C#替换下载远程图片

/// <summary>
/// 替换下载远程图片及入库操作
/// </summary>
/// <param name="strInput">内容</param>
/// <returns>返回string类型;替换后的内容</returns>
public static string ReplaceRemoteUrl(string strInput)
{
string tempFilePath="";
string outStr;
outStr = strInput;

//获取远程图片url集合
string _pattern = @"(http|https|ftp|rtsp|mms):(\/\/|\\\\){1}((([\w-])+[.]){1,}(net|com|cn|org|cc|tv|[0-9]{1,3}))([^\?\s]*\/)(([^\?\s])+[.]{1}(gif|jpg|png|bmp))";
MatchCollection found =null;
RegexOptions TheOptions;
TheOptions = RegexOptions.Singleline | RegexOptions.IgnoreCase;
Regex r = new Regex(_pattern,TheOptions);
found = r.Matches(strInput);

foreach (Match m in found)
{
tempFilePath="";
if(m.Value.Length>0)
{
tempFilePath = GetRemoteImage(m.Value);
//如果下载成功
if(tempFilePath.Length>0)
{
outStr = outStr.Replace(m.Value,tempFilePath);
}
}
}

return outStr;
}
/// <summary>
/// 下载远程图片
/// </summary>
/// <param name="strUrl">将要下载的图片地址</param>
/// <returns>返回string类型;图片的本地地址</returns>
private static string GetRemoteImage(string strUrl)
{
try
{
//硬盘路径
string PathStr = System.Configuration.ConfigurationSettings.AppSettings["MoviePath"];
//url路径
string dPathStr = System.Configuration.ConfigurationSettings.AppSettings["MovieWebPath"];

string fileExt = System.IO.Path.GetExtension(strUrl);
Random ro=new Random((int)DateTime.Now.Ticks);
Random ro2 = new Random(Guid.NewGuid().GetHashCode());
string filePath = @"Upload\Image\"+ DateTime.Now.ToString("yyyy") + @"\" + DateTime.Now.ToString("MMdd") + @"\" + DateTime.Now.ToString("yyyyMMddHHmmss") + ro.Next(1000) + fileExt;

string tempFolder = System.IO.Path.GetDirectoryName(PathStr + filePath);
if( !System.IO.Directory.Exists( tempFolder ) )
{
System.IO.Directory.CreateDirectory(tempFolder);
}

WebClient wc = new WebClient();
wc.DownloadFile(strUrl,PathStr + filePath);
wc.Dispose();

filePath = dPathStr + filePath;
return filePath;
}
catch(Exception err)
{
System.Web.HttpContext.Current.Response.Write("<script language='JavaScript' type='text/JavaScript'>alert('获取远程图片出错!原因如下:\\n"+ err.Message +"');</script>\n");
//HttpContext.Current.Response.Write(Functions.ShowErr("获取远程图片出错!原因如下:\\n" + ,1));
//HttpContext.Current.Response.End();
return "";
}
}