微信公众平台开发：OAuth2.0说明

namespace Senparc.Weixin.MP.AdvancedAPIs
{
    //官方文档：http://mp.weixin.qq.com/wiki/index.php?title=%E7%BD%91%E9%A1%B5%E6%8E%88%E6%9D%83%E8%8E%B7%E5%8F%96%E7%94%A8%E6%88%B7%E5%9F%BA%E6%9C%AC%E4%BF%A1%E6%81%AF#.E7.AC.AC.E4.B8.80.E6.AD.A5.EF.BC.9A.E7.94.A8.E6.88.B7.E5.90.8C.E6.84.8F.E6.8E.88.E6.9D.83.EF.BC.8C.E8.8E.B7.E5.8F.96code

    /// <summary>
    /// 应用授权作用域
    /// </summary>
    public enum OAuthScope
    {
        /// <summary>
        /// 不弹出授权页面，直接跳转，只能获取用户openid
        /// </summary>
        snsapi_base,
        /// <summary>
        /// 弹出授权页面，可通过openid拿到昵称、性别、所在地。并且，即使在未关注的情况下，只要用户授权，也能获取其信息
        /// </summary>
        snsapi_userinfo
    }

    public static class OAuth
    {
        /// <summary>
        /// 获取验证地址
        /// </summary>
        /// <param name="appId"></param>
        /// <param name="redirectUrl"></param>
        /// <param name="state"></param>
        /// <param name="scope"></param>
        /// <param name="responseType"></param>
        /// <returns></returns>
        public static string GetAuthorizeUrl(string appId, string redirectUrl, string state, OAuthScope scope, string responseType = "code")
        {
            var url =
                string.Format("https://open.weixin.qq.com/connect/oauth2/authorize?appid={0}&redirect_uri={1}&response_type={2}&scope={3}&state={4}#wechat_redirect",
                                appId, redirectUrl.UrlEncode(), responseType, scope, state);

            /* 这一步发送之后，客户会得到授权页面，无论同意或拒绝，都会返回redirectUrl页面。
             * 如果用户同意授权，页面将跳转至 redirect_uri/?code=CODE&state=STATE。这里的code用于换取access_token（和通用接口的access_token不通用）
             * 若用户禁止授权，则重定向后不会带上code参数，仅会带上state参数redirect_uri?state=STATE
             */
            return url;
        }

        /// <summary>
        /// 获取AccessToken
        /// </summary>
        /// <param name="appId"></param>
        /// <param name="secret"></param>
        /// <param name="code">code作为换取access_token的票据，每次用户授权带上的code将不一样，code只能使用一次，5分钟未被使用自动过期。</param>
        /// <param name="grantType"></param>
        /// <returns></returns>
        public static OAuthAccessTokenResult GetAccessToken(string appId, string secret, string code, string grantType = "authorization_code")
        {
            var url =
                string.Format("https://api.weixin.qq.com/sns/oauth2/access_token?appid={0}&secret={1}&code={2}&grant_type={3}",
                                appId, secret, code, grantType);

            return CommonJsonSend.Send<OAuthAccessTokenResult>(null, url, null, CommonJsonSendType.GET);
        }

        /// <summary>
        /// 刷新access_token（如果需要）
        /// </summary>
        /// <param name="appId"></param>
        /// <param name="refreshToken">填写通过access_token获取到的refresh_token参数</param>
        /// <param name="grantType"></param>
        /// <returns></returns>
        public static OAuthAccessTokenResult RefreshToken(string appId, string refreshToken, string grantType = "refresh_token")
        {
            var url =
                string.Format("https://api.weixin.qq.com/sns/oauth2/refresh_token?appid={0}&grant_type={1}&refresh_token={2}",
                                appId, grantType, refreshToken);

            return CommonJsonSend.Send<OAuthAccessTokenResult>(null, url, null, CommonJsonSendType.GET);
        }

        public static OAuthUserInfo GetUserInfo(string accessToken,string openId)
        {
            var url = string.Format("https://api.weixin.qq.com/sns/userinfo?access_token={0}&openid={1}",accessToken,openId);
            return CommonJsonSend.Send<OAuthUserInfo>(null, url, null, CommonJsonSendType.GET);
        }
    }
}