原因：ajax请求只是个“字符型”的请求，即请求的内容是以文本类型存放的。文件的下载是以二进制形式进行的，ajax没法解析后台返回的文件流，所以无法处理二进制流response输出来下载文件。
解决方法：使用form表单提交实现文件下载
1，后台代码实现方法：
// 生成excel文件 ???@RequestMapping(value = "/study", method = RequestMethod.POST) ???public void study(@RequestBody ParamVO paramVO, HttpServletResponse response) throws UnsupportedEncodingException { ???????response.setContentType("application/octet-stream;charset=utf-8"); ???????response.setContentType("application/vnd.ms-excel"); ???????response.setHeader("Content-disposition", "attachment;filename=" + new String(paramVO.getFileName().getBytes("utf-8"), "iso-8859-1")); ???????try (ByteArrayOutputStream bos = templateService.excel(paramVO); ???????????????BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream())) { ???????????out.write(bos.toByteArray()); ???????????response.setHeader("Content-Length", String.valueOf(bos.toByteArray().length)); ???????} catch (Exception e) { ???????????e.printStackTrace(); ???????} ???}2，前端页面使用Ajax下载文件
var xhr = new XMLHttpRequest(); ???????xhr.open(‘post‘, ‘http://localhost:8080/user/export‘, true); ???????xhr.responseType = ‘blob‘; ???????xhr.setRequestHeader(‘Content-Type‘, ‘application/json;charset=utf-8‘); ???????xhr.onload = function () { ???????????if (this.status == 200) { ???????????????var blob = this.response; ???????????????var a = document.createElement(‘a‘); ???????????????var url = window.URL.createObjectURL(blob); ???????????????a.href = url; ???????????????//设置文件名称 ???????????????a.download = ‘用户信息.xls‘; ???????????????a.click(); ???????????} ???????} ???????xhr.send(JSON.stringify({ ??????????"type" : 1, ??????????"startDate" : "2018-01-01", ??????????"endDate" : "2018-12-31" ???????})); ???}或者前端也可以这样实现：
{ ???????var xhr = new XMLHttpRequest(); ?????xhr.open(‘post‘, ‘http://localhost:8080/user/export‘, true); ?????xhr.responseType = ‘blob‘; ?????xhr.onload = function () { ?????var blob = this.response; ?????if(window.navigator.msSaveOrOpenBlob){ ?????????window.navigator.msSaveBlob(blob, ‘msSaveBlob_testFile.txt‘); ?????}else{ ?????????var link = document.createElement(‘a‘); ?????????link.href = window.URL.createObjectURL(blob); ?????????link.download = ‘msSaveBlob_testFile.txt‘; ?????????link.click(); ?????????window.URL.revokeObjectURL(link.href); ?????} ?????xhr.send(null); ?????}}本文转自：https://blog.csdn.net/hj7jay/article/details/86309968
用ajax下载字节流形式的excel文件
原文地址：https://www.cnblogs.com/nizuimeiabc1/p/10534415.html