C#获取远程图片，需要Form用户名和密码的Authorization认证

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace Web.App_Code
{
    public partial class GetFlexImage : System.Web.UI.Page
    {
        public static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        
        protected void Page_Load(object sender, EventArgs e)
        {
            if(Request["IMG"]==null||string.IsNullOrEmpty(Request["IMG"]))
            {
                return;
            }
            try
            {
                string url = (Request["IMG"]).Replace("%","%25");
                HttpWebRequest WRequest;
                HttpWebResponse response = null;
                Uri uri = new Uri(url);
                CredentialCache cc = new CredentialCache();
                cc.Add(uri, "Basic", new NetworkCredential("epapi", "密码"));
                WRequest = (HttpWebRequest)HttpWebRequest.Create(uri);
                WRequest.Credentials = cc;
                WRequest.PreAuthenticate = true;
                WRequest.Method = "POST";
                WRequest.AllowWriteStreamBuffering = false;
                WRequest.SendChunked = false;
                WRequest.KeepAlive = true;
                WRequest.ContentLength = 0;

                //WRequest.SendChunked = true;
                //WRequest.ContentLength = 100000;
                WRequest.Timeout = 30000;
                WRequest.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(new ASCIIEncoding().GetBytes("epapi:epapiadmin")));
                try
                {
                    response = (HttpWebResponse)WRequest.GetResponse();
                }
                catch (WebException er)
                {
                    response = (HttpWebResponse)er.Response;
                }
                Bitmap myImage = new Bitmap(response.GetResponseStream());
                MemoryStream ms = new MemoryStream();
                myImage.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                Response.ClearContent();
                Response.ContentType = "image/gif";
                log.Debug("图片加载：" + (Request["IMG"]));
                Response.BinaryWrite(ms.ToArray());
            }
            catch(Exception err) {
                log.Debug("图片加载异常：" + Server.HtmlDecode(Request["IMG"]) + err.Message);
            }
        }
    }
}