【C#、csharp】HTTPGET，POST请求

HTTP定义了与服务器交互的不同方法，基本方法有GET，POST，PUT，DELETE，分别对于查，该，增，删。一般情况下我们只用到GET和POST，其他两种都也可以用GET和POST来实现，很多浏览器也只实现了GET和POST两种方法

　　GET：用户获取信息

　　　　安全的：不会对服务器上的数据进行修改，和破坏

　　　　幂等的：相同的请求所返回的结果相同

　　　　参数是通过Url来传输，接在Url后面中间用?分开，不同参数之间用&分开，下面表示传递两个参数param1和param2，值为value1和value2

　　　　　　http://songurl/index.htm?param1=value1&param2=value2

　　　　通过上面可以看到，GET请求数据在隐私方面又是不安全的，因为Url上的信息可以直接让用户看到，这样不利于隐私保护

　　POST：用于更新数据

　　　　传递的数据对用户隐藏，封装在包里，具体看演示

　　　　有时候请求会重定向，但我们就需要从重定向url获取东西，这时可以设置重定向禁用，你就可以从headers的Location属性中获取重定向地址

　　　　　　request.AllowAutoRedirect = false;

　　　　　　string[] values = request.Headers.GetValues("Location");

下面是辅助类的定义

        public class HttpHelper

        {

            /// <summary>  

            /// 创建GET方式的HTTP请求  

            /// </summary>  

            public static HttpWebResponse CreateGetHttpResponse(string url, int timeout, string userAgent, CookieCollection cookies)

            {

                HttpWebRequest request = null;

                if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))

                {

                    //对服务端证书进行有效性校验（非第三方权威机构颁发的证书，如自己生成的，不进行验证，这里返回true）

                    ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);

                    request = WebRequest.Create(url) as HttpWebRequest;

                    request.ProtocolVersion = HttpVersion.Version10;    //http版本，默认是1.1,这里设置为1.0

                }

                else

                {

                    request = WebRequest.Create(url) as HttpWebRequest;

                }

                request.Method = "GET";

                

                //设置代理UserAgent和超时

                //request.UserAgent = userAgent;

                //request.Timeout = timeout;

                if (cookies != null)

                {

                    request.CookieContainer = new CookieContainer();

                    request.CookieContainer.Add(cookies);

                }

                return request.GetResponse() as HttpWebResponse;

            }

            

            /// <summary>  

            /// 创建POST方式的HTTP请求  

            /// </summary>  

            public static HttpWebResponse CreatePostHttpResponse(string url, IDictionary<string, string> parameters, int timeout, string userAgent, CookieCollection cookies)

            {

                HttpWebRequest request = null;

                //如果是发送HTTPS请求  

                if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))

                {

                    //ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);

                    request = WebRequest.Create(url) as HttpWebRequest;

                    //request.ProtocolVersion = HttpVersion.Version10;

                }

                else

                {

                    request = WebRequest.Create(url) as HttpWebRequest;

                }

                request.Method = "POST";

                request.ContentType = "application/x-www-form-urlencoded";



                //设置代理UserAgent和超时

                //request.UserAgent = userAgent;

                //request.Timeout = timeout; 



                if (cookies != null)

                {

                    request.CookieContainer = new CookieContainer();

                    request.CookieContainer.Add(cookies);

                }

                //发送POST数据  

                if (!(parameters == null || parameters.Count == 0))

                {

                    StringBuilder buffer = new StringBuilder();

                    int i = 0;

                    foreach (string key in parameters.Keys)

                    {

                        if (i > 0)

                        {

                            buffer.AppendFormat("&{0}={1}", key, parameters[key]);

                        }

                        else

                        {

                            buffer.AppendFormat("{0}={1}", key, parameters[key]);

                            i++;

                        }

                    }

                    byte[] data = Encoding.ASCII.GetBytes(buffer.ToString());

                    using (Stream stream = request.GetRequestStream())

                    {

                        stream.Write(data, 0, data.Length);

                    }

                }

                string[] values = request.Headers.GetValues("Content-Type");

                return request.GetResponse() as HttpWebResponse;

            }



            /// <summary>

            /// 获取请求的数据

            /// </summary>

            public static string GetResponseString(HttpWebResponse webresponse)

            {

                using (Stream s = webresponse.GetResponseStream())

                {

                    StreamReader reader = new StreamReader(s, Encoding.UTF8);

                    return reader.ReadToEnd();



                }

            }

            

            /// <summary>

            /// 验证证书

            /// </summary>

            private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)

            {

                if (errors == SslPolicyErrors.None)

                    return true;

                return false;

            }  

        }