.net如何获取网页内容

.net中如何获取网页内容，下面给出C#版本的函数，关键代码如下：

1、引入namespace

using System.Net;
using System.IO;
using System.Text;

2、函数代码：

        /// <summary>
        /// 返回URL内容,带POST数据提交
        /// </summary>
        /// <param name="url"></param>
        /// <param name="data"></param>
        /// <param name="method">GET/POST(默认)</param>
        /// <param name="dataEncoding">编码方式(默认utf-8)</param>
        /// <param name="timeout">超时时间（以毫秒为单位）</param>
        /// <returns></returns>
        public static string HttpRequest(string url, string data, string method, string dataEncoding, int timeout)
        {
            string res = string.Empty;
            if (string.IsNullOrEmpty(dataEncoding)) dataEncoding = "utf-8";
            Encoding encoding = Encoding.GetEncoding(dataEncoding);

            //请求
            WebRequest webRequest = null;
            Stream postStream = null;

            //响应
            WebResponse webResponse = null;
            StreamReader streamReader = null;

            try
            {
                if (method == "GET")
                {
                    url = url + '?' + data;
                }
                //请求
                webRequest = WebRequest.Create(url);
                webRequest.Method = string.IsNullOrEmpty(method) ? "POST" : method;
                webRequest.Timeout = timeout;

                if (method == "POST")
                {
                    byte[] postData = encoding.GetBytes(data);
                    webRequest.ContentLength = postData.Length;
                    postStream = webRequest.GetRequestStream();
                    postStream.Write(postData, 0, postData.Length);
                }
                //响应
                webResponse = webRequest.GetResponse();
                streamReader = new StreamReader(webResponse.GetResponseStream(), encoding);
                res = streamReader.ReadToEnd();
            }
            catch (WebException ex)
            {
                using (HttpWebResponse response = (HttpWebResponse)ex.Response)
                {
                    using (Stream responseStream = response.GetResponseStream())
                    {
                        res = new StreamReader(responseStream).ReadToEnd();
                    }
                }
            }
            catch (Exception)
            {
            }
            finally
            {
                if (postStream != null)
                {
                    postStream.Close();
                }
                if (streamReader != null)
                {
                    streamReader.Close();
                }
                if (webResponse != null)
                {
                    webResponse.Close();
                }
            }
            return res;
        }

3、调用示例：

Get：HttpRequest("http://test.com/request.aspx","user=aa&pwd=bbb","GET",null,30)

关键类：Encoding,WebRequest,Stream,WebResponse,StreamReader