网络蜘蛛或爬虫需要能够下载网页、图片（流）以及登录的Cookies等信息，以下的C#代码是比较实用的核心程序。
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.IO.Compression;
using System.Xml;
using System.Web;
using System.Collections;
using System.Runtime.InteropServices;
using System.Net;
using System.Net.Security;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
namespace Common
{
/// <summary>
/// 准备POST
/// </summary>
/// <param name="httpRequest"></param>
public delegate void OnGetPostReady(HttpWebRequest httpRequest);
/// <summary>
/// 准备取回应
/// </summary>
/// <param name="httpRequest"></param>
public delegate void OnGetResponseReady(HttpWebRequest httpRequest);
public class HttpWebHelper
{
protected HttpWebRequest httpRequest;
protected HttpWebResponse httpResponse;
protected CookieContainer cookieContainer;
protected CredentialCache credentialCache;
protected bool certificatedMode = false;
protected string certFilepath = string.Empty;
public OnGetPostReady OnGetPostReadyHandler = null;
public OnGetPostReady OnGetResponseReadyHandler = null;
protected readonly int DEFAULT_BUFFER_SIZE = 4096;
public WebProxy webProxySrv = null;
private static readonly int MyConnectionLimit = 300;
public bool CheckGotoRecv
{
get;
set;
}
public bool DoBetIsGotoRecv
{
get;
set;
}
public bool LastAccessError
{
private set;
get;
}
/// <summary>
/// 当前自动转向后的url
/// </summary>
public string CurrentUrl
{
private set;
get;
}
public string CurrentLocation
{
private set;
get;
}
public string CurSetCookie
{
set;
get;
}
public string CurSetCookie2
{
set;
get;
}
/// <summary>
/// 默认构造器
/// </summary>
public HttpWebHelper()
{
this.cookieContainer = new CookieContainer();
ServicePointManager.DefaultConnectionLimit = MyConnectionLimit;
ServicePointManager.Expect100Continue = false;
ServicePointManager.MaxServicePointIdleTime = 10000;
}
/// <summary>
/// 代理參數構造器
/// </summary>
/// <param name="wp"></param>
public HttpWebHelper(WebProxy wp) : this()
{
this.webProxySrv = wp;
}
/// <summary>
/// 需要基本认证的构造器
/// </summary>
/// <param name="cred"></param>
public HttpWebHelper(bool cred)
: this()
{
this.certificatedMode = cred;
}
public HttpWebHelper(bool cred, WebProxy wp)
: this()
{
this.certificatedMode = cred;
this.webProxySrv = wp;
}
/// <summary>
/// 基本认证和证书,refer页面
/// </summary>
/// <param name="cred"></param>
/// <param name="certFilepath"></param>
public HttpWebHelper(bool cred, string certFilepath)
: this(cred)
{
this.certFilepath = certFilepath;
}
public HttpWebHelper(bool cred, WebProxy wp, string certFilepath)
: this(cred, wp)
{
this.certFilepath = certFilepath;
}
/// <summary>
/// 提供批量用户名和密码的构造器
/// </summary>
/// <param name="uri"></param>
/// <param name="method"></param>
/// <param name="username"></param>
/// <param name="password"></param>
public HttpWebHelper(string uri, string method, string username, string password)
: this(true)
{
this.credentialCache = new CredentialCache();
this.credentialCache.Add(new Uri(uri), method, new NetworkCredential(username, password));
}
/// <summary>
/// 安全询问回调函数,直接同意
/// </summary>
/// <param name="sender"></param>
/// <param name="certificate"></param>
/// <param name="chain"></param>
/// <param name="errors"></param>
/// <returns></returns>
public bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
{
return true;
}
private void SetHttpRequestOptions_Accept(string url, string method, CookieCollection cc, string referUrl, bool nocache, DecompressionMethods dm, string httpAccept)
{
this.SetHttpRequestOptions(url, method, cc, referUrl, nocache, dm);
this.httpRequest.Accept = httpAccept;
}
/// <summary>
/// 设置HttpWebRequest对象
/// </summary>
/// <param name="url"></param>
/// <param name="method"></param>
/// <param name="cc"></param>
/// <param name="referUrl"></param>
/// <param name="nocache"></param>
/// <param name="dm"></param>
private void SetHttpRequestOptions(string url, string method, CookieCollection cc, string referUrl, bool nocache, DecompressionMethods dm)
{
