需求描述：
需要將前端的某些資料生成Excel檔案，並提供下載功能。
解決方案：
前端通過ajax的方式將資料資訊傳到後臺，後臺使用POI元件動態生成Excel檔案流，並寫入資料資訊，返回前端供前端下載。
程式碼示例：

// 前端程式碼
$.ajax({
                    url: "/ExportExcelServer/SubmitExcelData",
                    type: "post",
                    dataType: "json",
                    data:paramData,
                    success: function
 
 (data) {
                        if (data&&data.code=="1") {
                             window.location.href = "/ExportExcelServer/DownloadExcel";                         
                        } else {
                           $.dialog.alert("下載失敗!");
                        }
                    },
                    error: function
 
 (err) {
                         $.dialog.alert("下載失敗");
                    }
                });                             

// 後臺介面程式碼
 @RequestMapping(value="/SubmitExcelData",method = RequestMethod.POST)
    public String submitExcelData(HttpServletRequest request, HttpServletResponse response,String paramJson)throws
 
 IOException  {
        // 設定響應和請求編碼utf-8
        request.setCharacterEncoding("UTF-8");

        JSONObject jsonResult=new JSONObject();         // 返回介面端的json物件
        if (paramJson == null) {
            jsonResult.put("code","0");
            jsonResult.put("msg","失敗，傳入引數為空");
            return jsonResult.toString();
        }
        // 將引數資訊存入session中
        HttpSession session = request.getSession();
        try {
            session.setAttribute("param", paramJson);
            jsonResult.put("code","1");
            jsonResult.put("msg","成功！");
        } catch (Exception e) {
            jsonResult.put("code","0");
            jsonResult.put("msg","失敗，失敗原因："+e.getMessage());
            return jsonResult.toString();
        }
        return jsonResult.toString();
    }
@RequestMapping(value="/DownloadExcel")
    public void downloadExcel(HttpServletRequest request, HttpServletResponse response)throws IOException {
        // 設定響應和請求編碼utf-8
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");

        HttpSession session = request.getSession();
        String strData = (String) session.getAttribute("param");
        if (strData == null||strData.equals("")) {
            response.getWriter().write("失敗，失敗原因：引數為空！");
            return;
        }       
                // 建立Excel
                // 省略.......
                // region 解析base64位的編碼為圖片
                BASE64Decoder decoder = new BASE64Decoder();
                // 圖片base編碼解密
                byte[] byteImgs = decoder.decodeBuffer(strImgBase64);
                // 處理資料
                for (int j = 0; j < byteImgs.length; ++j) {
                    if (byteImgs[j] < 0) {
                        byteImgs[j] += 256;
                    }
                }
                // endregion              

                //region 設定返回標頭檔案
                String strFileName="data.xls";// 預設Excel名稱
                response.setContentType("application/octet-stream; charset=utf-8");
                if (request.getHeader("User-Agent").toLowerCase().indexOf("firefox") > 0){
                    response.setHeader("Content-Disposition", "attachment; filename="
                            +  new String(strFileName.getBytes("UTF-8"), "ISO8859-1"));// firefox瀏覽器
                } else if (request.getHeader("User-Agent").toUpperCase().indexOf("MSIE") > 0){
                    response.setHeader("Content-Disposition", "attachment; filename="
                            + URLEncoder.encode(strFileName, "UTF-8"));// IE瀏覽器
                }else{
                    response.setHeader("Content-disposition", "attachment;filename="+strFileName);
                }
                // endregion
                 response.flushBuffer();
                 workbook.write(response.getOutputStream());
            }
        } catch (Exception e) {
            response.getWriter().write("失敗，失敗原因："+e.getMessage());
        }
    }