input實(shí)現(xiàn)文件的上傳蓄愁，設(shè)置input中的type="file"
設(shè)置input的
type="file"。accept屬性設(shè)置支持上傳文件的類型撮抓。
accept支持上傳MIME類型的文件，多個(gè)MIME類型用英文逗號(hào)分開丹拯。multiple屬性:設(shè)置多文件上傳
設(shè)置multiple="multiple"，可一次傳多個(gè)乖酬，默認(rèn)省略不寫，一次傳一個(gè)咬像。
多個(gè)文件時(shí)，其value值為第一個(gè)文件的虛擬路徑肮柜。
限制文件的類型，前臺(tái)后臺(tái)都可以做审洞，前臺(tái)推薦這種待讳，后臺(tái)的一般截取文件后綴名，字符比較耙箍，貌似麻煩了酥馍，還不如直接上來(lái)就只能上傳指定類型的文件省事。
常用的MIME類型如下：
文件后綴名 & MIME名稱
*.3gpp audio/3gpp, video/3gpp
*.ac3 audio/ac3
*.asf allpication/vnd.ms-asf
*.au audio/basic
*.css text/css
*.csv text/csv
*.doc application/msword
*.dot application/msword
*.dtd application/xml-dtd
*.dwg image/vnd.dwg
*.dxf image/vnd.dxf
*.gif image/gif
*.htm text/html
*.html text/html
*.jp2 image/jp2
*.jpe image/jpeg
*.jpeg image/jpeg
*.jpg image/jpeg
*.js text/javascript, application/javascript
*.json application/json
*.mp2 audio/mpeg, video/mpeg
*.mp3 audio/mpeg
*.mp4 audio/mp4, video/mp4
*.mpeg video/mpeg
*.mpg video/mpeg
*.mpp application/vnd.ms-project
*.ogg application/ogg, audio/ogg
*.pdf application/pdf
*.png image/png
*.pot application/vnd.ms-powerpoint
*.pps application/vnd.ms-powerpoint
*.ppt application/vnd.ms-powerpoint
*.rtf application/rtf, text/rtf
*.svf image/vnd.svf
*.tif image/tiff
*.tiff image/tiff
*.txt text/plain
*.wdb application/vnd.ms-works
*.wps application/vnd.ms-works
*.xhtml application/xhtml+xml
*.xlc application/vnd.ms-excel
*.xlm application/vnd.ms-excel
*.xls application/vnd.ms-excel
*.xlt application/vnd.ms-excel
*.xlw application/vnd.ms-excel
*.xml text/xml, application/xml
*.zip aplication/zip
*.xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