httpRequest = (HttpWebRequest)HttpWebRequest.Create(url);
httpRequest.UnsafeAuthenticatedConnectionSharing = true;
httpRequest.ServicePoint.ConnectionLimit = MyConnectionLimit;
if (null != this.webProxySrv) httpRequest.Proxy = this.webProxySrv;
if (this.certificatedMode && url.ToLower().Substring(0, 5).Equals("https"))
{
ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(CheckValidationResult);
if (null == this.credentialCache)
httpRequest.UseDefaultCredentials = true;
else
httpRequest.Credentials = this.credentialCache;
if (!string.IsNullOrEmpty(this.certFilepath))
httpRequest.ClientCertificates.Add(X509Certificate.CreateFromCertFile(this.certFilepath));
}
httpRequest.CookieContainer = this.cookieContainer;
if (!string.IsNullOrEmpty(referUrl)) httpRequest.Referer = referUrl;
httpRequest.AutomaticDecompression = dm;
httpRequest.ServicePoint.Expect100Continue = false;
httpRequest.ServicePoint.UseNagleAlgorithm = false;
httpRequest.ContentType = "application/x-www-form-urlencoded";
// httpRequest.Accept = "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, */*";
// httpRequest.AllowWriteStreamBuffering = true; 默认值就是true
// httpRequest.AllowAutoRedirect = true; 默认值就是true
httpRequest.Method = method;
httpRequest.Timeout = ApplicationConfig.HTTP_REQUEST_TIMEOUT;
// 讀寫超時
//httpRequest.ReadWriteTimeout = ApplicationConfig.HTTP_REQUEST_TIMEOUT;
// httpRequest.MaximumAutomaticRedirections = 50; 默认值就是50
httpRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
httpRequest.Headers.Add("Accept-Language", "zh-cn");
httpRequest.Headers.Add("UA-CPU", "x86");
//httpRequest.Headers.Add("Accept-Encoding", "gzip, deflate");
if (nocache)
{
httpRequest.Headers.Add("Cache-Control", "no-cache");
//httpRequest.Headers.Add("Pragma", "no-cache");
}
if (null != cc) httpRequest.CookieContainer.Add(cc);
// 回调发起请求前事件
if(null != this.OnGetPostReadyHandler)
{
try
{
this.OnGetPostReadyHandler(this.httpRequest);
//BaseDebug.DebugPrint("KeepAlive = " + this.httpRequest.KeepAlive.ToString());
}
catch (System.Exception ex)
{
this.LastAccessError = true;
BaseDebug.DebugPrint(ex.ToString());
}
}
}
private void SetHttpRequestOptions(string url, string method, CookieCollection cc, string referUrl, string httpAccept)
{
this.SetHttpRequestOptions_Accept(url, method, cc, referUrl, false, DecompressionMethods.GZip | DecompressionMethods.Deflate, httpAccept);
}
/// <summary>
/// 重新设置某些成员
/// </summary>
private void ManualResetMember()
{
this.cookieContainer = httpRequest.CookieContainer;
this.CurrentUrl = httpRequest.Address.OriginalString;
this.CurrentLocation = httpResponse.Headers["Location"];
}
public MemoryStream GetMemoryStream(string url, string method, CookieCollection cc, string referUrl, string httpAccept)
{
MemoryStream ms = new MemoryStream();
try
{
this.SetHttpRequestOptions(url, method, cc, referUrl, "*/*");
this.httpRequest.Accept = httpAccept;
this.httpResponse = (HttpWebResponse)httpRequest.GetResponse();
// 是否收到响应
if (!this.httpRequest.HaveResponse)
{
this.httpResponse.Close();
this.httpRequest.Abort();
return ms;
}
this.ManualResetMember();
if (null != this.OnGetResponseReadyHandler)
{
try
{
this.OnGetResponseReadyHandler(this.httpRequest);
}
catch (System.Exception ex)
{
this.LastAccessError = true;
BaseDebug.DebugPrint(ex.ToString());
}
}
this.DoBetIsGotoRecv = true;
Stream sm = httpResponse.GetResponseStream();
if (null != sm && sm.CanRead)
{
BinaryReader br = new BinaryReader(sm);
byte[] bytes = br.ReadBytes(DEFAULT_BUFFER_SIZE);
while (null != bytes && bytes.Length != 0)
{
ms.Write(bytes, 0, bytes.Length);
bytes = br.ReadBytes(DEFAULT_BUFFER_SIZE);
}
br.Close();
}
if (httpResponse.Headers["Set-Cookie"] != null)
this.CurSetCookie = httpResponse.Headers["Set-Cookie"].ToString();
httpResponse.Close();
if (null != sm) sm.Close();
// 非常重要,回到开头
ms.Seek(0, SeekOrigin.Begin);
}
catch (System.Exception ex)
{
this.LastAccessError = true;
BaseDebug.DebugPrint("異常網址:" + url);
BaseDebug.DebugPrint(ex.ToString());
