【springmvc】通过POI下载文件的实现过程

整体代码实现思路

1. 首先在jsp页面中，设置一个导出功能按钮，在导出功能函数中，通过window.location.href的方式打开一个新的页面；
2. 后台的export函数中做两部分操作
3. 操作一：将数据库中的数据读取出来，写入到一个HSSFWorkbook文件中
4. 操作二：将HSSFWorkbook文件，添加到response的out流中，返回给前台新打开的页面。从而完成下载功能

前台代码

//导出按钮
    function exportClick() {
    	var beginDate = $('#beginDate').datebox('getValue');
        var endDate = $('#endDate').datebox('getValue');
        if(beginDate != null && beginDate != "" && endDate != null && endDate != "") {
        	layer.confirm('是否导出时间为'+beginDate+'至'+endDate+'的奖惩信息？', {
                btn: ['确认', '取消'] //按钮
            }, function () {
            	layer.close(layer.index);
            	window.location.href = "${pageContext.request.contextPath}/staff/policeReward/export.do?beginDate=" + beginDate+"&endDate=" + endDate;
            });
        }else {
        	layer.msg("请选择导出时间范围", {icon: 2});
        }
    }

后台代码

    /**
     * 导出日志查询列表
     * @author 老魏
     * @date 2018-10-09
     * @param pageParams 		分页参数
     * @return
     */
    @RequestMapping(value = "/export")
    public void export(HttpServletRequest request, String beginDate,String endDate,HttpServletResponse response, HttpSession session){
        try {
        	SessionInfo sessionInfo = (SessionInfo) session.getAttribute("sessionInfo");
            Long userID = sessionInfo.getUserId();
             
            HSSFWorkbook workbook = new HSSFWorkbook();
            HSSFSheet sheet = workbook.createSheet("奖惩信息列表");
            HSSFRow headRow = sheet.createRow(0);

            //这是一些要导出列的标题
            String[] title = new String[] { "奖惩名称","批准日期","文件名","文件号","人数","具体人员"};
            for (int i = 0; i < title.length; i++) {
                headRow.createCell(i).setCellValue(title[i]);
            }
            //要导出的数据对象集合
            //注意：这里要写成你自己的数据源。
            List<ViewRewardExport> list = viewRewardService.queryList(beginDate,endDate,userID);
            HSSFCellStyle cellStyle = workbook.createCellStyle();  
            HSSFDataFormat format = workbook.createDataFormat();  
            cellStyle.setDataFormat(format.getFormat("@"));  
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            if (list != null && list.size() > 0) {
                for (ViewRewardExport log : list) {
                    HSSFRow dataRow = sheet.createRow(sheet.getLastRowNum() + 1);
                    this.setCellStyle(workbook,dataRow.createCell(0),log.getRewardCodeName(),cellStyle);
                    this.setCellStyle(workbook,dataRow.createCell(1),sdf.format(log.getApproveDate()),cellStyle);
                    this.setCellStyle(workbook,dataRow.createCell(2),log.getFileName(),cellStyle);
                    this.setCellStyle(workbook,dataRow.createCell(3),log.getFileCode(),cellStyle);
                    this.setCellStyle(workbook,dataRow.createCell(4),log.getAmount().toString(),cellStyle);
                    this.setCellStyle(workbook,dataRow.createCell(5),log.getNames(),cellStyle);
                }
            }
            sheet.autoSizeColumn(1, true);
            //对象置空
            list = null;
            response.reset();
            response.setContentType("application/ms-excel;charset=UTF-8");
            response.setHeader("Content-Disposition", "attachment;filename=".concat(String.valueOf(URLEncoder.encode("奖惩信息列表.xls", "UTF-8"))));
            try {
                workbook.write(response.getOutputStream());
                response.getOutputStream().flush();
            } catch (Exception e) {
            	log.error("奖惩信息列表Excel导出出错", e);
            }finally{
                if(workbook!=null){
                    workbook.close();
                }
                if(response.getOutputStream()!=null){
                    response.getOutputStream().close();
                }
            }
        } catch (Exception ce) {
        	log.error("奖惩信息列表Excel导出出错", ce);
        }
    }
    //统一处理cell格式函数
    public HSSFCell setCellStyle(HSSFWorkbook workbook,HSSFCell cell,String value,HSSFCellStyle cellStyle){
        cell.setCellStyle(cellStyle);
        cell.setCellValue(value);
        return cell;
    }