当前配置

Question

我们目前正在基于Vaadin Flow入门包开发一个新的Vaadin Web应用程序。它与码头服务器一起运行，该码头服务器通过maven调用启动。最近，经常弹出一个错误，阻止我访问浏览器中的应用程序，从而导致异常堆栈跟踪（在浏览器和后端）com.vaadin.flow.server.VaadinSession cannot be cast to com.vaadin.flow.server.VaadinSession。这是完整的堆栈跟踪。

javax.servlet.ServletException: javax.servlet.ServletException: com.vaadin.flow.server.ServiceException: java.lang.ClassCastException: com.vaadin.flow.server.VaadinSession cannot be cast to com.vaadin.flow.server.VaadinSession
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
    at org.eclipse.jetty.server.Server.handle(Server.java:531)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:352)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:260)
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:281)
    at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:102)
    at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:118)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:333)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:310)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:168)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:126)
    at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:366)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:762)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:680)
    at java.lang.Thread.run(Thread.java:748)
Caused by: javax.servlet.ServletException: com.vaadin.flow.server.ServiceException: java.lang.ClassCastException: com.vaadin.flow.server.VaadinSession cannot be cast to com.vaadin.flow.server.VaadinSession
    at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:302)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:857)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:535)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:146)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:257)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1317)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1219)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:219)
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:126)
    ... 15 more
Caused by: com.vaadin.flow.server.ServiceException: java.lang.ClassCastException: com.vaadin.flow.server.VaadinSession cannot be cast to com.vaadin.flow.server.VaadinSession
    at com.vaadin.flow.server.VaadinService.handleExceptionDuringRequest(VaadinService.java:1535)
    at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1498)
    at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:300)
    ... 33 more
Caused by: java.lang.ClassCastException: com.vaadin.flow.server.VaadinSession cannot be cast to com.vaadin.flow.server.VaadinSession
    at com.vaadin.flow.server.VaadinService.readFromHttpSession(VaadinService.java:2071)
    at com.vaadin.flow.server.VaadinService.loadSession(VaadinService.java:2051)
    at com.vaadin.flow.server.VaadinService.getExistingSession(VaadinService.java:942)
    at com.vaadin.flow.server.VaadinService.doFindOrCreateVaadinSession(VaadinService.java:791)
    at com.vaadin.flow.server.VaadinService.findOrCreateVaadinSession(VaadinService.java:766)
    at com.vaadin.flow.server.VaadinService.findVaadinSession(VaadinService.java:624)
    at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1480)
    ... 34 more

现在stacktrace本身就是其中一种，我之前从未见过类似的东西，因为它说它无法将VaadinSession强制转换为VaadinSession，这是不幸的。我很确定这些东西是由Vaadin本身处理的，我只是将其用作黑匣子，所以现在我真的不知道这些错误来自何处以及如何解决。

我正在扩展VaadinServlet以便连接到servlet和会话初始化，但是代码非常简单（尽管我不得不说我不是会话初始化方面的高手，所以我只是将其从其他教程中删除了）。我不确定这是否与它有关，反正就是下面的代码。

@Override
protected void servletInitialized() throws ServletException {
    super.servletInitialized();
    getService().addSessionInitListener(this);
    getService().addSessionDestroyListener(this);
    logger.info("servlet initialized");
}

@Override
public void sessionInit(SessionInitEvent event) throws ServiceException {
    // Do session start stuff here
    logger.info("session initialized");
    SessionBean sessionBean = new SessionBean();
    sessionBean.setPlant(Config.getInstance().getPlant());
    // TODO Berechtigungen aus dem Nutzer auslesen
    sessionBean.setAuthorizations(AUTHS);
    event.getSession().setAttribute(SessionBean.class, sessionBean);
    event.getSession().setAttribute(BPService.class, new BPService());
}

@Override
public void sessionDestroy(SessionDestroyEvent event) {
    event.getSession().setAttribute(SessionBean.class, null);
    event.getSession().setAttribute(BPService.class, null);
}

该错误在热部署以及全新启动时发生。重新启动应用程序服务器不一定能解决问题。一旦页面调用中出现错误（与哪个浏览器无关，我在Chrome，Opera，Firefox和IE中都出现了这些错误），如果我刷新此特定页面或尝试通过同一浏览器的新窗口。如果我切换到隐身窗口或切换浏览器，它将不会在新窗口中出现，但仍会在旧窗口中弹出。

当前配置

Vaadin 12.0.0（也发生在11.0.2中）
mvn jetty:run，码头有9.4.11.v20180605
java 1.8

我认为我目前正在使用Vaadin Flow的全部内容，我不确定它如何处理依赖关系，但这是我目前对Vaadin的唯一依赖：

<dependency>
    <groupId>com.vaadin</groupId>
    <artifactId>vaadin-bom</artifactId>
    <version>${vaadin.version}</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>

我尝试将码头服务器切换到其他版本，但没有成功。将Vaadin从11更新为12对该错误也没有影响。

应用程序调用时出现Vaadin流异常-VaadinSession无法转换为VaadinSession

当前配置

0 个答案: