JavaScript 之 使用 XMLHttpRequest 上传文件

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

 1 window.onload = function () {
 2     document.getElementById("uploadfile").addEventListener("change", function () {
 3         //1、获取所选的文件 暂时只选一个
 4 
 5         var filereader = new FileReader();
 6         filereader.onloadend = function (event) {
 7             console.log("a");
 8             var filedata = event.target.result;
 9             var request = new XMLHttpRequest();
10             request.open("POST", "Handler1.ashx", true);
11             var formdata = new FormData();
12             formdata.append(file.name, file);
13             request.send(formdata);
14         }
15         filereader.onloadstart = function (event) {
16             console.log("b");
17 
18         }
19         var file = document.getElementById("uploadfile").files[0];
20         var fileblob = filereader.readAsArrayBuffer(file);
21     }, true);
22 }

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using System.Text;
 6 using System.IO;
 7 using System.Data;
 8 namespace WebApplication1
 9 {
10     /// <summary>
11     /// Handler1 的摘要说明
12     /// </summary>
13     public class Handler1 : IHttpHandler
14     {
15         public byte[] buffer = null;
16         public FileStream filestream = null;
17         public void ProcessRequest(HttpContext context)
18         {
19 
20             int length = Convert.ToInt32(context.Request.Files[0].InputStream.Length);
21             buffer = new byte[length];
22 
23             //context.Request.InputStream.Read(buffer, 0, length);
24             context.Request.Files[0].InputStream.Read(buffer, 0, length);
25 
26             string direcotry = System.Environment.CurrentDirectory;
27             direcotry = context.Request.Path;
28             direcotry = context.Request.MapPath("\\");
29             string filename = context.Request.Files[0].FileName;//文件名
30             string hzm = filename.Substring(filename.LastIndexOf("."));//后缀名
31 
32             filestream = new FileStream(direcotry + DateTime.Now.Ticks.ToString() + hzm, FileMode.Create);
33             filestream.Write(buffer, 0, buffer.Length);
34             filestream.Flush();
35             filestream.Close();
36             context.Response.ContentType = "text/plain";
37             context.Response.Write("Hello World");
38         }
39 
40         public bool IsReusable
41         {
42             get
43             {
44                 return false;
45             }
46         }
47     }
48 }