngineRef.stop(EngineRef.java:161)
at org.glassfish.internal.data.ModuleInfo.stop(ModuleInfo.java:324)
at org.glassfish.internal.data.ApplicationInfo.stop(ApplicationInfo.java:380)
at com.sun.enterprise.v3.server.ApplicationLifecycle.unload(ApplicationLifecycle.java:1059)
at com.sun.enterprise.v3.server.ApplicationLifecycle.undeploy(ApplicationLifecycle.java:1099)
at org.glassfish.deployment.admin.UndeployCommand.execute(UndeployCommand.java:412)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$2$1.run(CommandRunnerImpl.java:539)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$2$1.run(CommandRunnerImpl.java:535)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:360)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$2.execute(CommandRunnerImpl.java:534)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$3.run(CommandRunnerImpl.java:565)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$3.run(CommandRunnerImpl.java:557)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:360)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:556)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1464)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$1300(CommandRunnerImpl.java:109)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1846)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1722)
at com.sun.enterprise.v3.admin.AdminAdapter.doCommand(AdminAdapter.java:534)
at com.sun.enterprise.v3.admin.AdminAdapter.onMissingResource(AdminAdapter.java:224)
at org.glassfish.grizzly.http.server.StaticHttpHandlerBase.service(StaticHttpHandlerBase.java:189)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:206)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:180)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:283)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:200)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:132)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:111)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:536)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:591)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:571)
at java.lang.Thread.run(Thread.java:745)
我真的不知道为什么它没有显示任何东西。