有些朋友说 WebClient 不能保持 Session 和 Cookie，只有 HttpWebRequest 才能保持 Session。实际上我们只要重写 WebClient 的 GetWebRequest 方法就可以使 WebClient 保持 Session 和 Cookie。
下面是 HttpClient 类， 它继承自 WebClient，并重写了 GetWebRequest 方法。
/// <summary>
/// 支持 Session 和 Cookie 的 WebClient。
/// </summary>
public class HttpClient : WebClient
{
// Cookie 容器
private CookieContainer cookieContainer;
/// <summary>
/// 创建一个新的 WebClient 实例。
/// </summary>
public HttpClient()
{
this.cookieContainer = new CookieContainer();
}
/// <summary>
/// 创建一个新的 WebClient 实例。
/// </summary>
/// <param name="cookie">Cookie 容器</param>
public HttpClient(CookieContainer cookies)
{
this.cookieContainer = cookies;
}
/// <summary>
/// Cookie 容器
/// </summary>
public CookieContainer Cookies
{
get { return this.cookieContainer; }
set { this.cookieContainer = value; }
}
/// <summary>
/// 返回带有 Cookie 的 HttpWebRequest。
/// </summary>
/// <param name="address"></param>
/// <returns></returns>
protected override WebRequest GetWebRequest(Uri address)
{
WebRequest request = base.GetWebRequest(address);
if (request is HttpWebRequest)
{
HttpWebRequest httpRequest = request as HttpWebRequest;
httpRequest.CookieContainer = cookieContainer;
}
return request;
}
#region 封装了PostData, GetSrc 和 GetFile 方法
/// <summary>
/// 向指定的 URL POST 数据，并返回页面
/// </summary>
/// <param name="uriString">POST URL</param>
/// <param name="postString">POST 的 数据</param>
/// <param name="postStringEncoding">POST 数据的 CharSet</param>
/// <param name="dataEncoding">页面的 CharSet</param>
/// <returns>页面的源文件</returns>
public string PostData(string uriString, string postString, string postStringEncoding, string dataEncoding, out
string msg)
{
try
{
// 将 Post 字符串转换成字节数组
byte[] postData = Encoding.GetEncoding(postStringEncoding).GetBytes(postString);
this.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
// 上传数据，返回页面的字节数组
byte[] responseData = this.UploadData(uriString, "POST", postData);
// 将返回的将字节数组转换成字符串(HTML);
string srcString = Encoding.GetEncoding(dataEncoding).GetString(responseData);
srcString = srcString.Replace("\t", "");
srcString = srcString.Replace("\r", "");
srcString = srcString.Replace("\n", "");
msg = string.Empty;
return srcString;
}
catch (WebException we)
{
msg = we.Message;
return string.Empty;
}
}
/// <summary>
/// 获得指定 URL 的源文件
/// </summary>
/// <param name="uriString">页面 URL</param>
/// <param name="dataEncoding">页面的 CharSet</param>
/// <returns>页面的源文件</returns>
public string GetSrc(string uriString, string dataEncoding, out string msg)
{
try
{
// 返回页面的字节数组
byte[] responseData = this.DownloadData(uriString);
// 将返回的将字节数组转换成字符串(HTML);
string srcString = Encoding.GetEncoding(dataEncoding).GetString(responseData);
srcString = srcString.Replace("\t", "");
srcString = srcString.Replace("\r", "");
srcString = srcString.Replace("\n", "");
msg = string.Empty;
return srcString;
}
catch (WebException we)
{
msg = we.Message;
return string.Empty;
}
}
/// <summary>
/// 从指定的 URL 下载文件到本地
/// </summary>
/// <param name="uriString">文件 URL</param>
/// <param name="fileName">本地文件的完成路径</param>
/// <returns></returns>
public bool GetFile(string urlString, string fileName, out string msg)
{
try
{
this.DownloadFile(urlString, fileName);
msg = string.Empty;
return true;
}
catch (WebException we)
{
msg = we.Message;
return false;
}
}
#endregion
}
下面是 HttpClient 类， 它继承自 WebClient，并重写了 GetWebRequest 方法。
/// <summary>/// 支持 Session 和 Cookie 的 WebClient。/// </summary>public class HttpClient : WebClient { // Cookie 容器 private CookieContainer cookieContainer; /// <summary> /// 创建一个新的 WebClient 实例。 /// </summary> public HttpClient() { this.cookieContainer = new CookieContainer(); } /// <summary> /// 创建一个新的 WebClient 实例。 /// </summary> /// <param name="cookie">Cookie 容器</param> public HttpClient(CookieContainer cookies) { this.cookieContainer = cookies; } /// <summary> /// Cookie 容器 /// </summary> public CookieContainer Cookies { get { return this.cookieContainer; } set { this.cookieContainer = value; } } /// <summary> /// 返回带有 Cookie 的 HttpWebRequest。 /// </summary> /// <param name="address"></param> /// <returns></returns> protected override WebRequest GetWebRequest(Uri address) { WebRequest request = base.GetWebRequest(address); if (request is HttpWebRequest) { HttpWebRequest httpRequest = request as HttpWebRequest; httpRequest.CookieContainer = cookieContainer; } return request; } #region 封装了PostData, GetSrc 和 GetFile 方法 /// <summary> /// 向指定的 URL POST 数据，并返回页面 /// </summary> /// <param name="uriString">POST URL</param> /// <param name="postString">POST 的 数据</param> /// <param name="postStringEncoding">POST 数据的 CharSet</param> /// <param name="dataEncoding">页面的 CharSet</param> /// <returns>页面的源文件</returns> public string PostData(string uriString, string postString, string postStringEncoding, string dataEncoding, outstring msg)
{ try { // 将 Post 字符串转换成字节数组 byte[] postData = Encoding.GetEncoding(postStringEncoding).GetBytes(postString); this.Headers.Add("Content-Type", "application/x-www-form-urlencoded"); // 上传数据，返回页面的字节数组 byte[] responseData = this.UploadData(uriString, "POST", postData); // 将返回的将字节数组转换成字符串(HTML); string srcString = Encoding.GetEncoding(dataEncoding).GetString(responseData); srcString = srcString.Replace("\t", ""); srcString = srcString.Replace("\r", ""); srcString = srcString.Replace("\n", ""); msg = string.Empty; return srcString; } catch (WebException we) { msg = we.Message; return string.Empty; } } /// <summary> /// 获得指定 URL 的源文件 /// </summary> /// <param name="uriString">页面 URL</param> /// <param name="dataEncoding">页面的 CharSet</param> /// <returns>页面的源文件</returns> public string GetSrc(string uriString, string dataEncoding, out string msg) { try { // 返回页面的字节数组 byte[] responseData = this.DownloadData(uriString); // 将返回的将字节数组转换成字符串(HTML); string srcString = Encoding.GetEncoding(dataEncoding).GetString(responseData); srcString = srcString.Replace("\t", ""); srcString = srcString.Replace("\r", ""); srcString = srcString.Replace("\n", ""); msg = string.Empty; return srcString; } catch (WebException we) { msg = we.Message; return string.Empty; } } /// <summary> /// 从指定的 URL 下载文件到本地 /// </summary> /// <param name="uriString">文件 URL</param> /// <param name="fileName">本地文件的完成路径</param> /// <returns></returns> public bool GetFile(string urlString, string fileName, out string msg) { try { this.DownloadFile(urlString, fileName); msg = string.Empty; return true; } catch (WebException we) { msg = we.Message; return false; } } #endregion}
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