ASP.NET 网站如何集成QQ登录功能

参考了《asp.net 集成QQ2.0 登陆代码示例》和《登陆整合实现-QQ互联认证（ASP.NET版本）》。

using System;
using System.Net;
using System.Text;
using System.IO;
using System.Collections.Specialized;
using System.Data;
using System.Configuration;
using Newtonsoft.Json.Linq;
using Scratchline.Database;
using System.Web.Security;

namespace Scratchline.CN
{
    public partial class login_qq : System.Web.UI.Page
    {
        private static Random RndSeed = new Random();

        public string GenerateRndNonce()
        {
            return (RndSeed.Next(1, 0xf423f).ToString("000000") + RndSeed.Next(1, 0xf423f).ToString("000000"));
        }

        public string file_get_contents(string url, Encoding encode)
        {
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
            WebResponse response = request.GetResponse();
            using (MemoryStream ms = new MemoryStream())
            {
                using (Stream stream = response.GetResponseStream())
                {
                    int readc;
                    byte[] buffer = new byte[1024];
                    while ((readc = stream.Read(buffer, 0, buffer.Length)) > 0)
                    {
                        ms.Write(buffer, 0, readc);
                    }
                }
                return encode.GetString(ms.ToArray());
            }
        }
        NameValueCollection ParseUrlParameters(string str_params)
        {
            NameValueCollection nc = new NameValueCollection();
            foreach (string p in str_params.Split('&'))
            {
                string[] p_s = p.Split('=');
                nc.Add(p_s[0], p_s[1]);
            }
            return nc;
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            // 成功授权后的回调地址
            string redirect_uri = ConfigurationManager.AppSettings["redirect_uri"];
            // 分配给应用的appid
            string client_id = ConfigurationManager.AppSettings["client_id"];
            // 分配给网站的appkey
            string client_secret = ConfigurationManager.AppSettings["client_secret"];
            // 用户的OpenID
            string strOpenId = Request.QueryString["openid"] ?? string.Empty;

            if (strOpenId.Length <= 0)
            {
                //Step1：获取Authorization Code  
                string code = Request.QueryString["code"];
                if (string.IsNullOrEmpty(code))
                {
                    //state参数用于防止CSRF攻击，成功授权后回调时会原样带回  
                    Session["state"] = GenerateRndNonce();//md5(uniqid(rand(), TRUE));   
                    string authorize_uri = string.Format("https://graph.qq.com/oauth2.0/authorize?response_type=code&client_id={0}&redirect_uri={1}&state={2}", client_id, Server.UrlEncode(redirect_uri), Session["state"]);
                    Response.Redirect(authorize_uri);
                }
                //Step2：通过Authorization Code获取Access Token  
                if (Request["state"].ToString().Equals(Session["state"].ToString()))
                {
                    // 解析access_token返回包
                    string token_uri = string.Format("https://graph.qq.com/oauth2.0/token?grant_type=authorization_code&client_id={0}&client_secret={1}&code={2}&redirect_uri={3}", client_id, client_secret, code, redirect_uri);
                    string accesstoken = file_get_contents(token_uri, Encoding.UTF8);
                    NameValueCollection ps = ParseUrlParameters(accesstoken);
                    string access_token = ps["access_token"];
                    string expires_in = ps["expires_in"];
                    string refresh_token = ps["refresh_token"];

                    // 解析OpenID返回包
                    string me_uri = string.Format("https://graph.qq.com/oauth2.0/me?access_token={0}", access_token);
                    string callback = file_get_contents(me_uri, Encoding.UTF8);
                    if (callback.Contains("callback"))
                    {
                        int lpos = callback.IndexOf("(");
                        int rpos = callback.IndexOf(")");
                        callback = callback.Substring(lpos + 1, rpos - lpos - 1);
                    }
                    JObject jobject = JObject.Parse(callback);
                    string openid = jobject["openid"].ToString();

                    //Step4:通过access_token，appid，openid获得用户信息
                    string get_user_info_uri = string.Format("https://graph.qq.com/user/get_user_info?access_token={0}&oauth_consumer_key={1}&openid={2}", access_token, client_id, openid);
                    string user_info = file_get_contents(get_user_info_uri, Encoding.UTF8);
                    jobject = JObject.Parse(user_info);
                    Session["nickname"] = jobject["nickname"].ToString();
                    Session["figureurl_qq_2"] = jobject["figureurl_qq_2"].ToString();


                    string SQL = string.Format("SELECT * FROM _Users WHERE openid='{0}'", openid);
                    DataTable dt = SQLServer.Select(SQL);
                    if (dt.Rows.Count <= 0)
                    {
                        SQL = string.Format("INSERT INTO _Users([nickname],[openid]) VALUES('{0}','{1}')", Session["nickname"], openid);
                        SQLServer.Execute(SQL);
                    }
                    // 授权并跳转
                    FormsAuthentication.SetAuthCookie(openid, false);
                    Response.Redirect("index.aspx");
                }
            }
        }
    }
}