我正在将Spring整合到Vaadin中，感谢Vaadin Spring插件和这个wiki：https://vaadin.com/wiki?p_p_id=36&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&p_p_col_id=row-1&p_p_col_pos=2&p_p_col_count=4&_36_struts_action=%2Fwiki%2Fview&p_r_p_185834411_nodeName=vaadin.com+wiki&p_r_p_185834411_title=I+-+Getting+started+with+Vaadin+Spring我实际上能够做到。
然而，当我重新启动Tomcat并重新启动Vaadin应用程序时，我得到以下NotSerializableException抱怨Spring的XmlWebApplicationContext：
SEVERE: Exception loading sessions from persistent storage
java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: org.springframework.web.context.support.XmlWebApplicationContext
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1355)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
at java.util.LinkedList.readObject(LinkedList.java:1149)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1896)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:501)
at com.vaadin.server.VaadinSession.readObject(VaadinSession.java:1443)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1896)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
at org.apache.catalina.session.StandardSession.doReadObject(StandardSession.java:1634)
at org.apache.catalina.session.StandardSession.readObjectData(StandardSession.java:1099)
at org.apache.catalina.session.StandardManager.doLoad(StandardManager.java:261)
at org.apache.catalina.session.StandardManager.load(StandardManager.java:180)
at org.apache.catalina.session.StandardManager.startInternal(StandardManager.java:460)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5213)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1399)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.NotSerializableException: org.springframework.web.context.support.XmlWebApplicationContext
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at java.util.LinkedList.writeObject(LinkedList.java:1131)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at org.apache.catalina.session.StandardSession.doWriteObject(StandardSession.java:1710)
at org.apache.catalina.session.StandardSession.writeObjectData(StandardSession.java:1116)
at org.apache.catalina.session.StandardManager.doUnload(StandardManager.java:401)
at org.apache.catalina.session.StandardManager.unload(StandardManager.java:320)
at org.apache.catalina.session.StandardManager.stopInternal(StandardManager.java:487)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5409)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
at org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1425)
at org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1414)
... 4 more
实际上代码非常简单（基于教程和其他一些Spring功能）：
这是UI类：
package com.example.vaadinwithspring;
//...
@SpringUI("")
@Theme("valo")
@SuppressWarnings("serial")
public class MyUI extends UI {
private transient ApplicationContext appContext;
@Override
protected void init(VaadinRequest vaadinRequest) {
final VerticalLayout layout = new VerticalLayout();
layout.setMargin(true);
setContent(layout);
UserService service = getUserService(vaadinRequest);
User user = service.getUser();
String userName = user.getName();
Label userHelloLabel = new Label("Hello " + userName + "!");
layout.addComponent(userHelloLabel);
}
@WebListener
public static class MyContextLoaderListener extends ContextLoaderListener {
}
@Configuration
@EnableVaadin
public static class MyConfiguration {
@Bean(name="userService")
public UserService helloWorld() {
return new UserServiceImpl();
}
}
@WebServlet(urlPatterns = "/*", name = "MyUIServlet", asyncSupported = true)
@VaadinServletConfiguration(ui = MyUI.class, productionMode = false)
public static class MyUIServlet extends SpringAwareVaadinServlet {
}
private UserService getUserService(VaadinRequest request) {
WrappedSession session = request.getWrappedSession();
HttpSession httpSession = ((WrappedHttpSession) session).getHttpSession();
ServletContext servletContext = httpSession.getServletContext();
appContext = WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);
return (UserService) appContext.getBean("userService");
}
}
虽然非常混乱（我遵循了wiki），但这里唯一重要的事情是Vaadin Spring注释（@SpringUI("")，@EnableVaadin，如链接教程）和一些Spring的注释（除了@Configuration之外，我还通过@Bean类中的MyConfiguration注释定义了一个名为“userService”的 Spring bean 。还请注意，我有一个成员 transient 字段，它引用了Spring的ApplicationContext（我在UI的getUserService（VaadinRequest）方法中使用它以获取“userService”bean）。
以下是UserService界面和课程UserServiceImpl的代码：
package com.example.vaadinwithspring;
public class UserService {
public User getUser();
}
-------------------------------------------------------------------
package com.example.vaadinwithspring;
public class UserServiceImpl implements UserService {
@Override
public User getUser() {
User user = new User();
user.setName("UserName");
return user;
}
}
然后，User类：
package com.example.vaadinwithspring;
public class User {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
所有组件都是虚拟实现，只是为了看到Vaadin与Spring合作并且一切正常。
最后， Vaadin Spring 教程建议使用applicationContext.xml并在不使用Spring Boot or JavaConfig时将其放在src / main / webapp / WEB-INF /中。
我创建了以下applicationContext.xml：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.1.xsd">
<bean class="com.example.vaadinwithspring.MyUI.MyConfiguration" />
<context:component-scan base-package="com.example.vaadinwithspring" />
</beans>
现在，正如我所说，如果我启动应用程序，一切都很有效。我遇到的唯一问题是，当我重新启动应用程序时NotSerializableException与XmlWebApplicationContext相关。
如果我有一个不应序列化的瞬态ApplicationContext成员，为什么会抛出异常呢？我想Spring使用XmlWebApplicationContext的另一个实例并在内部使用它，是这样吗？然后：
有没有办法解决它？怎么样？
感谢您的关注！
答案 0 :(得分：3)
默认情况下，Tomcat尝试在重新启动时加载上一次运行的会话。如果加载那些会话（您的情况）失败，它会将错误打印到日志，然后正常初始化您的应用程序。实际上，这里没有问题，但是你没有得到会话持久性。除非您使用的是生产应用，否则您不需要此功能。
除了忽略它之外，您可以采取一些方法：
我认为问题来自SpringAwareVaadinServlet。它将applicationContext注入SpringAwareUIProvider，并有效地存储在持久会话存储中。
如果你真的想要使用此设置进行会话持久性，则需要扩展VaadinServlet并实现一个不存储UIProvider本身的自定义applicationContext，但它可以从其他地方获取，可能servlet中的静态字段。