C# 异步上传图片案例

好久没写博客了,都感觉自己快堕落了!今天随性写一篇关于异步上传图片的程序及插件!

说是程序及插件,其实程序占大头,所谓的插件只是两个JS。分别为:jquery.html5upload.js 和 jquery.MultiFile.js

下载地址为:http://files.cnblogs.com/files/chenwolong/upload.rar

其实也没什么好说的,直接上源代码吧!

HTML展示如下:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="LLYY.WebForm1" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<script src="usercenter/js/jquery-1.11.1.min.js"></script>
<script type="text/javascript" src="usercenter/js/jquery-1.11.1.min.js"></script>
<script src="usercenter/js/jquery.html5upload.js" type="text/javascript"></script>
<script src="usercenter/js/jquery.MultiFile.js" type="text/javascript"></script> </head>
<body>
<form id="form1" runat="server">
<div>
<input id="mainPicNum" name="mainPicNum" type="file" class="" accept="gif|jpg|jpeg|png|bmp|pic" maxlength="1" onchange="change()" />
</div>
<div id="result" style="padding-top:5px;"> </div>
</form>
</body>
</html>
<script type="text/javascript">
$(function () {
var result = document.getElementById("result");
var input = document.getElementById("mainPicNum"); if (typeof FileReader === 'undefined') {
result.innerHTML = "抱歉,你的浏览器不支持 FileReader,请使用火狐浏览器,或其他兼容浏览器!";
input.setAttribute('disabled', 'disabled');
} $("#mainPicNum").MultiFile({
afterFileSelect: function (element, value, master_element) {
readFile.call(element);
},
afterFileRemove: function (element, value, master_element) {
$('img').each(function () {
if ($(this).data('src') && (element.files[0].name == $(this).data('src'))) {
$(this).remove();
}
});
}
}); function readFile() {
var file = this.files[0];
if (!/image\/\w+/.test(file.type)) {
alert("文件必须为图片!");
return false;
}
var reader = new FileReader();
reader.readAsDataURL(file);
reader.onload = function (e) {
result.innerHTML += '<img data-src="' + file.name + '" src="' + this.result + '" alt="" style=" height:100px; width:100px;"/>';
}
}
}); $('#mainPicNum').Html5Upload({
url: 'UploadImage.ashx?action=action',
perLoading: function (data, curindex) {
// console.log(data)
//$(".MultiFile-remove").css("display", "none");
//$(".MultiFile-title").css("display", "none");
},
perLoaded: function (curindex, data) {
//alert(data);
//alert("上传头像成功");
//var img = '<img src="/Images/foo.png" style="background-image: url(\'' + data + '\');" />';
// $('#hiddenImg').val(data);
// $(".js_pic").html(img);
}
}); </script>

一般处理程序如下:

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Web; namespace LLYY
{
/// <summary>
/// UploadImage 的摘要说明
/// </summary>
public class UploadImage : IHttpHandler
{ public void ProcessRequest(HttpContext context)
{
if (HttpContext.Current.Request.QueryString["action"] == "action")
{
uppic();
}
context.Response.ContentType = "text/plain";
} protected void uppic()
{
string fileTim = DateTime.Now.ToString("yyyMddHHmmssffff"); string pic = HttpContext.Current.Request.Form["pic"];
pic = HttpContext.Current.Server.UrlDecode(pic);
if (pic != null)
{
pic = pic.Split(',')[];
MemoryStream stream = new MemoryStream(Convert.FromBase64String(pic));
Bitmap image = new Bitmap(stream);
string fileurl = "/usercenter/uppic/";
string serverPath = HttpContext.Current.Server.MapPath(fileurl); if (Directory.Exists(serverPath) == false)//如果不存在就创建file文件夹
{
Directory.CreateDirectory(serverPath);
} string picNum=Guid.NewGuid().ToString("N");
string url = fileurl +picNum + ".png";
image.Save(HttpContext.Current.Server.MapPath(url));
HttpContext.Current.Response.Write(url);
} HttpContext.Current.Response.End();
} public bool IsReusable
{
get
{
return false;
}
}
}
}

今天是2018-8-7,我用这段代码作上传,发现还是有点小问题的,主要表现在抛出异常:字符数组或字符串长度无效!解决办法如下:

   protected void uppic()
{
string fileTim = DateTime.Now.ToString("yyyMddHHmmssffff"); string pic = HttpContext.Current.Request.Form["images"];
pic = HttpContext.Current.Server.UrlDecode(pic);
if (pic != null)
{
var imgData = pic.Split(',')[]; string dummyData = imgData.Trim().Replace("%", "").Replace(",", "").Replace(" ", "+");
if (dummyData.Length % > )
{
dummyData = dummyData.PadRight(dummyData.Length + - dummyData.Length % , '=');
}
byte[] byteArray = Convert.FromBase64String(dummyData); MemoryStream stream = new MemoryStream(byteArray);
Bitmap image = new Bitmap(stream);
string fileurl = "/usercenter/uppic/";
string serverPath = HttpContext.Current.Server.MapPath(fileurl); if (Directory.Exists(serverPath) == false)//如果不存在就创建file文件夹
{
Directory.CreateDirectory(serverPath);
} string picNum = Guid.NewGuid().ToString("N");
string url = fileurl + picNum + ".png";
image.Save(HttpContext.Current.Server.MapPath(url));
HttpContext.Current.Response.Write(url);
} HttpContext.Current.Response.End();
}

关于产生上述异常的原因,大家可参考:https://www.cnblogs.com/haoliansheng/p/4231846.html

直接复制粘贴即可

但是,我有一个疑问,希望大家能帮我解决。

我的疑问如下:

当网页第一次加载完成后,我们选择图片,执行如下操作:

第一步图示如下:

C# 异步上传图片案例

这时,图片已经上传到了指定路径。

紧接着,我们进行第二步,

第二步,点击 x ,把选择的图片去掉,然后再重新选择,图示如下:

C# 异步上传图片案例

结果后端程序不再执行了,也就是说程序仅仅只会在第一次执行。更改后,不执行,这样的异步上传肯定是不能满足工作需求的,但是,我个人能力有限,实在解决不了,请问各位大神,谁有好办法解决这个问题!

在此先说声谢谢!

如果谁能解决,请大度点,把您的优质代码贴在评论区!万分感谢!

@陈卧龙的博客

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