if (null != httpRequest) httpRequest.Abort();
}
return ms;
}
public MemoryStream SimpleGetMemoryStream(string url, string method)
{
return this.GetMemoryStream(url, method, null, null, "text/html");
}
public MemoryStream SimpleGetMemoryStream(string url, string method, string httpAccept)
{
return this.GetMemoryStream(url, method, null, null, httpAccept);
}
/// <summary>
/// 仅仅发送请求,返回所有的输出文本
/// </summary>
/// <param name="url"></param>
/// <param name="method"></param>
/// <param name="coding"></param>
/// <param name="cc"></param>
/// <param name="referUrl"></param>
/// <returns></returns>
public string SimpleDoPostWrapper(string url, string method, Encoding coding, CookieCollection cc, string referUrl)
{
string str = string.Empty;
StreamReader sr = null;
MemoryStream sm = null;
if (null == coding)
{
sm = this.GetMemoryStream(url, method, cc, referUrl, "text/html");
sr = new StreamReader(sm);
}
else
{
sm = this.GetMemoryStream(url, method, cc, referUrl, "text/html");
sr = new StreamReader(sm, coding);
}
str = sr.ReadToEnd();
sr.Close();
sm.Close();
return str;
}
public string SimpleDoPostWrapper(string url, string method)
{
return this.SimpleDoPostWrapper(url, method, null, null, null);
}
public string SimpleDoPostWrapper(string url, string method, CookieCollection cc)
{
return this.SimpleDoPostWrapper(url, method, null, cc, null);
}
public string SimpleDoPostWrapper(string url, string method, string referUrl)
{
return this.SimpleDoPostWrapper(url, method, null, null, referUrl);
}
/// <summary>
/// 上送数据,返回输出流
/// </summary>
/// <param name="url"></param>
/// <param name="data"></param>
/// <param name="method"></param>
/// <param name="coding"></param>
/// <param name="cc"></param>
/// <param name="referUrl"></param>
/// <returns></returns>
public MemoryStream GetMemoryStream(string url, string data, string method, Encoding coding, CookieCollection cc, string referUrl)
{
MemoryStream ms = new MemoryStream();
try
{
this.SetHttpRequestOptions(url, method, cc, referUrl, "text/html");
byte[] bytesData = coding.GetBytes(data);
Stream requestStream = httpRequest.GetRequestStream();
requestStream.Write(bytesData, 0, bytesData.Length);
requestStream.Flush();
requestStream.Close();
this.httpResponse = (HttpWebResponse)httpRequest.GetResponse();
// 是否收到响应
if (!this.httpRequest.HaveResponse)
{
this.httpResponse.Close();
this.httpRequest.Abort();
return ms;
}
this.ManualResetMember();
if (null != this.OnGetResponseReadyHandler)
{
try
{
this.OnGetResponseReadyHandler(this.httpRequest);
}
catch (System.Exception ex)
{
this.LastAccessError = true;
BaseDebug.DebugPrint(ex.ToString());
}
}
this.DoBetIsGotoRecv = true;
Stream sm = httpResponse.GetResponseStream();
if (null != sm && sm.CanRead)
{
BinaryReader br = new BinaryReader(sm);
byte[] bytes = br.ReadBytes(DEFAULT_BUFFER_SIZE);
while (null != bytes && bytes.Length != 0)
{
ms.Write(bytes, 0, bytes.Length);
bytes = br.ReadBytes(DEFAULT_BUFFER_SIZE);
}
br.Close();
}
if (httpResponse.Headers["Set-Cookie"] != null)
this.CurSetCookie = httpResponse.Headers["Set-Cookie"].ToString();
httpResponse.Close();
if (null != sm) sm.Close();
// 非常重要,回到开头
ms.Seek(0, SeekOrigin.Begin);
}
catch (System.Exception ex)
{
this.LastAccessError = true;
BaseDebug.DebugPrint("異常網址:" + url);
BaseDebug.DebugPrint(ex.ToString());
if (null != httpRequest) httpRequest.Abort();
}
return ms;
}
public MemoryStream SimpleGetMemoryStream(string url, string data, string method, Encoding coding)
{
return this.GetMemoryStream(url, data, method, coding, null, null);
}
public MemoryStream SimpleGetMemoryStream(string url, string data, string method, Encoding coding, string referUrl)
{
return this.GetMemoryStream(url, data, method, coding, null, referUrl);
}
/// <summary>
/// 上送,返回所有的输出文本
/// </summary>
/// <param name="url"></param>
/// <param name="data"></param>
/// <param name="method"></param>
/// <param name="coding"></param>
/// <param name="referUrl"></param>
