我正在尝试使用内容-配置将某些内容从服务器保存到客户端计算机.当我单击jsp中的按钮时,对话框打开,我选择保存文件.文件已保存,但出现此异常.我已经读过其他类似的主题,例如“在某处,您的应用程序多次调用getOutputStream或getWriter”.但我不知道/不知道在哪里？

@Controller
public class ExportPhonebook2 {

    @Autowired
    private PhoneBookService phoneBookSer;

    private void setResponseHeader(HttpServletResponse response,String imenikTXT,File file){
    response.setHeader("Content-Length","" + file.length());
    response.setContentType("application/txt; charset=UTF-8");
    response.setHeader("content-disposition","attachement; filename=imenik.txt" );
    response.setHeader("Content-Transfer-Encoding","binary");
    } 

    @RequestMapping(value = "/exportPhonebook.html",method = RequestMethod.POST)
    public String exportPhonebook(Model model,HttpServletResponse response) {

        List<User> listOfAllUsers = phoneBookSer.fetchAllUsers();
        String imenik = "";

        for (User user : listOfAllUsers) {
            imenik = imenik + user.getPrezime() + " " + user.getIme() + ",Telefon: " + user.getTelefon() + ";\r\n" ;
        }


        try {

            File file = new File("c:\\imenik.txt");
            setResponseHeader(response,"imenik.txt",file);
            FileInputStream fileIn;
            fileIn = new FileInputStream(file);

            OutputStream outTXT = response.getOutputStream();

            byte[] outputByte = new byte[8192];
            //copy binary contect to output stream
            while(fileIn.read(outputByte,8192) != -1){
                outTXT.write(outputByte,8192);
            }
            fileIn.close();
            outTXT.flush();
            outTXT.close();
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
    } catch (IOException e) {
               // TODO Auto-generated catch block
                e.printStackTrace();
    }

            return "homepage";
    }
}

堆栈跟踪：

Exception initializing page context
java.lang.IllegalStateException: Cannot create a session after the response has been   committed
at org.apache.catalina.connector.Request.doGetSession(Request.java:2705)
at org.apache.catalina.connector.Request.getSession(Request.java:2231)
at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:899)
at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:229)
at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:572)
at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:517)
at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:238)
at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:238)
at org.apache.jasper.runtime.PageContextImpl._initialize(PageContextImpl.java:146)
at org.apache.jasper.runtime.PageContextImpl.initialize(PageContextImpl.java:125)
at org.apache.jasper.runtime.JspFactoryImpl.internalGetPageContext(JspFactoryImpl.java:112)
at org.apache.jasper.runtime.JspFactoryImpl.getPageContext(JspFactoryImpl.java:65)
at org.apache.jsp.WEB_002dINF.jsp.homepage_jsp._jspService(homepage_jsp.java:58)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:593)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:530)
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:229)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:328)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:116)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:95)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:79)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:119)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.authentication.logout.logoutFilter.doFilter(logoutFilter.java:105)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:175)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)