public class OAuthServerProvider : OAuthAuthorizationServerProvider

     {

         /// <summary>

         /// 验证OAuth请求

         /// </summary>

         /// <param name="context"></param>

         /// <returns></returns>

         public override Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)

         {

             string clientId;

             string clientSecret;

             //获取客户端凭证

             if (!context.TryGetBasicCredentials(out clientId, out clientSecret))

                 context.TryGetFormCredentials(out clientId, out clientSecret);

             //保存客户端凭证

             context.OwinContext.Set<string>("clientId", clientId);

             context.OwinContext.Set<string>("clientSecret", clientSecret);

             //验证通过

             context.Validated(clientId);

             return base.ValidateClientAuthentication(context);

         }

         /// <summary>

         /// 客户端模式 验证

         /// </summary>

         /// <param name="context"></param>

         /// <returns></returns>

         public override Task GrantClientCredentials(OAuthGrantClientCredentialsContext context)

         {

             var clientSecret = context.OwinContext.Get<string>("clientSecret");

             if (context.ClientId == "admin" && clientSecret == "")

             {

                 var oAuthIdentity = new ClaimsIdentity(context.Options.AuthenticationType);

                 oAuthIdentity.AddClaim(new Claim(ClaimTypes.Name, "Clear App"));

                 var ticket = new AuthenticationTicket(oAuthIdentity, new AuthenticationProperties());

                 context.Validated(ticket);

             }

             else

             {

                 context.SetError("invalid_grant", "The username or password is incorrect.");

             }

             return base.GrantClientCredentials(context);

         }

         /// <summary>

         /// 密码模式验证

         /// </summary>

         /// <param name="context"></param>

         /// <returns></returns>

         public override Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)

         {

             if (context.UserName == "admin" && context.Password == "")

             {

                 var oAuthIdentity = new ClaimsIdentity(context.Options.AuthenticationType);

                 oAuthIdentity.AddClaim(new Claim(ClaimTypes.Name, context.UserName));

                 var ticket = new AuthenticationTicket(oAuthIdentity, new AuthenticationProperties());

                 //替换上下文中票证信息，并将其标记为已验证

                 context.Validated(ticket);

             }

             else

             {

                 context.SetError("invalid_grant", "The username or password is incorrect.");

             }

             return base.GrantResourceOwnerCredentials(context);

         }

     }

  public class Startup

     {

         public void Configuration(IAppBuilder app)

         {

             var options = new OAuthAuthorizationServerOptions()

             {

                 TokenEndpointPath = new PathString("/oauth2/token"),//获取token访问路径

                 Provider = new OAuthServerProvider(),//oauth2服务配置

                 AccessTokenExpireTimeSpan = TimeSpan.FromDays(),//token有效期

                 AllowInsecureHttp = true

             };

             app.UseOAuthBearerTokens(options);

         }

     }