[c#] HttpWebRequest簡單實用封裝應用類

   很多時候我們要用HttpWebRequest組件模擬http協議發送web請求，封裝一個請求類看起來就很有必要了。要很好的封裝一個這樣的類，要考慮很多因素，比如通用性和異常處理，甚至還可以是繼承性。當然，我下面要說的是一個靜態類，繼承什么的就算了，簡單封裝一下能用就行，呵呵，太懶了。

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;

namespace Uu102
{
    /// <summary>
    ///http協議模擬請求類
    ///主要考慮請求后的具體結果
    ///此類出自 uu102.com，請尊重原作者，轉載請加上此鏈接
    /// </summary>
    class HttpHelper
    {
        /// <summary>
        /// 請求並發限制數目
        /// </summary>
       private static int DefaultConnectionLimit=1;
       private const string Accept = "*/*";
       private const string UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022)";
       private const string ContentType = "application/x-www-form-urlencoded";
       
        /// <summary>
        /// 發送資源請求。返回請求到的響應文本
        /// 之所以看到這么多形參，只是本人的水平很菜的體現^.^ 
        /// 注意，這個類並沒有處理https加密請求
        /// </summary>
        /// <param name="url">發送請求的url地址</param>
        /// <param name="postString"></param>
        /// <param name="IsPost"></param>
        /// <param name="cookieContainer"></param>
        /// <param name="referer"></param>
        /// <param name="encoding"></param>
        /// <returns></returns>
        public static string GetHtml(string url, string postString, bool IsPost, CookieContainer cookieContainer, string referer, Encoding encoding)
        {
            string html = string.Empty;
            ServicePointManager.Expect100Continue = false;
            ServicePointManager.DefaultConnectionLimit = DefaultConnectionLimit;//設置並發連接數限制上額
            DefaultConnectionLimit++;
            if (string.IsNullOrEmpty(postString)) IsPost = false;
            HttpWebRequest httpWebRequest = null;
           
            HttpWebResponse httpWebResponse = null;
            try
            {
                httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);//創建連接請求
                httpWebRequest.Method = IsPost ? "POST" : "GET";
                if (cookieContainer != null) httpWebRequest.CookieContainer = cookieContainer;
                httpWebRequest.AllowAutoRedirect = true;//【注意】這里有個時候在特殊情況下要設置為否，否則會造成cookie丟失
                httpWebRequest.ContentType = ContentType;
                httpWebRequest.Accept = Accept;
                httpWebRequest.UserAgent = UserAgent;
                if (!string.IsNullOrEmpty(referer)) httpWebRequest.Referer = referer;
                if (IsPost)  //如果是Post遞交數據，則寫入傳的字符串數據
                {
                    byte[] byteRequest = Encoding.Default.GetBytes(postString);
                    httpWebRequest.ContentLength = byteRequest.Length;
                    Stream stream = httpWebRequest.GetRequestStream();
                    stream.Write(byteRequest, 0, byteRequest.Length);
                    stream.Close();
                }

                httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();//開始獲取響應流
                Stream responseStream = httpWebResponse.GetResponseStream();
                StreamReader streamReader = new StreamReader(responseStream, encoding);
                html = streamReader.ReadToEnd();//注意這里是直接將所有的字節從頭讀到尾，也可以一行一行的控制，節省時間
                streamReader.Close();
                responseStream.Close();
                httpWebRequest.Abort();

                foreach (Cookie cookie in httpWebResponse.Cookies) //獲取cookie
                {
                    cookieContainer.Add(cookie);
                }

                httpWebResponse.Close();
                //到這里為止，所有的對象都要釋放掉，以免內存像滾雪球一樣
                return html;
            }
            catch 
            {
                DefaultConnectionLimit--;
               //我這里就沒做任何處理了，這里最好還是處理一下
                return null;
            }
            
        }
        #region 重載方法
        public static string GetHtml(string url, string postString, CookieContainer cookieContainer, string referer)
        {
            return GetHtml(url, postString, true, cookieContainer, referer, Encoding.UTF8);
        }
        public static string GetHtml(string url, string postString, CookieContainer cookieContainer)
        {
            return GetHtml(url, postString, true, cookieContainer, url, Encoding.UTF8);
        }
        public static string GetHtml(string url, CookieContainer cookieContainer, string referer)
        {
            return GetHtml(url, "", false, cookieContainer, referer, Encoding.UTF8);
        }
        public static string GetHtml(string url, CookieContainer cookieContainer)
        {
            return GetHtml(url, "", false, cookieContainer, url, Encoding.UTF8);
        }
        public static string GetHtml(string url)
        {
            return GetHtml(url, "", true, null, url, Encoding.UTF8);
        }
        #endregion
        /// <summary>
        /// 這個方法主要用來獲取非文本的html響應正文
        /// </summary>
        /// <param name="url"></param>
        /// <param name="cookieContainer"></param>
        /// <returns></returns>
        public static Stream GetStream(string url,CookieContainer cookieContainer)
        {
            HttpWebRequest httpWebRequest = null;
            HttpWebResponse httpWebResponse = null;

            try
            {

                httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);
                httpWebRequest.CookieContainer = cookieContainer;
                httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                Stream responseStream = httpWebResponse.GetResponseStream();
                return responseStream;
            }
            catch
            {
                if (httpWebRequest != null)
                {
                    httpWebRequest.Abort();
                } if (httpWebResponse != null)
                {
                    httpWebResponse.Close();
                }
                return null;
            }
        }

    }
}

 

代碼太簡單解釋都免了吧？要強調的一點，上面的封裝類還沒有處理https這樣的加密連接，以及返回的status和異常，如果是自己調試，最好是將try這個功能注釋掉，免得看了半天都不知道哪出了問題。
以上的功能雖然能適合絕大部分請求，但是仍有一些請客不適合，比如當模擬上傳文件等等的情況就不適用。

下次我們就聊聊加密請求，以及模擬上傳文件的方法吧！

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