实现代码一：
XML/HTML代码
- <script
language=JavaScript>
- var flag=false;
- function DrawImage(ImgD){
- var image=new Image();
image.src=ImgD.src; - if(image.width>0 && image.height>0){
flag=true; - if(image.width/image.height>= 120/80){
- if(image.width>120){
ImgD.width=120;
ImgD.height=(image.height*120)/image.width; - }else{
ImgD.width=image.width;
ImgD.height=image.height; - }
ImgD.alt=image.width+"×"+image.height; - }
- else{
- if(image.height>80){
ImgD.height=80;
ImgD.width=(image.width*80)/image.height; - }else{
ImgD.width=image.width;
ImgD.height=image.height; - }
ImgD.alt=image.width+"×"+image.height; - }
- }
- /**//**//**//*else{
ImgD.src="";
ImgD.alt=""
- }*/
- }
- function FileChange(Value){
- flag=false;
- document.all.uploadimage.width=10;
- document.all.uploadimage.height=10;
- document.all.uploadimage.alt="";
- document.all.uploadimage.src=Value;
- }
- function BeforeUpLoad(){
- if(flag) alert("OK");else alert("FAIL");
- }
- </script>
- <INPUT
style="WIDTH: 143px; HEIGHT: 18px"
type=file
size=8
name=pic
onchange="javascript:FileChange(this.value);">
- <IMG
id=uploadimage
height=10
width=10
src=""
onload="javascript:DrawImage(this);"
><BR>
- <Button
onclick="javascript:BeforeUpLoad();">提交</Button>
实现代码二：
XML/HTML代码
- <input
id="file"
type="file"
onfocus="javascript:ShowImage(this.value,document.getElementById('img'))">
- <br
/>
- <img
id="img"
STYLE="visibility:hidden"
height="100px"
width="100px">
- <script
language="javascript"
type="text/javascript">
- function ShowImage(value,img)
- {
- //alert(value);
- //检测盘符
- //alert(value.indexOf(':'));
- //检测文件是否有扩展名
- //alert(value.length-value.lastIndexOf('.'));
- //取文件扩展名
- //alert(value.substr(value.length-3,3));
- //检测文件扩展名是否合法
- //alert(CheckExt(value.substr(value.length-3,3)));
- if(value.length>5&&value.indexOf(':')==1&& (value.length-value.lastIndexOf('.'))==4&&CheckExt(value.substr(value.length-3,3)))
- {
img.src=value;
img.alt="本地图片预览";
img.style.visibility="visible"; - }
- else
- {
img.style.visibility="hidden"; - }
- }
- //检查扩展名是否合法,合法返回True
- function CheckExt(ext)
- {
- //这里设置允许的扩展名
- var AllowExt="jpg|gif|jpeg|png|bmp";
- var ExtOK=false;
- var ArrayExt;
- if(AllowExt.indexOf('|')!=-1)
- {
ArrayExt=AllowExt.split('|'); - for(i=0;i<ArrayExt.length;i++)
- {
- if(ext.toLowerCase()==ArrayExt)
- {
ExtOK=true; - break;
- }
- }
- }
- else
- {
ArrayExt=AllowExt; - if(ext.toLowerCase()==ArrayExt)
- {
ExtOK=true; - }
- }
- return ExtOK;
- }
- </script>
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