图片：
Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
视频：
Content.Headers.ContentType = new MediaTypeHeaderValue("video/mp4")
.docx
Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.wordprocessingml.document");
| 文件后缀 | 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 如果还是用application/vnd.ms-excel 谷歌和ie都不改名，识别未xlsx 但是火狐会自动改名未 xls 文件 xlsx请使用这个新版的 |
| .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 |
| .zip | application/zip |
| .tar | application/x-tar |