c#如何通过Socket访问网站资源-创新互联
引言
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在C#中,我们通常会使用HttpWebRequest来访问url资源,例子如下:
public static string GetContentFromUrl(string url) { HttpWebResponse response = null; WebRequest request; try { request = WebRequest.Create(url); // make sure it accept gzip request.Headers.Set("Accept-Encoding", "gzip, deflate"); request.Timeout = 100000; response = (HttpWebResponse)request.GetResponse(); Stream responseStream = response.GetResponseStream(); string sXML = null; Stream unzipStream = null; StreamReader outSr = null; switch(response.ContentEncoding) { case "gzip": // get the gzip stream and unzipped unzipStream = new GZipStream(responseStream, CompressionMode.Decompress); outSr = new StreamReader(unzipStream); break; case "deflate": unzipStream = new DeflateStream(responseStream, CompressionMode.Decompress); outSr = new StreamReader(unzipStream); break; default: outSr = new StreamReader(responseStream); break; } sXML = outSr.ReadToEnd(); response.Close(); } catch (WebException ex) { Console.WriteLine(ex.Message); } return null; }
当遇到HttpStatusCode>400时,通常会被认为是WebException,错误消息会带上StatusCode如
The remote server returned an error: (401) Unauthorized.
有时候,当401发生时,服务器会在Response里告诉你具体的错误信息,如
因为HttpWebRequest类会把HttpStatusCode>=400当做WebException,这样的话我们就无法获取到Response Stream中的内容啦。
怎样才能获取具体的错误信息,然后根据错误信息做具体的处理呢?
我们可以通过Socket来访问url资源,下面是具体实现的类
RequestHeader
namespace Com.Morningstar.EquityData.XOIAccessor.Http { public static class RequestHeader { public const string Host = "Host"; public const string AcceptEncoding = "Accept-Encoding"; public const string AcceptLanguage = "Accept-Language"; public const string Accept = "Accept"; public const string Connection = "Connection"; public const string Cookie = "Cookie"; public const string UserAgent = "User-Agent"; public const string ContentType = "Content-Type"; public const string ContentLength = "Content-Length"; } public static class ResponseHeader { public static string ContentLength = "Content-Length"; public static string ContentType = "Content-Type"; public static string ContentEncoding = "Content-Encoding"; public static string SetCookie = "Set-Cookie"; } public static class Connection { public static string KeepAlive = "Keep-Alive"; public static string Close = "Close"; } }
HttpMethod
namespace Com.Morningstar.EquityData.XOIAccessor.Http { public enum HttpMethod { GET,POST } }
HttpException
namespace Com.Morningstar.EquityData.XOIAccessor.Http { public class HttpException:Exception { public HttpException(string message) : base(message) { } public HttpException(string message, Exception innerException) : base(message, innerException) { } } }
HttpRequest:建立Http请求,并且返回HttpResponse
namespace Com.Morningstar.EquityData.XOIAccessor.Http { public class HttpRequest { internal HttpRequest() { } public string Host { set; get; } private int port = 80; public int Port { set { if (port > 0) { port = value; } } get { return port; } } private HttpMethod method = HttpMethod.GET; public HttpMethod Method { set { method = value; } get { return method; } } private string path = "/"; public string Path { set { path = value; } get { return path; } } private NameValueCollection headers = new NameValueCollection(); public NameValueCollection Headers { set { headers = value; } get { return headers; } } public void AddHeader(string name, string value) { headers[name] = value; } public string Body { set; get; } ////// Millseconds to wait response /// private int timeout = -1;//Never time out public int Timeout { set { if (timeout < -1) { throw new ArgumentOutOfRangeException("Timeout is less than -1"); } timeout = value; } get { return timeout; } } private void CheckReqiredParameters() { if (string.IsNullOrEmpty(Host)) { throw new ArgumentException("Host is blank"); } } public string BuilSocketRequest() { StringBuilder requestBuilder = new