轉自原文 【C#】HTTP請求GET，POST

HTTP定義了與服務器交互的不同方法，基本方法有GET，POST，PUT，DELETE，分別對於查，該，增，刪。一般情況下我們只用到GET和POST，其他兩種都也可以用GET和POST來實現，很多瀏覽器也只實現了GET和POST兩種方法

　　GET：用戶獲取信息

　　　　安全的：不會對服務器上的數據進行修改，和破壞

　　　　冪等的：相同的請求所返回的結果相同

　　　　參數是通過Url來傳輸，接在Url後面中間用?分開，不同參數之間用&分開，下面表示傳遞兩個參數param1和param2，值為value1和value2

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

　　　　通過上面可以看到，GET請求數據在隱私方面又是不安全的，因為Url上的信息可以直接讓用戶看到，這樣不利於隱私保護

　　POST：用於更新數據

　　　　傳遞的數據對用戶隱藏，封裝在包裏，具體看演示

　　　　有時候請求會重定向，但我們就需要從重定向url獲取東西，這時可以設置重定向禁用，你就可以從headers的Location屬性中獲取重定向地址

　　　　　　request.AllowAutoRedirect = false;

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

下面是輔助類的定義

public class HttpHelper
        {
            /// <summary>  
            /// 創建GET方式的HTTP請求  
            /// </summary>  
            public static HttpWebResponse CreateGetHttpResponse(string url, int timeout, string userAgent, CookieCollection cookies)
            {
                HttpWebRequest request 
 
= null;
                if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
                {
                    //對服務端證書進行有效性校驗（非第三方權威機構頒發的證書，如自己生成的，不進行驗證，這裏返回true）
                    ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                    request = WebRequest.Create(url) as HttpWebRequest;
                    request.ProtocolVersion = HttpVersion.Version10;    //http版本，默認是1.1,這裏設置為1.0
                }
                else
                {
                    request = WebRequest.Create(url) as HttpWebRequest;
                }
                request.Method = "GET";
                
                //設置代理UserAgent和超時
                //request.UserAgent = userAgent;
                //request.Timeout = timeout;
                if (cookies != null)
                {
                    request.CookieContainer = new CookieContainer();
                    request.CookieContainer.Add(cookies);
                }
                return request.GetResponse() as HttpWebResponse;
            }
            
            /// <summary>  
            /// 創建POST方式的HTTP請求  
            /// </summary>  
            public static HttpWebResponse CreatePostHttpResponse(string url, IDictionary<string, string> parameters, int timeout, string userAgent, CookieCollection cookies)
            {
                HttpWebRequest request = null;
                //如果是發送HTTPS請求  
                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";

                //設置代理UserAgent和超時
                //request.UserAgent = userAgent;
                //request.Timeout = timeout; 

                if (cookies != null)
                {
                    request.CookieContainer = new CookieContainer();
                    request.CookieContainer.Add(cookies);
                }
                //發送POST數據  
                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>
            /// 獲取請求的數據
            /// </summary>
            public static string GetResponseString(HttpWebResponse webresponse)
            {
                using (Stream s = webresponse.GetResponseStream())
                {
                    StreamReader reader = new StreamReader(s, Encoding.UTF8);
                    return reader.ReadToEnd();

                }
            }
            
            /// <summary>
            /// 驗證證書
            /// </summary>
            private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
            {
                if (errors == SslPolicyErrors.None)
                    return true;
                return false;
            }  
        }

C# HTTP請求GET，POST