需求：
上传文件的时候限制上传文件类型，
实现：
涉及文件：
写道
扩展名 MIME 描述 *.3gpp audio/3gpp, video/3gpp 3GPP Audio/Video *.ac3 audio/ac3 AC3 Audio *.asf allpication/vnd.ms-asf Advanced Streaming Format *.au audio/basic AU Audio *.css text/css Cascading Style Sheets *.csv text/csv Comma Separated Values *.doc application/msword MS Word Document *.dot application/msword MS Word Template *.dtd application/xml-dtd Document Type Definition *.dwg image/vnd.dwg AutoCAD Drawing Database *.dxf image/vnd.dxf AutoCAD Drawing Interchange Format *.gif image/gif Graphic Interchange Format *.htm text/html HyperText Markup Language *.html text/html HyperText Markup Language *.jp2 image/jp2 JPEG-2000 *.jpe image/jpeg JPEG *.jpeg image/jpeg JPEG *.jpg image/jpeg JPEG *.js text/javascript, application/javascript JavaScript *.json application/json JavaScript Object Notation *.mp2 audio/mpeg, video/mpeg MPEG Audio/Video Stream, Layer II *.mp3 audio/mpeg MPEG Audio Stream, Layer III *.mp4 audio/mp4, video/mp4 MPEG-4 Audio/Video *.mpeg video/mpeg MPEG Video Stream, Layer II *.mpg video/mpeg MPEG Video Stream, Layer II *.mpp application/vnd.ms-project MS Project Project *.ogg application/ogg, audio/ogg Ogg Vorbis *.pdf application/pdf Portable Document Format *.png image/png Portable Network Graphics *.pot application/vnd.ms-powerpoint MS PowerPoint Template *.pps application/vnd.ms-powerpoint MS PowerPoint Slideshow *.ppt application/vnd.ms-powerpoint MS PowerPoint Presentation *.rtf application/rtf, text/rtf Rich Text Format *.svf image/vnd.svf Simple Vector Format *.tif image/tiff Tagged Image Format File *.tiff image/tiff Tagged Image Format File *.txt text/plain Plain Text *.wdb application/vnd.ms-works MS Works Database *.wps application/vnd.ms-works Works Text Document *.xhtml application/xhtml+xml Extensible HyperText Markup Language *.xlc application/vnd.ms-excel MS Excel Chart *.xlm application/vnd.ms-excel MS Excel Macro *.xls application/vnd.ms-excel MS Excel Spreadsheet *.xlt application/vnd.ms-excel MS Excel Template *.xlw application/vnd.ms-excel MS Excel Workspace *.xml text/xml, application/xml Extensible Markup Language *.zip aplication/zip Compressed Archive