StringBuilder(); FillHeader(); BuildRequestLine(requestBuilder); BuildRequestHeader(requestBuilder); BuildRequestBody(requestBuilder); return requestBuilder.ToString(); } private void FillHeader() { if (Method.Equals(HttpMethod.POST)) { if (string.IsNullOrEmpty(Headers[RequestHeader.ContentType])) { Headers[RequestHeader.ContentType] = "application/x-www-form-urlencoded"; } if (!string.IsNullOrEmpty(Body) && string.IsNullOrEmpty(Headers[RequestHeader.ContentLength])) { Headers[RequestHeader.ContentLength] = Encoding.Default.GetBytes(Body).Length.ToString(); } } if (!string.IsNullOrEmpty(Headers[RequestHeader.Connection])) { Headers[RequestHeader.Connection] = Connection.Close; } if (string.IsNullOrEmpty(Headers[RequestHeader.Accept])) { Headers[RequestHeader.Accept] = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"; } if (string.IsNullOrEmpty(Headers[RequestHeader.UserAgent])) { Headers[RequestHeader.UserAgent] = "Mozilla/5.0 (Windows NT 6.1; IE 9.0)"; } if (string.IsNullOrEmpty(Headers[RequestHeader.AcceptEncoding])) { Headers[RequestHeader.AcceptEncoding] = "gzip, deflate"; } if (string.IsNullOrEmpty(Headers[RequestHeader.Host])) { Headers[RequestHeader.Host] = Host; } } private void BuildRequestLine(StringBuilder requestBuilder) { if (Method.Equals(HttpMethod.POST)) { requestBuilder.AppendLine(string.Format("POST {0} HTTP/1.1", Path)); } else { requestBuilder.AppendLine(string.Format("GET {0} HTTP/1.1", Path)); } } private void BuildRequestHeader(StringBuilder requestBuilder) { foreach (string name in Headers) { requestBuilder.AppendLine(string.Format("{0}: {1}", name, Headers[name])); } } private void BuildRequestBody(StringBuilder requestBuilder) { requestBuilder.AppendLine(); if (!string.IsNullOrEmpty(Body)) { requestBuilder.Append(Body); } } public HttpResponse GetResponse() { CheckReqiredParameters(); HttpResponse httpResponse = new HttpResponse(); string socketRequest = BuilSocketRequest(); byte[] requestBytes = Encoding.ASCII.GetBytes(socketRequest); try { using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)) { socket.ReceiveTimeout = Timeout; socket.Connect(Host, Port); if (socket.Connected) { socket.Send(requestBytes); ParseResponseLine(socket, httpResponse); ParseResponseHeader(socket, httpResponse); ParseResponseBody(socket, httpResponse); socket.Close(); } } } catch (Exception e) { throw new HttpException("Get response failure. Host:" + Host + ", Port:" + Port + ",RequestString:" + socketRequest, e); } return httpResponse; } private void ParseResponseLine(Socket socket, HttpResponse response) { string responseLine = ReceiveCharBytes(socket, "\r\n"); responseLine = responseLine.Replace("\r\n", ""); string[] fields = responseLine.Split(' '); if (fields.Length >= 3) { response.StatusCode = fields[1]; response.StatusDescription = responseLine.Substring(responseLine.IndexOf(fields[1]) + fields[1].Length + 1); } else { throw new HttpException("The response line:'" + responseLine + "' has the wrong format."); } } private void ParseResponseHeader(Socket socket, HttpResponse response) { string responseHeader = ReceiveCharBytes(socket, "\r\n\r\n"); string[] headerArry = Regex.Split(responseHeader, "\r\n"); if (headerArry != null) { foreach (string header in headerArry) { if (!string.IsNullOrEmpty(header)) { int start = header.IndexOf(":"); if (start > 0) { string name = header.Substring(0, start); string value = ""; if(header.Length>start+2){ value = header.Substring(start + 2); } response.AddHeader(name, value); } } } } } private string ReceiveCharBytes(Socket socket, string breakFlag) { StringBuilder builder = new StringBuilder(); while (true) { byte[] buff = new byte[1]; int read = socket.Receive(buff, SocketFlags.None); if (read > 0) { builder.Append((char)buff[0]); } if (builder.ToString().EndsWith(breakFlag)) { break; } } return builder.ToString(); } private void ParseResponseBody(Socket socket, HttpResponse response) { string contentLen = response.GetHeader(ResponseHeader.ContentLength); bool bodyDone = false; if (!string.IsNullOrEmpty(contentLen)) { int len = Convert.ToInt32(contentLen); if (len > 0) { byte[] contentBytes = new byte[len]; if (socket.Receive(contentBytes) > 0) { response.Body = contentBytes; } bodyDone = true; } } if (!bodyDone) { ListreadsList = new List (); int totalLength = 0; while (true) { byte[] buff = new byte[1024]; int readLen = socket.Receive(buff); if (readLen > 0) { totalLength += readLen; byte[] reads = new byte[readLen]; Array.Copy(buff, 0, reads, 0, readLen); readsList.Add(reads); } else { break; } } byte[] fullBytes = new byte[totalLength]; int index = 0; foreach (byte[] reads in readsList) { Array.Copy(reads, 0, fullBytes, index, reads.Length); index += reads.Length; } response.Body = fullBytes; } } private string GetResponseHeader(Socket socket) { StringBuilder builder = new StringBuilder(); while (true) { byte[] buff = new byte[1]; int read = socket.Receive(buff, SocketFlags.None); if (read > 0) { builder.Append((char)buff[0]); } if (builder.ToString().Contains("\r\n\r\n")) { break; } } return builder.ToString(); } public static HttpRequest Create(string url) { Uri uri = new Uri(url); HttpRequest request = new HttpRequest(); request.Host = uri.Host; request.Port = uri.Port; request.Path = uri.PathAndQuery; return request; } } }
HttpResponse:对Http的响应流进行封装
namespace Com.Morningstar.EquityData.XOIAccessor.Http { public class HttpResponse { internal HttpResponse() { } #region Response Line public string StatusCode { internal set; get; } public string StatusDescription{ internal set;get; } #endregion #region Response Headers private NameValueCollection headers = new NameValueCollection(); public NameValueCollection Headers { get { return headers; } } internal void AddHeader(string name, string value) { headers[name] = value; } public string GetHeader(string name) { return headers[name]; } public long? ContentLength { get { if(!string.IsNullOrEmpty(GetHeader(ResponseHeader.ContentLength))) { return Convert.ToInt64(GetHeader(ResponseHeader.ContentLength)); } return null; } } public string ContentEncoding { get { return GetHeader(ResponseHeader.ContentEncoding); } } #endregion public byte[] Body { internal set; get; } public Stream GetBodyStream() { if (Body != null) { return new MemoryStream(Body); } return null; } } }
如何使用HttpRequest类
public string GetContent(string url) { Login(); HttpRequest request = HttpRequest.Create(url); request.Method = HttpMethod.GET; request.AddHeader(RequestHeader.AcceptEncoding, "gzip, deflate"); request.AddHeader(RequestHeader.Cookie, AuthCookie); request.Timeout = Timeout; HttpResponse resp = request.GetResponse(); string xoiErrorCode = resp.GetHeader("X-XOI-ErrorCode"); if (!string.IsNullOrEmpty(xoiErrorCode)) { if (!xoiErrorCode.Equals(XOIErrorCode.XOI_EC_40401)) { XOIException xoiException = new XOIException("Get content fail. Url:" + url); string errorContent = ReadContent(resp); XmlDocument doc = new XmlDocument(); doc.LoadXml(errorContent); XmlNode statusCodeNode = doc.SelectSingleNode(@"/XOIException/StatusCode"); XmlNode statusMessageNode = doc.SelectSingleNode(@"/XOIException/StatusMessage"); if (statusCodeNode != null) { xoiException.XOIErrorCode = statusCodeNode.Value; } if (statusMessageNode != null) { xoiException.XOIErrorInfo = statusMessageNode.Value; } throw xoiException; } else { return string.Empty; } } return ReadContent(resp); } protected string ReadContent(HttpResponse resp) { StreamReader reader = null; try { switch (resp.ContentEncoding) { case "gzip": reader = new StreamReader(new GZipStream(resp.GetBodyStream(), CompressionMode.Decompress)); break; case "deflate": reader = new StreamReader(new DeflateStream(resp.GetBodyStream(), CompressionMode.Decompress)); break; default: reader = new StreamReader(resp.GetBodyStream()); break; } return reader.ReadToEnd(); } finally { if (reader != null) { reader.Close(); } } }
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