我正在使用JSF2.2＆amp; Tomcat 6.0.35。 我有一个应用程序，我们显示＆amp;编辑用户详细信息 我发送ajax请求对每个输入的更改进行一些处理以获取编辑细节＆amp;更新表格。
当我在很长的空闲时间（30分钟后）尝试更改任何输入时， 我从Managed Bean实例变量获取NullPointerException。 服务器是否已经清理了很长时间闲置的实例，这是客户端浏览器不知道的？
这是代码。
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:c="http://java.sun.com/jsp/jstl/core"
xmlns:ui="http://java.sun.com/jsf/facelets">
<h:head>
<title> VSP </title>
<meta http-equiv="expires" content="0"/>
<meta http-equiv="pragma" content="no-cache"/>
<meta http-equiv="cache-control" content="no-cache"/>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<link rel="stylesheet" href="vsp.css" type="text/css" />
<script type="text/javascript">
//<![CDATA[
jQuery("#designForm :input[type='text']:enabled:not([readonly='readonly'])").live('change', function(){
var componentId = jQuery(this).attr("id");
validateInputData(componentId);
var validForm = (jQuery(".errorMsg").length == 0) ? true : false;
if(validForm){
jQuery("#submitDesignForm").click();
}
});
</script>
</h:head>
<h:body>
<div id="header">
<ui:insert name="commonHeader">
<ui:include src="header.xhtml" />
</ui:insert>
</div>
<div id="content">
<ui:insert name="commonBodyContent">
<h:form id="designForm" prependId="false" autocomplete="off">
Common Body Content.
<h:commandLink id="submitDesignForm" style="display:none;">
<f:ajax execute="@form"
render="@form"
listener="#{designBean.processDetails}"/>
</h:commandLink>
</h:form>
</ui:insert>
</div>
<div id="footer">
<ui:insert name="commonFooter">
<ui:include src="footer.xhtml" />
</ui:insert>
</div>
</h:body>
</html>
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets"
template="commonTemplate.xhtml">
<ui:define name="commonBodyContent">
<table>
<tr>
<td>Name</td>
<td>#{designBean.person.name}</td>
</tr>
<tr>
<td>Age</td>
<td>#{designBean.person.age}</td>
</tr>
<tr>
<td>Email</td>
<td>#{designBean.person.email}</td>
</tr>
<tr>
<td>Nationality</td>
<td>#{designBean.person.nation}</td>
</tr>
<tr>
<td>Date-Of-Birth</td>
<td>#{designBean.person.dob}</td>
</tr>
.........;
..........;
</table>
</ui:define>
</ui:composition>
editDetails.xhtml
------------------
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets"
template="commonTemplate.xhtml">
<ui:define name="commonBodyContent">
<table>
<tr>
<td>Name</td>
<td><h:inputText value="#{designBean.person.name}" /></td>
</tr>
<tr>
<td>Age</td>
<td><h:inputText value="#{designBean.person.age}" /></td>
</tr>
<tr>
<td>Email</td>
<td><h:inputText value="#{designBean.person.email}" disabled="true"/></td>
</tr>
<tr>
<td>Nationality</td>
<td><h:inputText value="#{designBean.person.nation}" /></td>
</tr>
<tr>
<td>Date-Of-Birth</td>
<td><h:inputText value="#{designBean.person.dob}" /></td>
</tr>
.........;
..........;
</table>
</ui:define>
</ui:composition>
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
id="WebApp_ID" version="2.5">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<context-param>
<param-name>javax.faces.FACELETS_SKIP_COMMENTS</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>client</param-value>
</context-param>
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.xhtml</param-value>
</context-param>
<context-param>
<param-name>javax.faces.SEPARATOR_CHAR</param-name>
<param-value>_</param-value>
</context-param>
<context-param>
<param-name>com.sun.faces.expressionFactory</param-name>
<param-value>org.jboss.el.ExpressionFactoryImpl</param-value>
</context-param>
<context-param>
<param-name>javax.faces.PROJECT_STAGE</param-name>
<param-value>Development</param-value>
</context-param>
<context-param>
<param-name>javax.faces.DATETIMECONVERTER_DEFAULT_TIMEZONE_IS_SYSTEM_TIMEZONE</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>com.sun.faces.disableUnicodeEscaping</param-name>
<param-value>true</param-value>
</context-param>
<filter>
<filter-name>characterEncodingFilter</filter-name>
<filter-class>org.omnifaces.filter.CharacterEncodingFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>noCacheFilter</filter-name>
<filter-class>org.omnifaces.filter.CacheControlFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>noCacheFilter</filter-name>
<servlet-name>facesServlet</servlet-name>
</filter-mapping>
<filter>
<filter-name>facesExceptionFilter</filter-name>
<filter-class>org.omnifaces.filter.FacesExceptionFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>facesExceptionFilter</filter-name>
<servlet-name>facesServlet</servlet-name>
</filter-mapping>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.faces</url-pattern>
</servlet-mapping>
<error-page>
<exception-type>javax.faces.application.ViewExpiredException</exception-type>
<location>/viewExpired.faces</location>
</error-page>
<error-page>
<exception-type>java.sql.SQLException</exception-type>
<location>/systemUnavailable.faces</location>
</error-page>
<error-page>
<exception-type>java.lang.RuntimeException</exception-type>
<location>/error.faces</location>
</error-page>
<error-page>
<error-code>500</error-code>
<location>/error.faces</location>
</error-page>
<error-page>
<error-code>403</error-code>
<location>/invalidAccess.faces</location>
</error-page>
<error-page>
<error-code>404</error-code>
<location>/notFound.faces</location>
</error-page>
<security-constraint>
<display-name>Restrict raw XHTML Documents</display-name>
<web-resource-collection>
<web-resource-name>XHTML</web-resource-name>
<url-pattern>*.xhtml</url-pattern>
</web-resource-collection>
<auth-constraint />
</security-constraint>
</web-app>
@ViewScoped
@ManagedBean(name="designBean")
public class DesignBean implements Serializable{
@ManagedProperty(value = "#{userBean}")
private UserBean userBean;
@ManagedProperty("#{userService}")
private UserService userService; // This is an application scoped managed bean with eager true.
private Person person;
@PostConstruct
public void initBean(){
System.out.println("DesignBean created!");
person = new Person();
String userEmail = userBean.getUserEmail();
if(userEmail!=null && !userEmail.isEmpty()){
person = userService.getUserDetails(userEmail);
}
}
public void processDetails(){
person.setLastUpdateTime(new Date()); // Getting NPE here, person object is null after long idle time.
userService.updateUser(person);
}
public void setUserBean(UserBean userBean) {
this.userBean = userBean;
}
public UserBean getUserBean() {
return userBean;
}
public void setUserService(UserService userService) {
this.userService = userService;
}
public UserService getUserService() {
return userService;
}
public void setPerson(Person person){
this.person = person;
}
public Person getPerson(){
return person;
}
}
public class Person implements Serializable {
private String name;
private Integer age;
private String email;
private String nation;
private String dob;
private Date lastUpdateTime;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getNation() {
return nation;
}
public void setNation(String nation) {
this.nation = nation;
}
public String getDob() {
return dob;
}
public void setDob(String dob) {
this.dob = dob;
}
public void setLastUpdateTime(Date lastUpdateTime){
this.lastUpdateTime = lastUpdateTime;
}
public Date getLastUpdateTime(){
return lastUpdateTime;
}
}