创建一个webapi项目，不进行身份认证

创建webapi

通过Nuget引入下面的组件

Microsoft.AspNet.WebApi.Owin
Microsoft.Owin.Host.SystemWeb
Microsoft.Owin.Security.OAuth
Microsoft.Owin.Security.Cookies
Microsoft.AspNet.Identity.Owin
Microsoft.Owin.Cors

在项目下新建Startup类，这个类将作为owin的启动入口

修改startup的内容

[assembly: OwinStartup(typeof(OAuth.Startup))]
namespace OAuth
{
    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            //ConfigureAuth(app);
            MyConfigAuth(app);
            HttpConfiguration config = new HttpConfiguration();
            WebApiConfig.Register(config);
            app.UseCors(CorsOptions.AllowAll);
            app.UseWebApi(config);
        }
        public void MyConfigAuth(IAppBuilder app)
        {
            OAuthAuthorizationServerOptions option = new OAuthAuthorizationServerOptions()
            {
                AllowInsecureHttp = true,
                TokenEndpointPath = new PathString("/token"), //获取 access_token 授权服务请求地址
                AccessTokenExpireTimeSpan = TimeSpan.FromDays(1), //access_token 过期时间
                Provider = new SimpleAuthorizationServerProvider(), //access_token 相关授权服务
                RefreshTokenProvider = new SimpleRefreshTokenProvider() //refresh_token 授权服务
            };
            app.UseOAuthAuthorizationServer(option);
            app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
        }
    }
}

OAuth身份认证，新建SimpleAuthorizationServerProvider类

namespace OAuth.OAuth
{
    public class SimpleAuthorizationServerProvider : OAuthAuthorizationServerProvider
    {
        public override Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
        {
            context.Validated();
            return Task.FromResult<object>(null);
        }
        public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
        {
            context.OwinContext.Response.Headers.Add("Access-Control-Allow-Origin", new[] { "*" });

            /*
             * 对用户名、密码进行数据校验，这里我们省略
            using (AuthRepository _repo = new AuthRepository())
            {
                IdentityUser user = await _repo.FindUser(context.UserName, context.Password);

                if (user == null)
                {
                    context.SetError("invalid_grant", "The user name or password is incorrect.");
                    return;
                }
            }*/

            var identity = new ClaimsIdentity(context.Options.AuthenticationType);
            identity.AddClaim(new Claim("sub", context.UserName));
            identity.AddClaim(new Claim("role", "user"));

            context.Validated(identity);
        }
    }
}

新建SimpleRefreshTokenProvider类

namespace OAuth.OAuth
{
    public class SimpleRefreshTokenProvider : AuthenticationTokenProvider
    {
        private static ConcurrentDictionary<string, string> _refreshTokens = new ConcurrentDictionary<string, string>();

        /// <summary>
        /// 生成 refresh_token
        /// </summary>
        public override void Create(AuthenticationTokenCreateContext context)
        {
            context.Ticket.Properties.IssuedUtc = DateTime.UtcNow;
            context.Ticket.Properties.ExpiresUtc = DateTime.UtcNow.AddDays(60);

            context.SetToken(Guid.NewGuid().ToString("n"));
            _refreshTokens[context.Token] = context.SerializeTicket();
        }

        /// <summary>
        /// 由 refresh_token 解析成 access_token
        /// </summary>
        public override void Receive(AuthenticationTokenReceiveContext context)
        {
            string value;
            if (_refreshTokens.TryRemove(context.Token, out value))
            {
                context.DeserializeTicket(value);
            }
        }
    }
}

js调用

 <script>
        function getToken() {
            var data = {
                'password': '1',
                'username': '1',
                'grant_type': 'password'
            };

        $.ajax({
            url: "http://localhost:52386/token",
            type: "post",
            data: data,
            async: false,
            contentType: 'application/x-www-form-urlencoded',
            success: function (sResponse) {
                console.log('refresh_token ok: ' + sResponse.access_token + '  expires_in:' + sResponse.expires_in);
            },
            error: function (a, b, c) {
                if (a.status == 400 && a.responseJSON.error == 'invalid_grant') {
                    console.log('refresh token invalid');
                }
            }
            });
        }
    </script>