来之不易的js图片上传预览代码

<%@ 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 XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
    <title>图片上传预览js代码--来之不易</title>
</head>
<body>
    <div id="divPreview">
        <img id="imgHeadPhoto" src="noperson.jpg" style="width: 160px; height: 170px; border: solid 1px #d2e2e2;" alt="" />
    </div>
    <input type="file" onchange="PreviewImage(this,'imgHeadPhoto','divPreview');" size="20" />
    <script type="text/javascript">
        //js本地图片预览,兼容ie[6-9]、火狐、Chrome17+、Opera11+、Maxthon3
        function PreviewImage(fileObj, imgPreviewId, divPreviewId) {
            var allowExtention = ".jpg,.bmp,.gif,.png"; //允许上传文件的后缀名document.getElementById("hfAllowPicSuffix").value;
            var extention = fileObj.value.substring(fileObj.value.lastIndexOf(".") + 1).toLowerCase();
            var browserVersion = window.navigator.userAgent.toUpperCase();
            if (allowExtention.indexOf(extention) > -1) {
                if (fileObj.files) {//HTML5实现预览,兼容chrome、火狐7+等
                    if (window.FileReader) {
                        var reader = new FileReader();
                        reader.onload = function (e) {
                            document.getElementById(imgPreviewId).setAttribute("src", e.target.result);
                        }
                        reader.readAsDataURL(fileObj.files[0]);
                    } else if (browserVersion.indexOf("SAFARI") > -1) {
                        alert("不支持Safari6.0以下浏览器的图片预览!");
                    }
                } else if (browserVersion.indexOf("MSIE") > -1) {
                    if (browserVersion.indexOf("MSIE 6") > -1) {//ie6
                        document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);
                    } else {//ie[7-9]
                        fileObj.select();
                        if (browserVersion.indexOf("MSIE 9") > -1)
                            fileObj.blur(); //不加上document.selection.createRange().text在ie9会拒绝访问
                        var newPreview = document.getElementById(divPreviewId + "New");
                        if (newPreview == null) {
                            newPreview = document.createElement("div");
                            newPreview.setAttribute("id", divPreviewId + "New");
                            newPreview.style.width = document.getElementById(imgPreviewId).width + "px";
                            newPreview.style.height = document.getElementById(imgPreviewId).height + "px";
                            newPreview.style.border = "solid 1px #d2e2e2";
                        }
                        newPreview.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale',src='" + document.selection.createRange().text + "')";
                        var tempDivPreview = document.getElementById(divPreviewId);
                        tempDivPreview.parentNode.insertBefore(newPreview, tempDivPreview);
                        tempDivPreview.style.display = "none";
                    }
                } else if (browserVersion.indexOf("FIREFOX") > -1) {//firefox
                    var firefoxVersion = parseFloat(browserVersion.toLowerCase().match(/firefox\/([\d.]+)/)[1]);
                    if (firefoxVersion < 7) {//firefox7以下版本
                        document.getElementById(imgPreviewId).setAttribute("src", fileObj.files[0].getAsDataURL());
                    } else {//firefox7.0+                    
                        document.getElementById(imgPreviewId).setAttribute("src", window.URL.createObjectURL(fileObj.files[0]));
                    }
                } else {
                    document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);
                }
            } else {
                alert("仅支持" + allowExtention + "为后缀名的文件!");
                fileObj.value = ""; //清空选中文件
                if (browserVersion.indexOf("MSIE") > -1) {
                    fileObj.select();
                    document.selection.clear();
                }
                fileObj.outerHTML = fileObj.outerHTML;
            }
            return fileObj.value;    //返回路径
        }
    </script>

</body>

</html>

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