HTTP基本认证原理

在HTTP协议进行通信的过程中，HTTP协议定义了基本认证过程以允许HTTP服务器对WEB浏览器进行用户身份认证的方法，当一个客户端向HTTP服务器进行数据请求时，如果客户端未被认证，则HTTP服务器将通过基本认证过程对客户端的用户名及密码进行验证，以决定用户是否合法。

其基本的实现方式是：

客户端在用户输入用户名及密码后，将用户名及密码以BASE64加密，加密后的密文将附加于请求信息中，如当用户名为Parry，密码为123456时，客户端将用户名和密码用":"合并，并将合并后的字符串用BASE64加密，并于每次请求数据时，将密文附加于请求头（Request Header）中。

HTTP服务器在每次收到请求包后，根据协议取得客户端附加的用户信息（BASE64加密的用户名和密码），解开请求包，对用户名及密码进行验证，如果用户名及密码正确，则根据客户端请求，返回客户端所需要的数据；否则，返回错误代码或重新要求客户端提供用户名及密码。

摘自：http://www.cnblogs.com/parry/archive/2012/11/09/ASPNET_MVC_Web_API_HTTP_Basic_Authorize.html

继承System.Web.Http.AuthorizeAttribute

 public class HTTPBasicAuthorizeAttribute : System.Web.Http.AuthorizeAttribute
    {
        public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)
        {
            if (actionContext.Request.Headers.Authorization != null)
            {
                string userInfo = Encoding.Default.GetString(Convert.FromBase64String(actionContext.Request.Headers.Authorization.Parameter));

                if (string.Equals(userInfo, string.Format("{0}:{1}", "admin", "aadmin")))
                {
                    IsAuthorized(actionContext);
                }
                else
                {
                    HandleUnauthorizedRequest(actionContext);
                }
            }
            else
            {
                HandleUnauthorizedRequest(actionContext);
            }
        }
        protected override void HandleUnauthorizedRequest(System.Web.Http.Controllers.HttpActionContext actionContext)
        {
            var challengeMessage = new System.Net.Http.HttpResponseMessage(System.Net.HttpStatusCode.Unauthorized);
            challengeMessage.Headers.Add("WWW-Authenticate", "Basic");
            throw new System.Web.Http.HttpResponseException(challengeMessage);
        }
    }

客户端2种不同方式调用：

  public static string GetPersonsByRequest()
        {
            try
            {
                var userName = "admin";
                var passWord = "aadmin";
                string url = "http://localhost:4067/api/persons";
                string ResultJson = "";
                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
                request.Method = "GET";//设置请求方式
                request.ContentType = "application/x-www-form-urlencoded";
                //request.ContentType = "text/xml; charset=utf-8";//设置返回xml
                request.Credentials = CredentialCache.DefaultCredentials;
                request.Timeout = 1000 * 1000;//设置超时时间
                //设置户名密码的Base64编码，添加Authorization到HTTP头
                request.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(Encoding.ASCII.GetBytes(string.Format("{0}:{1}", userName, passWord))));
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();

                if (response.StatusCode == HttpStatusCode.OK)
                {
                    Stream responseStream = response.GetResponseStream();
                    System.IO.StreamReader str = new System.IO.StreamReader(responseStream, System.Text.Encoding.GetEncoding("UTF-8"));//设置编码
                    ResultJson = str.ReadToEnd();
                    response.Close();
                    str.Close();
                }
                return ResultJson;
            }
            catch (Exception ex)
            {
                return ex.ToString();
            }
        }
        //推荐使用，需要net4.0以上版本支持
        public static async Task<string> GetPersonsByClient()
        {
            try
            {
                string responseBody = "";
                var userName = "admin";
                var passWord = "aadmin";
                using (HttpClient client = new HttpClient())
                {
                    //绑定请求地址
                    client.BaseAddress = new Uri("http://localhost:4067/");
                    client.DefaultRequestHeaders.Accept.Add(
                        new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
                    //设置Http请求验证信息
                    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic",
                        Convert.ToBase64String(System.Text.ASCIIEncoding.ASCII.GetBytes(string.Format("{0}:{1}", userName, passWord))));
                    using (HttpResponseMessage response = client.GetAsync("api/persons").Result)
                    {
                        if (response.IsSuccessStatusCode)//判断响应是否成功！
                        {
                            responseBody = await response.Content.ReadAsStringAsync();
                        }
                    }
                }
                return responseBody;
            }
            catch (Exception ex)
            {
                return ex.ToString();
            }
        }
        private static string RequestResult(TypeMethods tppe)
        {
            string Result = "";
            switch (tppe)
            {
                case TypeMethods.HttpClient:
                    Result = GetPersonsByClient().Result;
                    break;
                case TypeMethods.HttpWebRequest:
                    Result = GetPersonsByRequest();
                    break;
                default:
                    break;
            }
            return Result;

        }
        [Flags]
        public enum TypeMethods
        {
            HttpClient = 1,
            HttpWebRequest = 2,
        }
        static void Main(string[] args)
        {
            string json1 = RequestResult(TypeMethods.HttpClient);
            string json2 = RequestResult(TypeMethods.HttpWebRequest);

        }
    }