html5文件上传

htmL代码：

       <div class="row">   

      <input type="file" name="fileToUpload" id="fileToUpload" onchange="fileSelected();"/>  

    </div>   

    <div id="fileSize"></div>  

    <div id="fileType"></div>  

    <div class="row">  

      <input type="button" onclick="uploadFile()" value="上传" />  

    </div>  

    <div id="progressNumber"></div>  

                <progress max="100" id="progre" value="0"></progress>  

                <br />  

                <asp:Image ID="Image1"  Style="max-width:130px" runat="server" />  

                <asp:HiddenField ID="hfimg" value="" runat="server" />  

JS代码：

      <script type="text/javascript">  

        function fileSelected() {  

            var file = document.getElementById('fileToUpload').files[0];  

            if (file) {  

                var fileSize = 0;  

                if (file.size > 1024 * 1024)  

                    fileSize = (Math.round(file.size * 100 / (1024 * 1024)) / 100).toString() + 'MB';  

                else  

                    fileSize = (Math.round(file.size * 100 / 1024) / 100).toString() + 'KB';  

                document.getElementById('fileSize').innerHTML = '文件大小: ' + fileSize;  

                document.getElementById('fileType').innerHTML = '文件类型: ' + file.type;  

            }  

        }  

        function uploadFile() {  

            var fd = new FormData();  

            fd.append("fileToUpload", document.getElementById('fileToUpload').files[0]);  

            var xhr = new XMLHttpRequest();  

            xhr.upload.addEventListener("progress", uploadProgress, false);  

            xhr.addEventListener("load", uploadComplete, false);  

            xhr.addEventListener("error", uploadFailed, false);  

            xhr.addEventListener("abort", uploadCanceled, false);  

            xhr.open("POST", "/handler/h5upload.ashx");  

            xhr.send(fd);  

        function uploadProgress(evt) {  

            if (evt.lengthComputable) {  

                var percentComplete = Math.round(evt.loaded * 100 / evt.total);  

                document.getElementById('progressNumber').innerHTML = percentComplete.toString() + '%';  

                document.getElementById('progre').value = percentComplete;  

            else {  

                document.getElementById('progressNumber').innerHTML = 'unable to compute';  

        function uploadComplete(evt) {  

            /* This event is raised when the server send back a response */   

          var json =eval("("+ evt.target.responseText+")");  

          if (json.status=="no") {  

              alert(json.info);  

          }else{  

            document.getElementById("<%=Image1.ClientID%>").src = json.path;  

            document.getElementById("<%=hfimg.ClientID%>").value = json.path;   

          }  

        function uploadFailed(evt) {  

            alert("There was an error attempting to upload the file.");  

        function uploadCanceled(evt) {  

            alert("The upload has been canceled by the user or the browser dropped the connection.");  

    </script>  

后台ashx代码：

    context.Response.ContentType = "text/plain";  

            HttpPostedFile  file =context. Request.Files["fileToUpload"];  

            String fileName = file.FileName;  

            String fileExt = Path.GetExtension(fileName).ToLower();  

            //定义允许上传的文件扩展名  

            Hashtable extTable = new Hashtable();  

            extTable.Add("image", "gif,jpg,jpeg,png,bmp");  

            extTable.Add("flash", "swf,flv");  

            extTable.Add("media", "swf,flv,mp3,wav,wma,wmv,mid,avi,mpg,asf,rm,rmvb");  

            extTable.Add("file", "doc,docx,xls,xlsx,ppt,htm,html,txt,zip,rar,gz,bz2");  

            if (String.IsNullOrEmpty(fileExt) || Array.IndexOf(((String)extTable["image"]).Split(','), fileExt.Substring(1).ToLower()) == -1)  

            {  

                context.Response.Write(LitJson.JsonMapper.ToJson(new { status="no", info = "上传文件扩展名是不允许的扩展名。  

只允许" + ((String)extTable["image"]) + "格式。" }));  

                return;  

            string dirpath = "/upload/"+DateTime.Now.ToString("yyyyMMdd")+"/";  

            if (!Directory.Exists(context.Server.MapPath( dirpath)))  

                Directory.CreateDirectory(context.Server.MapPath(dirpath));  

            String newFileName = DateTime.Now.ToString("yyyyMMddHHmmss_ffff", DateTimeFormatInfo.InvariantInfo) + fileExt;  

            file.SaveAs(context.Server.MapPath(dirpath) + newFileName);  

            context.Response.Write(LitJson.JsonMapper.ToJson(new { status="ok",path = dirpath+newFileName}));