開發環境的伺服器是Tomcat，測試環境的伺服器是WebLogic。開發匯出功能選用元件POI，同時想在使用者匯出資料時同時彈出匯出框，讓使用者自由選擇下載位置。在Tomcat環境下匯出資料時沒有問題， WebLogic環境下測試發現匯出資料拋異常。
異常資訊： java.lang.IllegalStateException: strict servlet API: cannot call getWriter() after getOutputStream()
異常程式碼寫法如下：

//匯出
String fileName = new SimpleDateFormat("yyyyMMdd_HHmmss"
 
).format(new Date()) +".xls";
response.setContentType("application/vnd.ms-excel; charset=utf-8");
response.setHeader("Content-Disposition", "attachment;fileName="+fileName);
response.setCharacterEncoding("utf-8");
wb.write(response.getOutputStream());

追其原因，網上有說兩者不能同時使用，也有說是weblogic的問題

連線地址1
連線地址2

最終解決方案

/**
 * 匯出Excel
 */
@RequestMapping("/exportExcel")
public String exportExcel(HttpServletRequest request, HttpServletResponse response) throws Exception{

    //獲取查詢條件
    Map<String, Object> paramMap = this.getRequestParamMap(request);

    //定義表的標題
    String[] header = {"序號"
 
,"ID","姓名","性別","年齡","地址"};

    //定義表的內容
    List<Object[]> contentsList = service.getExportData(paramMap);

    //匯出Excel
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    try {
        Workbook wb = excelUtil.getWorkbook(header, contentsList);
        wb.write(os);
    } catch (Exception e) {
        e.printStackTrace();
    }

    byte[] content = os.toByteArray();
    InputStream is = new ByteArrayInputStream(content);

    //設定response引數，可以開啟下載頁面
    response.reset();
    response.setContentType("application/vnd.ms-excel; charset=utf-8") ;
    response.setHeader("Content-Disposition", "attachment; filename=" + excelUtil.getFileName());

    ServletOutputStream out = response.getOutputStream();
    BufferedInputStream bis = null;
    BufferedOutputStream bos = null;
    try {
        bis = new BufferedInputStream(is);
        bos = new BufferedOutputStream(out);

        byte[] buff = new byte[2048];
        int bytesRead;

        while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
            bos.write(buff, 0, bytesRead);
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (bis != null)
            bis.close();
        if (bos != null)
            bos.close();
    }

    return null;                            
}