JavaScript 之 使用 XMLHttpRequest 上传文件

    <div id="div1">
             <input type="file" id="uploadfile" style="width: 100px; height: 25px;" />
             <input id="b1" type="button" value="上传" style="display: inline-block; width: 40px; height: 25px;" />
         </div>

js脚本：

https://dvcs.w3.org/hg/xhr/raw-file/tip/Overview.html

http://dev.w3.org/2006/webapi/FileAPI/

 window.onload = function () {
     document.getElementById("uploadfile").addEventListener("change", function () {
         //1、获取所选的文件 暂时只选一个

         var filereader = new FileReader();
         filereader.onloadend = function (event) {
             console.log("a");
             var filedata = event.target.result;
             var request = new XMLHttpRequest();
             request.open("POST", "Handler1.ashx", true);
             var formdata = new FormData();
             formdata.append(file.name, file);
             request.send(formdata);
         }
         filereader.onloadstart = function (event) {
             console.log("b");

         }
         var file = document.getElementById("uploadfile").files[0];
         var fileblob = filereader.readAsArrayBuffer(file);
     }, true);
 }

C#

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
 using System.Text;
 using System.IO;
 using System.Data;
 namespace WebApplication1
 {
     /// <summary>
     /// Handler1 的摘要说明
     /// </summary>
     public class Handler1 : IHttpHandler
     {
         public byte[] buffer = null;
         public FileStream filestream = null;
         public void ProcessRequest(HttpContext context)
         {

             int length = Convert.ToInt32(context.Request.Files[].InputStream.Length);
             buffer = new byte[length];

             //context.Request.InputStream.Read(buffer, 0, length);
             context.Request.Files[].InputStream.Read(buffer, , length);

             string direcotry = System.Environment.CurrentDirectory;
             direcotry = context.Request.Path;
             direcotry = context.Request.MapPath("\\");
             string filename = context.Request.Files[].FileName;//文件名
             string hzm = filename.Substring(filename.LastIndexOf("."));//后缀名

             filestream = new FileStream(direcotry + DateTime.Now.Ticks.ToString() + hzm, FileMode.Create);
             filestream.Write(buffer, , buffer.Length);
             filestream.Flush();
             filestream.Close();
             context.Response.ContentType = "text/plain";
             context.Response.Write("Hello World");
         }

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