返回格式是根据您响应头判断的

设置EXCEL文档的MIME类型

MSExcel有以下观察到的MIME类型：

application/vnd.ms-excel

(正式)

application/msexcel

application/x-msexcel

application/x-ms-excel

application/x-excel

application/x-dos_ms_excel

application/xls

application/x-xls

application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

(Xlsx)

response.setContentType("application/vnd.ms-excel");