/// <returns></returns>
public string DoPostWrapper(string url, string data, string method, Encoding coding, CookieCollection cc, string referUrl)
{
string str = string.Empty;
MemoryStream sm = this.GetMemoryStream(url, data, method, coding, cc, referUrl);
StreamReader sr = new StreamReader(sm);
str = sr.ReadToEnd();
sr.Close();
sm.Close();
return str;
}
public string DoPostWrapper(string url, string data, string method, Encoding coding)
{
return this.DoPostWrapper(url, data, method, coding, null, null);
}
public string DoPostWrapper(string url, string data, string method, Encoding coding, CookieCollection cc)
{
return this.DoPostWrapper(url, data, method, coding, cc, null);
}
public string DoPostWrapper(string url, string data, string method, Encoding coding, string referUrl)
{
return this.DoPostWrapper(url, data, method, coding, null, referUrl);
}
/// <summary>
/// 上送,返回所有的输出文本,参数是字典
/// </summary>
/// <param name="url"></param>
/// <param name="dicArguments"></param>
/// <param name="method"></param>
/// <param name="coding"></param>
/// <param name="referUrl"></param>
/// <returns></returns>
public string DoPostWrapper(string url, Dictionary<string, string> dicArguments, string method, Encoding coding, CookieCollection cc, string referUrl)
{
string data = this.BuildRequestArguments(dicArguments);
return this.DoPostWrapper(url, data, method, coding, cc, referUrl);
}
public string DoPostWrapper(string url, Dictionary<string, string> dicArguments, string method, Encoding coding)
{
return this.DoPostWrapper(url, dicArguments, method, coding, null, null);
}
public string DoPostWrapper(string url, Dictionary<string, string> dicArguments, string method, Encoding coding, CookieCollection cc)
{
return this.DoPostWrapper(url, dicArguments, method, coding, cc, null);
}
public string DoPostWrapper(string url, Dictionary<string, string> dicArguments, string method, Encoding coding, string referUrl)
{
return this.DoPostWrapper(url, dicArguments, method, coding, null, referUrl);
}
/// <summary>
/// 下载验证码,只返回内存流,调用函数要负责关闭该Stream
/// </summary>
/// <param name="url"></param>
/// <param name="method"></param>
/// <returns></returns>
public MemoryStream DownloadStream(string url, string method)
{
return this.SimpleGetMemoryStream(url, method, "*/*");
}
/// <summary>
/// 从字典中生成上传参数.提供编码定制支持
/// </summary>
/// <param name="dicArguments"></param>
/// <param name="coding"></param>
/// <returns></returns>
public string BuildRequestArguments(Dictionary<string, string> dicArguments, Encoding coding)
{
StringBuilder sb = new StringBuilder();
string str = string.Empty;
if (0 == dicArguments.Count) return str;
foreach (KeyValuePair<string, string> kvp in dicArguments)
{
if(null != coding)
sb.Append(HttpUtility.UrlEncode(kvp.Key, coding) + "=" + HttpUtility.UrlEncode(kvp.Value, coding));
else
sb.Append(HttpUtility.UrlEncode(kvp.Key) + "=" + HttpUtility.UrlEncode(kvp.Value));
// a&b
sb.Append("&");
}
str = sb.ToString();
return str.Substring(0, str.Length - 1);
}
/// <summary>
/// 从字典中生成上传的默认参数,不提供编码定制支持
/// </summary>
/// <param name="dicArguments"></param>
/// <returns></returns>
public string BuildRequestArguments(Dictionary<string, string> dicArguments)
{
return this.BuildRequestArguments(dicArguments, null);
}
/// <summary>
/// 查询cookie中的某个项的值
/// </summary>
/// <param name="key"></param>
/// <param name="domain"></param>
/// <returns></returns>
public string GetCookieValue(string key, string domain)
{
if (0 == this.cookieContainer.Count)
{
return string.Empty;
}
CookieCollection cc = this.cookieContainer.GetCookies(new Uri(domain));
return cc[key].Value;
}
/// <summary>
/// 设置cookies容器
/// </summary>
/// <param name="cc"></param>
public void SetCookieContainer(CookieContainer cc)
{
this.cookieContainer = cc;
}
/// <summary>
/// 放棄請求
/// </summary>
public bool AbortHttpRequest()
{
if(null != this.httpRequest)
{
this.httpRequest.Abort();
}
return this.CheckGotoRecv && this.DoBetIsGotoRecv;
}
}
}