自己动手打造ajax图片上传(网上没有的)

<p> 
<label>上传图片</label> 
<input class="ke-input-text" type="text" id="url" value="" readonly="readonly" /> 
<input type="button" id="uploadButton" value="Upload" /> 
</p> 
<script type="text/javascript"> 
$(function() { 
$('.inp_fileToUpload').change(function() { 
var formdata = new FormData(); 
var v_this = $(this); 
var fileObj = v_this.get(0).files; 
url = "/upload/upload_json.ashx"; 
//var fileObj=document.getElementById("fileToUpload").files; 
formdata.append("imgFile", fileObj[0]); 
jQuery.ajax({ 
url : url, 
type : 'post', 
data : formdata, 
cache : false, 
contentType : false, 
processData : false, 
dataType : "json", 
success : function(data) { 
if (data.error == 0) { 
v_this.parent().children(".img_upload").attr("src", data.url); 
//$("#img").attr("src",data.url); 
} 
} 
}); 
return false; 
}); 
}); 
</script>

<p> 
<label>ajax上传</label> 
<input type="file" name="fileToUpload" id="fileToUpload" class="inp_fileToUpload" multiple="multiple"/> 
<img src="/UploadFiles/2021-04-02/lb_head.jpg">



说明：这种方法目前测试支持IE8/9,谷歌，兼容比方法1好。建议采用方法2
文件上传后台处理代码（asp.net版）




<%@ webhandler Language="C#" class="Upload" %> 

using System; 
using System.Collections; 
using System.Web; 
using System.IO; 
using System.Globalization; 
using LitJson; 
public class Upload : IHttpHandler 
{ 
private HttpContext context; 
public void ProcessRequest(HttpContext context) 
{ 
String aspxUrl = context.Request.Path.Substring(0, context.Request.Path.LastIndexOf("/") + 1); 

//文件保存目录路径 
String savePath = "attached/"; 
//文件保存目录URL 
String saveUrl = aspxUrl + "attached/"; 
//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"); 
//最大文件大小 
int maxSize = 1000000; 
this.context = context; 
HttpPostedFile imgFile = context.Request.Files["imgFile"]; 
if (imgFile == null) 
{ 
showError("请选择文件。"); 
} 
String dirPath = context.Server.MapPath(savePath); 
if (!Directory.Exists(dirPath)) 
{ 
showError("上传目录不存在。"); 
} 
String dirName = context.Request.QueryString["dir"]; 
if (String.IsNullOrEmpty(dirName)) { 
dirName = "image"; 
} 
if (!extTable.ContainsKey(dirName)) { 
showError("目录名不正确。"); 
} 
String fileName = imgFile.FileName; 
String fileExt = Path.GetExtension(fileName).ToLower(); 
if (imgFile.InputStream == null || imgFile.InputStream.Length > maxSize) 
{ 
showError("上传文件大小超过限制。"); 
} 
if (String.IsNullOrEmpty(fileExt) || Array.IndexOf(((String)extTable[dirName]).Split(','), fileExt.Substring(1).ToLower()) == -1) 
{ 
showError("上传文件扩展名是不允许的扩展名。\n只允许" + ((String)extTable[dirName]) + "格式。"); 
} 
//创建文件夹 
dirPath += dirName + "/"; 
saveUrl += dirName + "/"; 
if (!Directory.Exists(dirPath)) { 
Directory.CreateDirectory(dirPath); 
} 
String ymd = DateTime.Now.ToString("yyyyMMdd", DateTimeFormatInfo.InvariantInfo); 
dirPath += ymd + "/"; 
saveUrl += ymd + "/"; 
if (!Directory.Exists(dirPath)) { 
Directory.CreateDirectory(dirPath); 
} 
String newFileName = DateTime.Now.ToString("yyyyMMddHHmmss_ffff", DateTimeFormatInfo.InvariantInfo) + fileExt; 
String filePath = dirPath + newFileName; 
imgFile.SaveAs(filePath); 
String fileUrl = saveUrl + newFileName; 
Hashtable hash = new Hashtable(); 
hash["error"] = 0; 
hash["url"] = fileUrl; 
context.Response.AddHeader("Content-Type", "text/html; charset=UTF-8"); 
context.Response.Write(JsonMapper.ToJson(hash)); 
context.Response.End(); 
} 
private void showError(string message) 
{ 
Hashtable hash = new Hashtable(); 
hash["error"] = 1; 
hash["message"] = message; 
context.Response.AddHeader("Content-Type", "text/html; charset=UTF-8"); 
context.Response.Write(JsonMapper.ToJson(hash)); 
context.Response.End(); 
} 
public bool IsReusable 
{ 
get 
{ 
return true; 
} 
} 
}