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java无法在会话超时时获取会话范围的bean

2 月，3 周 Questions & Answers

我需要在HttpSessionListener.sessionDestroyed()上获得一个代理会话范围的bean。目标是在会话被破坏（通过invalidate()或超时）时进行会话清理。我添加了ContextLoaderListener来公开上下文，并通过WebApplicationContextUtils.getWebApplicationContext()获得了bean

如果我自己在Servlet中使会话无效，那么一切都可以正常工作，但是当会话超时时，我会得到一个Scope 'session' is not active for the current thread;。我知道清理工作是由Servlet引擎的内部线程完成的，但我仍然需要能够从HttpSessionListener获取这个bean

我周围似乎有很多相同的问题，没有人找到解决方案，这就是为什么我要再次提问

我的应用程序上下文。xml没有bean声明，因为我使用的是注释

这是会话超时时我需要访问的bean：

@Component
@Scope(value="session", proxyMode=ScopedProxyMode.TARGET_CLASS)
public class Access {

    static private int SERIAL = 0;
private int serial;

    public Access() {
            serial = SERIAL++;
    }

    public int getSerial() {
            return serial;
    }
}

这是create或destroy手动启动会话的控制器

@Controller
public class Handler {

    @Autowired
    Access access;


    @RequestMapping("/create")
    public @ResponseBody String create() {
        return "Created "+access.getSerial();
    }

    @RequestMapping("/destroy")
    public @ResponseBody String destroy(HttpSession sess) {
        int val = access.getSerial();
        sess.invalidate();
        return "Destroyed "+val;
    }

}

这是收听会话销毁的HttpSessionListener，在这里我需要访问Access会话范围bean的内容

public class SessionCleanup implements HttpSessionListener {

@Override
public void sessionDestroyed(HttpSessionEvent ev) {

    // Get context exposed at ContextLoaderListener
    WebApplicationContext ctx = WebApplicationContextUtils
        .getWebApplicationContext(ev.getSession().getServletContext());

    // Get the beans
    Access v = (Access) ctx.getBean("access");

    // prints a not-null object
    System.out.println(v);

    // this line raise the exception
    System.out.println(v.getSerial());

    }


    @Override
    public void sessionCreated(HttpSessionEvent ev) {/*Nothing to do*/}

}

下面的例外情况是在v.getSerial()提出的

Ago 14, 2012 11:44:58 PM org.apache.catalina.session.StandardSession expire
SEVERE: Session event listener threw exception
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.access': Scope 'session' is not active for the current thread; consider defining a scoped proxy for this bean if you intend to refer to it from a singleton; nested exception is java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:342)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:33)
    at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.getTarget(Cglib2AopProxy.java:654)
    at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:605)
    at model.Access$$EnhancerByCGLIB$$438f41a5.toString(<generated>)
    at java.lang.String.valueOf(String.java:2902)
    at java.io.PrintStream.println(PrintStream.java:821)
    at org.apache.tomcat.util.log.SystemLogHandler.println(SystemLogHandler.java:242)
    at service.SessionCleanup.sessionDestroyed(SessionCleanup.java:24)
    at org.apache.catalina.session.StandardSession.expire(StandardSession.java:709)
    at org.apache.catalina.session.StandardSession.isValid(StandardSession.java:576)
    at org.apache.catalina.session.ManagerBase.processExpires(ManagerBase.java:712)
    at org.apache.catalina.session.ManagerBase.backgroundProcess(ManagerBase.java:697)
    at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1364)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1649)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1658)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1658)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1638)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
    at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131)
    at org.springframework.web.context.request.SessionScope.get(SessionScope.java:90)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:328)
    ... 19 more

最后，这里是我的网站。xml

<?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">

  <display-name>session-listener-cleanup</display-name>


    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring-config.xml</param-value>
    </context-param>


    <listener>
      <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>

    <listener>
      <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>


    <listener>
      <listener-class>service.SessionCleanup</listener-class>
    </listener>


    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>


    <session-config>
      <session-timeout>1</session-timeout>
    </session-config>


</web-app>

正如我所说，当我在控制器的方法destroy中使会话无效时，一切都很顺利

更新1：找到可能的解决方案

出现这个问题是因为需要一个请求才能Spring访问会话bean。事件虽然我们有一个与线程关联的上下文，但没有请求

这里有一些可能的选择：

  1. 按照alexwen的建议，实现接口DisposableBean。这意味着将业务逻辑移动到模型对象 [here]
  2. 实施DestructionAwareBeanPostProcessor也由alexwen建议。这意味着在进行任何处理之前，您需要检查被处理的bean是否为Access
  3. 直接从会话中检索bean。这种方式不是很好，因为你使用了一种未记录的行为来实现结果，但确实有效 [here]
  4. 模拟servlet请求，并通过RequestContextHolder将其属性绑定到线程。这也会导致未记录的行为，在未来的版本中可能会被更改 [here]

我没有选择最后两个，因为它们没有记录。而且，我不喜欢在一颗特定的豆子之后清除每一颗豆子。由于我也不想将业务逻辑混合到我的模型bean中，所以我最终创建了一个@Service来创建bean，并且还有一个destroy方法

这个方法由访问bean的处理负责。我在Access上实现了DisposableBean接口，将AccessManager服务注入Accessbean，并调用服务destroy方法。服务如下所示：

@Service
public class AccessManager {

    @Bean(name="access", destroyMethod="destroy")
    @Scope(value="session", proxyMode=ScopedProxyMode.TARGET_CLASS)
    @Autowired
    public Access create(HttpServletRequest request) {
        // creation logic
    }


    public void destroy(Access access) {
        // disposal logic
    }

}

共 (1) 个答案