??? 在Spring2.0中除了以前的Singleton和Prototype外又加入了三個新的web作用域，分別為
request、session和global session，它們的含義和用法請大家參考Spring官方手冊的相關章節。如果你想讓你的容器里的某個bean擁有其中某種新的web作用域，除了在bean級上配置相應的scope屬性
，還必須在容器級做一個額外的初始化配置。即在web應用的XML聲明文件
web.xml中增加下述
ContextListener：
1?
<web-app>
2?
??
3?
??<listener>
4?
????<listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
5?
??</listener>
6?
??
7?
</web-app>
??? 如果你用的是早期版本的web容器（Servlet 2.4以前），那么你要使用一個javax.servlet.Filter的實現。
?1?
<web-app>
?2?
??..
?3?
??<filter>?
?4?
????<filter-name>requestContextFilter</filter-name>?
?5?
????<filter-class>org.springframework.web.filter.RequestContextFilter</filter-class>
?6?
??</filter>?
?7?
??<filter-mapping>?
?8?
????<filter-name>requestContextFilter</filter-name>?
?9?
????<url-pattern>/*</url-pattern>
10?
??</filter-mapping>
11?
??
12?
</web-app> ??? 兩種方式完成完全一樣的功能：基于LocalThread將HTTP request對象綁定到為該請求提供服務的線程上。這使得具有request和session作用域的bean能夠在后面的調用鏈中被訪問到。
??? 我一直使用的是Filter的配置方式，雖然使用的web容器Resin3.0.19是支持servlet2.4的但也懶得改為更為簡潔的Listener了。使用一切正常，昨日無聊翻閱Spring的手冊無意中又看到這一節，想想自己也太懶了，幾句話就改了為什么不更簡單呢？于是就把配置改成了Listener的方式，啟動一切正常，但當請求第一個鏈接時居然報錯了！
?1?java.lang.NullPointerException
?2?????at?org.springframework.web.context.request.RequestContextListener.requestDestroyed(RequestContextListener.java:67)
?3?????at?com.caucho.server.webapp.DispatchFilterChain.doFilter(DispatchFilterChain.java:120)
?4?????at?com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
?5?????at?com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:277)
?6?????at?com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:106)
?7?????at?org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
?8?????at?org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
?9?????at?org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
10?????at?org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
11?????at?org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
12?????at?javax.servlet.http.HttpServlet.service(HttpServlet.java:115)
13?????at?javax.servlet.http.HttpServlet.service(HttpServlet.java:92)
14?????at?com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:106)
15?????at?org.extremecomponents.table.filter.AbstractExportFilter.doFilter(AbstractExportFilter.java:49)
16?????at?com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
17?????at?org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:173)
18?????at?org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:77)
19?????at?com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
20?????at?org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:78)
21?????at?org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:77)
22?????at?com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
23?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:264)
24?????at?org.acegisecurity.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:107)
25?????at?org.acegisecurity.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:72)
26?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
27?????at?org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:110)
28?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
29?????at?org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
30?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
31?????at?org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142)
32?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
33?????at?org.acegisecurity.wrapper.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:81)
34?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
35?????at?org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:217)
36?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
37?????at?org.acegisecurity.ui.logout.LogoutFilter.doFilter(LogoutFilter.java:106)
38?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
39?????at?org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:229)
40?????at?org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:274)
41?????at?org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:148)
42?????at?org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:98)
43?????at?com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
44?????at?com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:178)
45?????at?com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
46?????at?com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:268)
47?????at?com.caucho.server.port.TcpConnection.run(TcpConnection.java:389)
48?????at?com.caucho.util.ThreadPool.runTasks(ThreadPool.java:507)
49?????at?com.caucho.util.ThreadPool.run(ThreadPool.java:433)
50?????at?java.lang.Thread.run(Thread.java:595)
51?[10:01:26.109]?java.lang.NullPointerException
52?[10:01:26.109]?????at?org.springframework.web.context.request.RequestContextListener.requestDestroyed(RequestContextListener.java:67)
53?[10:01:26.109]?????at?com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:188)
54?[10:01:26.109]?????at?com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
55?[10:01:26.109]?????at?com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:268)
56?[10:01:26.109]?????at?com.caucho.server.port.TcpConnection.run(TcpConnection.java:389)
57?[10:01:26.109]?????at?com.caucho.util.ThreadPool.runTasks(ThreadPool.java:507)
58?[10:01:26.109]?????at?com.caucho.util.ThreadPool.run(ThreadPool.java:433)
59?[10:01:26.109]?????at?java.lang.Thread.run(Thread.java:595)
??? 順便說一下，用Listenter方式配置初始化ApplicationContext的ContextLoaderListener是正常的，它也是需要servlet2.4支持的，所以應該不是因為容器支持的servlet版本問題。 ?
??? 換回Filter后一切正常，看了一下Spring源碼也沒看除個所以然，在網上找了很久也沒找到答案，很是郁悶！希望路過的高人們能夠不吝賜教，感激涕零！
posted on 2007-02-08 10:10
cresposhi 閱讀(5529)
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