C#获取网页的HTML码、下载网站图片 get post

/// <summary>
/// 获取网页的HTML码
/// </summary>
/// <param name="url">链接地址</param>
/// <param name="encoding">编码类型</param>
/// <returns></returns>
public static string GetHtmlStr(string url, string encoding)
{
    string htmlStr = "";
    if (!String.IsNullOrEmpty(url))
    {
        WebRequest request = WebRequest.Create(url);            //实例化WebRequest对象
        WebResponse response = request.GetResponse();           //创建WebResponse对象
        Stream datastream = response.GetResponseStream();       //创建流对象
        Encoding ec = Encoding.Default;
        if (encoding == "UTF8")
        {
            ec = Encoding.UTF8;
        }
        else if (encoding == "Default")
        {
            ec = Encoding.Default;
        }
        StreamReader reader = new StreamReader(datastream, ec);
        htmlStr = reader.ReadToEnd();                           //读取数据
        reader.Close();
        datastream.Close();
        response.Close();
    }
    return htmlStr;
}

/// <summary>
/// 下载网站图片
/// </summary>
/// <param name="picUrl"></param>
/// <returns></returns>
public string SaveAsWebImg(string picUrl)
{
    string result = "";
    string path = AppDomain.CurrentDomain.SetupInformation.ApplicationBase + @"/File/";  //目录
    try
    {
        if (!String.IsNullOrEmpty(picUrl))
        {
            Random rd = new Random();
            DateTime nowTime = DateTime.Now;
            string fileName = nowTime.Month.ToString() + nowTime.Day.ToString() + nowTime.Hour.ToString() + nowTime.Minute.ToString() + nowTime.Second.ToString() + rd.Next(, ) + ".jpeg";
            WebClient webClient = new WebClient();
            webClient.DownloadFile(picUrl, path + fileName);
            result = fileName;
        }
    }
    catch { }
    return result;
}