2011-1-22 15:18:23 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet action threw exception
java.lang.IllegalStateException: Cannot forward after response has been committed
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:312)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
    at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
    at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at loginfilter.LoginFilter.doFilter(LoginFilter.java:55)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:619)

    <form action="/NMSoftware/admission.do?method=queryExcel"
            method="post">
            
<input type="hidden" value="20" name="pagesize" />
<input type="hidden" value="1" name="pagenow" />
<input type="submit" value="导出Excel" />
            
        </form>

public ActionForward queryExcel(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response){
        try {
        HttpSession session = request.getSession();
        String spagenow = request.getParameter("pagenow");
        String spagesize = request.getParameter("pagesize");
        int pagenow = Integer.parseInt(spagenow);
        int pagesize = Integer.parseInt(spagesize);
        SqlBean sq = new SqlBean();
        List list = null;
        String tt = "";
        if (session.getAttribute("stockgoods") != null) {
            List sessionList = (List) session.getAttribute("stockgoods");

            for (int i = 0; i < sessionList.size(); i++) {
                AddQueryForm af = (AddQueryForm) sessionList.get(i);

                tt += af.getFieldnamel() + " " + af.getOperator() + " '"
                        + af.getFieldvalues() + "' " + af.getManner() + " ";

            }
            list = sq.accnsQuery(pagesize, pagenow, tt);

        } else {
            list = sq.accnsQuery(pagesize, pagenow, null);
        }
        String str = "学生登记信息表";
        String sstr = new String(str.getBytes("gb2312"), "ISO-8859-1");
        
            OutputStream os = response.getOutputStream();// 取得输出流
            response.reset();// 清空输出流
            response.setHeader("Content-disposition", "attachment; filename="
                    + sstr + ".xls");// 设定输出文件头
            response.setContentType("application/msexcel");// 定义输出类型
            response.setCharacterEncoding("gb2312");
            WritableWorkbook wbook = Workbook.createWorkbook(os); // 建立excel文件
            WritableSheet wsheet = wbook.createSheet("sheet1", 0); // sheet名称

            // 设置excel标题
            WritableFont wfont = new WritableFont(WritableFont.ARIAL, 16,
                    WritableFont.BOLD, false, UnderlineStyle.NO_UNDERLINE);
            WritableCellFormat wcfFC = new WritableCellFormat(wfont);
            wcfFC.setAlignment(Alignment.CENTRE);

            // 开始生成主体内容
            wsheet.addCell(new Label(0, 0, "编号"));
            wsheet.addCell(new Label(1, 0, "姓名"));
            wsheet.addCell(new Label(2, 0, "拼音码"));
            wsheet.addCell(new Label(3, 0, "性别"));
            wsheet.addCell(new Label(4, 0, "申请日期"));
            wsheet.addCell(new Label(5, 0, "入托方式"));
            wsheet.addCell(new Label(6, 0, "班级"));
            wsheet.addCell(new Label(7, 0, "接送方式"));
            wsheet.addCell(new Label(8, 0, "特长班"));

            int i = 1, j = 1;
            for (int n = 0; n < list.size(); n++) {
                Adms_Car_Class_Nur_SpeForm ssf = (Adms_Car_Class_Nur_SpeForm) list
                        .get(n);
                wsheet.addCell(new Label(0, i, j + ""));
                wsheet.addCell(new Label(1, i, ssf.getAdname()));
                wsheet.addCell(new Label(2, i, ssf.getAdcode()));
                wsheet.addCell(new Label(3, i, ssf.getAdsex()));
                wsheet.addCell(new Label(4, i, ssf.getAdtime()));
                wsheet.addCell(new Label(5, i, ssf.getNursery()));
                wsheet.addCell(new Label(6, i, ssf.getClassname()));
                wsheet.addCell(new Label(7, i, ssf.getCarname()));
                wsheet.addCell(new Label(8, i, ssf.getSpecialtyname()));
                i++;
                j++;
            }

            // 主体内容生成结束
            wbook.write(); // 写入文件
            wbook.close();
            os.flush();
            os.close(); // 关闭流
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return mapping.getInputForward();
    }