office 所有后缀对应的 content-type
| 后缀 | MIME Type |
| .doc | application/msword |
| .dot | application/msword |
| .docx | application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| .dotx | application/vnd.openxmlformats-officedocument.wordprocessingml.template |
| .docm | application/vnd.ms-word.document.macroEnabled.12 |
| .dotm | application/vnd.ms-word.template.macroEnabled.12 |
| .xls | application/vnd.ms-excel |
| .xlt | application/vnd.ms-excel |
| .xla | application/vnd.ms-excel |
| .xlsx | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet |
| .xltx | application/vnd.openxmlformats-officedocument.spreadsheetml.template |
| .xlsm | application/vnd.ms-excel.sheet.macroEnabled.12 |
| .xltm | application/vnd.ms-excel.template.macroEnabled.12 |
| .xlam | application/vnd.ms-excel.addin.macroEnabled.12 |
| .xlsb | application/vnd.ms-excel.sheet.binary.macroEnabled.12 |
| .ppt | application/vnd.ms-powerpoint |
| .pot | application/vnd.ms-powerpoint |
| .pps | application/vnd.ms-powerpoint |
| .ppa | application/vnd.ms-powerpoint |
| .pptx | application/vnd.openxmlformats-officedocument.presentationml.presentation |
| .potx | application/vnd.openxmlformats-officedocument.presentationml.template |
| .ppsx | application/vnd.openxmlformats-officedocument.presentationml.slideshow |
| .ppam | application/vnd.ms-powerpoint.addin.macroEnabled.12 |
| .pptm | application/vnd.ms-powerpoint.presentation.macroEnabled.12 |
| .potm | application/vnd.ms-powerpoint.presentation.macroEnabled.12 |
| .ppsm | application/vnd.ms-powerpoint.slideshow.macroEnabled.12 |
原文：https://blog.csdn.net/xiaoranzhizhu/article/details/70473734
