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js 图片预览

2016-05-14 17:50 344 查看 
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'img.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

</head>

<script type="text/javascript">
//下面用于图片上传预览功能
function setImagePreview(avalue) {
debugger;
var docObj = document.getElementById("doc");
//检查图片类型
if(!checkType(docObj)){
return ;
}

var imgObjPreview = document.getElementById("preview");
if (docObj.files && docObj.files[0]) {
//火狐下，直接设img属性
imgObjPreview.style.display = 'block';
imgObjPreview.style.width = '150px';
imgObjPreview.style.height = '180px';
//imgObjPreview.src = docObj.files[0].getAsDataURL();

//火狐7以上版本不能用上面的getAsDataURL()方式获取，需要一下方式
imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);
} else {
//IE下，使用滤镜
docObj.select();
var imgSrc = document.selection.createRange().text;
var localImagId = document.getElementById("localImag");
//必须设置初始大小
localImagId.style.width = "150px";
localImagId.style.height = "180px";
//图片异常的捕捉，防止用户修改后缀来伪造图片
try {
localImagId.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;
} catch (e) {
alert("您上传的图片格式不正确，请重新选择!");
return false;
}
imgObjPreview.style.display = 'none';
document.selection.empty();
}
return true;
}

//检查图片类型
function checkType(file){
var f = file.value;
if(!f){
alert("请上传图片");
return false;
} else{
if(!/\.(gif|jpg|jpeg|png|bmp|GIF|JPG|PNG)$/.test(f))
{
alert("图片类型必须是.gif,jpeg,jpg,png中的一种");
return false;
}
return true;
}
}
</script>
</head>

<body>
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tbody>
<tr>
<td height="101" align="center">
<div id="localImag">
<img id="preview" src="http://avatar.csdn.net/2/D/C/1_u012965203.jpg" width="150" height="180"
style="display: block; width: 150px; height: 180px;">
</div>
</td>
</tr>
<tr>
<td align="center" style="padding-top:10px;"><input type="file" name="file" id="doc" style="width:150px;"
onchange="javascript:setImagePreview();">
</td>
</tr>
</tbody>
</table>
</body>
</html>
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