异步带进度条——提交文件

前台代码:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
    <style type="text/css">
        #div1{300px;height:30px;border:1px solid #000;position:relative;}
        #div2{0px;height:30px;background:#CCC;}
        #div3 {
             300px;
            height: 30px;
            line-height: 30px;
            text-align: center;
            position: absolute;
            left:0px;top:0px;
        }
    </style>
</head>
<body>
 <input type="file" id="file"/><input type="button" id="btnFile" value="上传" />
   <!--进度条-->
    <div id="div1">
        <div id="div2"></div>
        <div id="div3">0%</div>
    </div>
 
</body>
</html>
<script type="text/javascript">
    var file = document.getElementById("file");
    var btnFile = document.getElementById("btnFile");
    var div1 = document.getElementById("div1");
    var div2 = document.getElementById("div2");
    var div3 = document.getElementById("div3");
    
    btnFile.onclick = function () {
        var xml = new XMLHttpRequest();
        xml.onload = function () {
            alert(xml.responseText);
        }
        //上传进度条事件
        var oUpload = xml.upload;        
        oUpload.onprogress = function (ev) {
            //console.log(ev.total + ":" + ev.loaded);//ev.loaded是已经上传的 ev.total是总的
            var iScale = ev.loaded / ev.total;//计算出比例
            div2.style.width = 300 * iScale + "px";
            div3.innerHTML = iScale*100 + "%";
        }

        xml.open("post", "HandlerFiles.ashx", true);
        xml.setRequestHeader('X-Request-Width', 'XMLHttpRequest');
        var oFormData = new FormData();       
        oFormData.append("file",file.files[0]);      
        xml.send(oFormData);
    }
</script>

后台代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Ajax无刷新上传
{
    /// <summary>
    /// HandlerFiles 的摘要说明
    /// </summary>
    public class HandlerFiles : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";
            int rec = context.Request.Files.Count;
            if (context.Request.Files.Count > 0)
            {
                HttpPostedFile  files = context.Request.Files[0];
                if (files.ContentLength > 0)
                {
                    int n=files.ContentLength;
                    string fileName = files.FileName;
                    files.SaveAs(context.Request.MapPath("files/"+Guid.NewGuid().ToString()+"_"+fileName));
                    context.Response.Write("上传完毕!");
                    context.Response.End();
                }
                else { context.Response.Write("选择的文件不能小于0字节"); context.Response.End(); }

                
            }
            else {
                context.Response.Write("请先选择上传文件");
                context.Response.End();
            }

        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

GitHub项目链接:https://github.com/shuai7boy/AjaxUploadFiles