C#实现下载网页HTML源码的方法

public static class DownLoad_HTML{private static int FailCount = 0; //记录下载失败的次数public static string GetHtml(string url) //传入要下载的网址{string str = string.Empty;try{System.Net.WebRequest request = System.Net.WebRequest.Create(url);request.Timeout = 10000; //下载超时时间request.Headers.Set("Pragma", "no-cache");System.Net.WebResponse response = request.GetResponse();System.IO.Stream streamReceive = response.GetResponseStream();Encoding encoding = Encoding.GetEncoding("gb2312");//utf-8 网页文字编码System.IO.StreamReader streamReader = new System.IO.StreamReader(streamReceive, encoding);str = streamReader.ReadToEnd();streamReader.Close();}catch (Exception ex){FailCount++;if (FailCount > 5){var result = System.Windows.Forms.MessageBox.Show("已下载失败" + FailCount + "次，是否要继续尝试？" + Environment.NewLine + ex.ToString(), "数据下载异常", System.Windows.Forms.MessageBoxButtons.YesNo, System.Windows.Forms.MessageBoxIcon.Error);if (result == System.Windows.Forms.DialogResult.Yes){str = GetHtml(url);}else{System.Windows.Forms.MessageBox.Show("下载HTML失败" + Environment.NewLine + ex.ToString(), "下载HTML失败", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Error);throw ex;}}else{str = GetHtml(url);}}FailCount = 0; //如果能执行到这一步就表示下载终于成功了return str;}