本次使用AJAXUPLOAD做为上传客户端无刷上传插件，其最新版本为3.9，官方地址：http://valums.com/ajax-upload/

在页面中引入 jquery.min.1.4.2.js 和 ajaxupload.js

?

<script src="Scripts/jquery-1.4.2.min.js" type="text/javascript"></script>
<script src="Scripts/ajaxupload3.9.js" type="text/javascript"></script>

?HTML 代码：

<style type="text/css">
        #txtFileName {
            width: 300px;
        }
        .btnsubmit{border-bottom: #cc4f00 1px solid; border-left: #ff9000 1px solid;border-top: #ff9000 1px solid;   border-right: #cc4f00 1px solid;text-align: center; padding: 2px 10px; line-height: 16px; background: #e36b0f;  height: 24px; color: #fff; font-size: 12px; cursor: pointer;}
    </style>

上传图片：<input type="text" id="txtFileName" /><div  id="btnUp" style="width:300px;" class=btnsubmit >浏览</div>

<div id="imglist"></div>

?js代 码：

<script type="text/javascript">

    $(function () {
        var button = $('#btnUp'), interval;
        new AjaxUpload(button, {
            //action: 'upload-test.php',文件上传服务器端执行的地址
            action: '/handler/AjaxuploadHandler.ashx',
            name: 'myfile',
            onSubmit: function (file, ext) {
                if (!(ext && /^(jpg|jpeg|JPG|JPEG)$/.test(ext))) {
                    alert('图片格式不正确,请选择 jpg 格式的文件!', '系统提示');
                    return false;
                }

                // change button text, when user selects file
                button.text('上传中');

                // If you want to allow uploading only 1 file at time,
                // you can disable upload button
                this.disable();

                // Uploding -> Uploading. -> Uploading...
                interval = window.setInterval(function () {
                    var text = button.text();
                    if (text.length < 10) {
                        button.text(text + '|');
                    } else {
                        button.text('上传中');
                    }
                }, 200);
            },
            onComplete: function (file, response) {
                //file 本地文件名称，response 服务器端传回的信息
                button.text('上传图片(只允许上传JPG格式的图片,大小不得大于150K)');
                
                window.clearInterval(interval);

                // enable upload button
                this.enable();

                var k = response.replace("<PRE>", "").replace("</PRE>", "");

                if (k == '-1') {
                    alert('您上传的文件太大啦!请不要超过150K');
                }
                else {
                    alert("服务器端传回的串："+k);
                    alert("本地文件名称："+file);
                    $("#txtFileName").val(k);
                    $("<img />").appendTo($('#imglist')).attr("src", k);
                }
            }
        });

    });
</script>

?服务器端 ajaxuploadhandler.ashx 代码

public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";

            HttpPostedFile postedFile = context.Request.Files[0];
            string savePath = "/upload/images/";
            int filelength = postedFile.ContentLength;
            int fileSize = 163600; //150K
            string fileName = "-1"; //返回的上传后的文件名
            if (filelength <= fileSize)
            {

                byte[] buffer = new byte[filelength];

                postedFile.InputStream.Read(buffer, 0, filelength);

                fileName = UploadImage(buffer, savePath, "jpg");

            }

            context.Response.Write(fileName);
        }

        public static string UploadImage(byte[] imgBuffer, string uploadpath, string ext)
        {
            try
            {
                System.IO.MemoryStream m = new MemoryStream(imgBuffer);

                if (!Direc