Http 辅助类

using System;
using System.Drawing;
using System.IO;
using System.Net;
using System.Net.Cache;
using System.Text;

namespace ePlatform.Processor
{
    /// <summary>
    /// Http处理
    /// </summary>
    public static class Http
    {
        /// <summary>
        /// 创建访问URL的Response
        /// </summary>
        /// <param name="uri"></param>
        /// <param name="mycookies"></param>
        /// <returns></returns>
        public static HttpWebResponse GetWebResponse(string uri, ref CookieCollection mycookies)
        {
            try
            {
                //请求
                var req = HttpWebRequest.Create(uri) as HttpWebRequest;
                var cookies = new CookieContainer();

                req.KeepAlive = true;
                req.AllowAutoRedirect = true;
                req.AllowWriteStreamBuffering = true;
                req.Credentials = CredentialCache.DefaultCredentials;
                req.Referer = "http://www.lanxe.net/";
                req.Timeout = 20000;
                req.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E)";
                req.CookieContainer = cookies;

                //加入额外的Cookie
                if (mycookies != null)
                {
                    foreach (Cookie item in mycookies)
                    {
                        cookies.Add(item);
                    }
                }

                //回应
                var res = req.GetResponse() as HttpWebResponse;
                mycookies = cookies.GetCookies(req.RequestUri);
                res.Cookies = mycookies;

                return res;
            }
            catch
            {
                return null;
            }
        }

        /// <summary>
        /// 向网站Post数据
        /// </summary>
        /// <param name="uri"></param>
        /// <param name="mycookies"></param>
        /// <param name="encoding"></param>
        /// <param name="data"></param>
        /// <returns></returns>
        public static string PostData(string uri, ref CookieCollection mycookies, string encoding, string data)
        {
            var encode = getEncoding(encoding);
            var datas = encode.GetBytes(data);
            var length = datas.Length;

            try
            {
                //请求
                var req = HttpWebRequest.Create(uri) as HttpWebRequest;
                var cookies = new CookieContainer();
                var cache = new RequestCachePolicy(RequestCacheLevel.NoCacheNoStore);

                req.KeepAlive = true;
                req.AllowAutoRedirect = true;
                req.AllowWriteStreamBuffering = true;
                req.Credentials = CredentialCache.DefaultCredentials;
                req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";
                req.Accept = "*/*";
                req.Referer = "http://translate.google.com.hk/";
                req.Timeout = 20000;
                req.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E)";
                req.CachePolicy = cache;
                req.Method = "POST";
                req.ContentLength = length;
                req.CookieContainer = cookies;

                //加入额外的Cookie
                if (mycookies != null)
                {
                    foreach (Cookie item in mycookies)
                    {
                        cookies.Add(item);
                    }
                }

                //发送内容
                var stream = req.GetRequestStream();
                stream.Write(datas, 0, length);
                stream.Close();

                //获取返回的数据
                var res = (HttpWebResponse)req.GetResponse();
                mycookies = cookies.GetCookies(req.RequestUri);
                return getHtml(res, encode);
            }
            catch
            {
                return null;
            }
        }

        /// <summary>
        /// 获取网页源代码
        /// </summary>
        /// <param name="uri"></param>
        /// <param name="encodeName"></param>
        /// <param name="outCookies"></param>
        /// <returns></returns>
        public static string GetHtml(string uri, string encodeName, ref CookieCollection mycookies)
        {
            var response = GetWebResponse(uri, ref mycookies);
            if (response == null)
            {
                return null;
            }
            try
            {
                var encode = getEncoding(encodeName);
                return getHtml(response, encode);
            }
            catch
            {
                return null;
            }
        }

        /// <summary>
        /// 获取网页流图像
        /// </summary>
        /// <param name="uri"></param>
        /// <param name="mycookies"></param>
        /// <param name="length"></param>
        /// <returns></returns>
        public static Image GetImage(string uri, ref CookieCollection mycookies, out long length)
        {
            length = 0;
            var res = GetWebResponse(uri, ref mycookies);
            if (res == null)
            {
                return null;
            }
            try
            {
                length = res.ContentLength;
                Stream stream = res.GetResponseStream();
                return Image.FromStream(stream, true);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 根据名称获取网页编码格式
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        static Encoding getEncoding(string name)
        {
            if (string.IsNullOrEmpty(name))
            {
                return Encoding.UTF8;
            }
            else if (name.ToLower() == "default")
            {
                return Encoding.Default;
            }
            else
            {
                return Encoding.GetEncoding(name);
            }
        }

        /// <summary>
        /// 从Response中获取HTML内容
        /// </summary>
        /// <param name="res"></param>
        /// <param name="encode"></param>
        /// <returns></returns>
        static string getHtml(HttpWebResponse res, Encoding encode)
        {
            var outs = new StringBuilder();
            var stream = res.GetResponseStream();
            var reader = new StreamReader(stream, encode);

            // 每次读取1024
            var buffer = new char[1024];
            var count = reader.Read(buffer, 0, 1024);
            while (count > 0)
            {
                outs.Append(new String(buffer, 0, count));
                count = reader.Read(buffer, 0, 1024);
            }

            // 读取完毕
            reader.Close();
            stream.Close();

            return outs.ToString();
        }
    }
}