C#中实现POST的方法很多，常用的是WebBrowser、WebClient、HttpWebRequest和HttpWebResponse。
1、WebBrowser基本是在DocumentCompleted中分析HtmlDocument ；
2、WebClient是对HttpWebRequest和HttpWebResponse的封装，用起来更方便，但是灵活性还是不及HttpWebRequest和HttpWebResponse；
3、HttpWebRequest和HttpWebResponse更底层，灵活度更好，不过代码更多，我做了一个简单的封装，将GET改成分段读取，并加入代理、进度条和错误重试处理。代码如下：
using System; using System.IO; using System.Net; using System.Text; namespace Van.Base { public class HttpHelper { #region 委托 事件 public delegate void dgtProgValueChanged( long Value); /// <summary> /// 进度改变事件 /// </summary> public event dgtProgValueChanged OnProgValueChanged; #endregion #region 属性 /// <summary> /// 代理 /// </summary> public WebProxy Proxy { get; set; } /// <summary> /// Cookie /// </summary> public CookieContainer UserCookie { get; set; } /// <summary> /// 重试次数 /// </summary> public int IAfreshTime { get; set; } /// <summary> /// 错误次数 /// </summary> public int IErrorTime { get; private set; } long m_ProgValue = 0; /// <summary> /// 当前读取字节 /// </summary> public long ProgValue { get { return m_ProgValue; } private set { m_ProgValue = value; if (OnProgValueChanged != null) { OnProgValueChanged(value); } } } /// <summary> /// 待读取最大字节 /// </summary> public long ProgMaximum { get; private set; } #endregion #region 方法 #region Get /// <summary> /// 获取HTML /// </summary> /// <param name="URL"> 地址 </param> /// <param name="Accept"> Accept请求头 </param> /// <returns> Html代码 </returns> public string GetHTML( string URL, string Accept) { return GetHTML(URL, Accept, System.Text.Encoding.UTF8); } /// <summary> /// 获取HTML /// </summary> /// <param name="URL"> 地址 </param> /// <param name="Accept"> Accept请求头 </param> /// <param name="encoding"> 字符编码 </param> /// <returns> Html代码 </returns> public string GetHTML( string URL, string Accept, Encoding encoding) { return GetHTML(URL, Accept, encoding, 1024); } /// <summary> /// 获取HTML /// </summary> /// <param name="URL"> 地址 </param> /// <param name="Accept"> Accept请求头 </param> /// <param name="encoding"> 字符编码 </param> /// <param name="bufflen"> 数据包大小 </param> /// <returns> Html代码 </returns> public string GetHTML( string URL, string Accept, Encoding encoding, int bufflen) { IErrorTime = 0; return _GetHTML(URL, Accept, encoding, bufflen); } /// <summary> /// 获取HTML /// </summary> /// <param name="URL"> 地址 </param> /// <param name="Accept"> Accept请求头 </param> /// <param name="encoding"> 字符编码 </param> /// <param name="bufflen"> 数据包大小 </param> /// <returns> Html代码 </returns> private string _GetHTML( string URL, string Accept, Encoding encoding, int bufflen) { try { HttpWebRequest MyRequest = (HttpWebRequest)HttpWebRequest.Create(URL); MyRequest.Proxy = Proxy; MyRequest.Accept = Accept; if (UserCookie == null) { UserCookie = new CookieContainer(); } MyRequest.CookieContainer = UserCookie; HttpWebResponse MyResponse = (HttpWebResponse)MyRequest.GetResponse(); return _GetHTML(MyResponse, encoding, bufflen); } catch (Exception erro) { if (erro.Message.Contains( " 连接 ") && IAfreshTime - IErrorTime > 0) { IErrorTime++; return _GetHTML(URL, Accept, encoding, bufflen); } throw; } } /// <summary> /// 获取HTML /// </summary> /// <param name="MyResponse"></param> /// <param name="encoding"> 字符编码 </param> /// <param name="bufflen"> 数据包大小 </param> /// <returns></returns> private string _GetHTML(HttpWebResponse MyResponse, Encoding encoding, int bufflen) { using (Stream MyStream = MyResponse.GetResponseStream()) {
