使用C#获取远程图片 Form用户名与密码Authorization认证的实现

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);
            }
        }
    }
}