form表单的target，当iframe设置为隐藏时，可以实现当前页表单提交而部进行跳转刷新，代码如下：
<form action="提交的action" method="post" target="myIframe">
.....................
</form>
<iframe name="myIframe" style="display:none"></iframe>
提交到action后，action返回一串javascript语句
js:
String script = "<script>alert(‘hello!‘);</script>";
response.getOutputStream().write(script.getBytes("utf-8"));
alert("hello")将在当前页执行，原理是form提交后的结果在target指定的iframe里执行，iframe已经隐藏了，这样提交后的效果就和无刷新的效果一样。
input的file类型的accept属性的值
| 值 | 描述 |
|---|---|
| audio/* | 接受所有的声音文件。 |
| video/* | 接受所有的视频文件。 |
| image/* | 接受所有的图像文件。 |
| MIME_type | 一个有效的 MIME 类型，不带参数。请参阅 IANA MIME 类型，获得标准 MIME 类型的完整列表。 |
在上传文件的时候，需要限制指定的文件类型，accept这个属性，只在FF和chrome中有效。那么accept能限制哪些文件呢？见下表。
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 |
| 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 | application/zip | Compressed Archive |
实例 :
1.accept="image/gif, image/jpeg"
2.accept="application/msword"
3.accept="application/pdf"
4.accept="application/poscript"
5.accept="application/rtf"
6.accept="application/x-zip-compressed"
7.accept="audio/basic"
8.accept="audio/x-aiff"
9.accept="audio/x-mpeg"
10.accept="audio/x-pn/realaudio"
11.accept="audio/x-waw"
12.accept="image/gif"
13.accept="image/jpeg"
14.accept="image/tiff"
15.accept="image/x-ms-bmp"
16.accept="image/x-photo-cd"
17.accept="image/x-png"
18.accept="image/x-portablebitmap"
19.accept="image/x-portable-greymap"
20.accept="image/x-portable-pixmap"
21.accept="image/x-rgb"
22.accept="text/html"
23.accept="text/plain"
24.accept="video/quicktime"
25.accept="video/x-mpeg2"
26.accept="video/x-msvideo"
原文：https://www.cnblogs.com/Alex80/p/11108360.html