ProgMaximum = MyResponse.ContentLength; string result = null; long totalDownloadedByte = 0; byte[] by = new byte[bufflen]; int osize = MyStream.Read(by, 0, by.Length); while (osize > 0) { totalDownloadedByte = osize + totalDownloadedByte; result += encoding.GetString(by, 0, osize); ProgValue = totalDownloadedByte; osize = MyStream.Read(by, 0, by.Length); } MyStream.Close(); return result; } } #endregion #region GetImg public System.Drawing.Bitmap Getimg( string URL, string Accept) { return _GetBit(URL, Accept); } /// <summary> /// 获取HTML /// </summary> /// <param name="URL"> 地址 </param> /// <param name="Accept"> Accept请求头 </param> /// <returns> Html代码 </returns> private System.Drawing.Bitmap _GetBit( string URL, string Accept) { HttpWebRequest MyRequest = (HttpWebRequest)HttpWebRequest.Create(URL); MyRequest.Proxy = Proxy; MyRequest.Accept = Accept; if (UserCookie == null) { UserCookie = new CookieContainer(); } MyRequest.CookieContainer = UserCookie; HttpWebResponse MyResponse = (HttpWebResponse)MyRequest.GetResponse(); return _GetBit(MyResponse); } /// <summary> /// 获取图像 /// </summary> /// <param name="MyResponse"></param> /// <returns></returns> private System.Drawing.Bitmap _GetBit(HttpWebResponse MyResponse) { using (Stream MyStream = MyResponse.GetResponseStream()) { return new System.Drawing.Bitmap(MyStream); } } #endregion #region Post /// <summary> /// 回发(字符编码默认UTF-8) /// </summary> /// <param name="URL"> 回发地址 </param> /// <param name="PostData"> 参数 </param> /// <returns> Html代码 </returns> public string PostPage( string URL, string PostData) { return PostPage(URL, PostData, System.Text.Encoding.UTF8); } /// <summary> /// 回发 /// </summary> /// <param name="URL"> 回发地址 </param> /// <param name="PostData"> 参数 </param> /// <param name="encoding"> 字符编码 </param> /// <returns> Html代码 </returns> public string PostPage( string URL, string PostData, Encoding encoding) { return PostPage(URL, PostData, encoding, null); } /// <summary> /// 回发 /// </summary> /// <param name="URL"> 回发地址 </param> /// <param name="PostData"> 参数 </param> /// <param name="encoding"> 字符编码 </param> /// <returns> Html代码 </returns> public string PostPage( string URL, string PostData, Encoding encoding, string ContentType) { IErrorTime = 0; return _PostPage(URL, PostData, encoding, ContentType); } /// <summary> /// 回发 /// </summary> /// <param name="URL"> 回发地址 </param> /// <param name="PostData"> 参数 </param> /// <param name="encoding"> 字符编码 </param> /// <returns> Html代码 </returns> private string _PostPage( string URL, string PostData, Encoding encoding, string ContentType) { try { if (ContentType== null) { ContentType = " application/x-www-form-urlencoded "; } HttpWebRequest MyRequest = (HttpWebRequest)HttpWebRequest.Create(URL); MyRequest.Proxy = Proxy; if (UserCookie == null) { UserCookie = new CookieContainer(); } MyRequest.CookieContainer = UserCookie; MyRequest.Method = " POST "; MyRequest.ContentType = ContentType; byte[] b = encoding.GetBytes(PostData); MyRequest.ContentLength = b.Length; using (System.IO.Stream sw = MyRequest.GetRequestStream()) { try { sw.Write(b, 0, b.Length); } catch { } } HttpWebResponse MyResponse = (HttpWebResponse)MyRequest.GetResponse(); return _GetHTML(MyResponse, encoding, 1024); } catch (Exception erro) { if (erro.Message.Contains( " 连接 ") && IAfreshTime - IErrorTime > 0) { IErrorTime++; return _PostPage(URL, PostData, encoding, ContentType); } throw; } } #endregion #endregion } }
调用便很方便了，如下：
string strProxyAdd = " www.Proxyxxxx.com ", UserName = " XXXX ",PassWord = " XXX "; int port = 8080; HttpHelper http = new HttpHelper(); http.Proxy = new WebProxy(); // 设置代理 this.http.Proxy.Address = new Uri( string.Format( " http://{0}:{1} ", strProxyAdd,port)); // 设置代理服务器地址和端口 this.http.Proxy.Credentials = new NetworkCredential(UserName, PassWord); // 设置代理用户名密码 // http.Proxy = null; // 清空代理
var strPHtml = http.PostPage( " www.xxxx.com ", " User=ABCD&Pwd=DEF "); // 向www.xxxx.com POST数据User=ABCD&Pwd=DEF
var strHtml = http.GetHTML( " www.xxxx.com ", " */* ", Encoding.UTF8, 20480); // 从www.xxxx.com获取HTML数据，并用UTF8进行编码
由于Cookie在一个实例中是共用的，在一些场景下可以先POST登录后再GET需要登录才能进入的页面信息。