C# Language
Importar contactos de Google

Observaciones

Requerimientos

Para importar contactos de Google (Gmail) en la aplicación MVC de ASP.NET, primero descargue "Configuración de API de Google". Esto le otorgará las siguientes referencias:

using Google.Contacts;
using Google.GData.Client;
using Google.GData.Contacts;
using Google.GData.Extensions;

Añadir estos a la aplicación correspondiente.

Código fuente en el controlador

using Google.Contacts;
using Google.GData.Client;
using Google.GData.Contacts;
using Google.GData.Extensions;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Web;
using System.Web.Mvc;

namespace GoogleContactImport.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

        public ActionResult Import()
        {
            string clientId = "";  // here you need to add your google client id
            string redirectUrl = "http://localhost:1713/Home/AddGoogleContacts"; // here your redirect action method NOTE: you need to configure same url in google console
            Response.Redirect("https://accounts.google.com/o/oauth2/auth?redirect_uri=" + redirectUrl + "&amp&response_type=code&amp&client_id=" + clientId + "&amp&scope=https://www.google.com/m8/feeds/&approval_prompt=force&access_type=offline");
            return View();
        }

        public ActionResult AddGoogleContacts()
        {
            string code = Request.QueryString["code"];
            if (!string.IsNullOrEmpty(code))
            {
                var contacts = GetAccessToken().ToArray();
                if (contacts.Length > 0)
                {
                  // You will get all contacts here
                    return View("Index",contacts);
                }
                else
                {
                    return RedirectToAction("Index","Home");
                }
            }
            else
            {
                return RedirectToAction("Index", "Home");
            }
        }
        public List<GmailContacts> GetAccessToken()
        {
            string code = Request.QueryString["code"];
            string google_client_id = ""; //your google client Id
            string google_client_sceret = ""; // your google secret key
            string google_redirect_url = "http://localhost:1713/MyContact/AddGoogleContacts";


            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create("https://accounts.google.com/o/oauth2/token");
            webRequest.Method = "POST";
            string parameters = "code=" + code + "&client_id=" + google_client_id + "&client_secret=" + google_client_sceret + "&redirect_uri=" + google_redirect_url + "&grant_type=authorization_code";
            byte[] byteArray = Encoding.UTF8.GetBytes(parameters);
            webRequest.ContentType = "application/x-www-form-urlencoded";
            webRequest.ContentLength = byteArray.Length;
            Stream postStream = webRequest.GetRequestStream();
            // Add the post data to the web request
            postStream.Write(byteArray, 0, byteArray.Length);
            postStream.Close();
            WebResponse response = webRequest.GetResponse();
            postStream = response.GetResponseStream();
            StreamReader reader = new StreamReader(postStream);
            string responseFromServer = reader.ReadToEnd();
            GooglePlusAccessToken serStatus = JsonConvert.DeserializeObject<GooglePlusAccessToken>(responseFromServer);
            /*End*/
            return GetContacts(serStatus);
        }

        public List<GmailContacts> GetContacts(GooglePlusAccessToken serStatus)
        {
            string google_client_id = "";  //client id
            string google_client_sceret = ""; //secret key
            /*Get Google Contacts From Access Token and Refresh Token*/
            // string refreshToken = serStatus.refresh_token;
            string accessToken = serStatus.access_token;
            string scopes = "https://www.google.com/m8/feeds/contacts/default/full/";
            OAuth2Parameters oAuthparameters = new OAuth2Parameters()
            {
                ClientId = google_client_id,
                ClientSecret = google_client_sceret,
                RedirectUri = "http://localhost:1713/Home/AddGoogleContacts",
                Scope = scopes,
                AccessToken = accessToken,
                //  RefreshToken = refreshToken
            };

            RequestSettings settings = new RequestSettings("App Name", oAuthparameters);
            ContactsRequest cr = new ContactsRequest(settings);
            ContactsQuery query = new ContactsQuery(ContactsQuery.CreateContactsUri("default"));
            query.NumberToRetrieve = 5000;
            Feed<Contact> ContactList = cr.GetContacts();

            List<GmailContacts> olist = new List<GmailContacts>();
            foreach (Contact contact in ContactList.Entries)
            {
                foreach (EMail email in contact.Emails)
                {
                    GmailContacts gc = new GmailContacts();
                    gc.EmailID = email.Address;
                    var a = contact.Name.FullName;
                    olist.Add(gc);
                }
            }
            return olist;
        }

        public class GmailContacts
        {
            public string EmailID
            {
                get { return _EmailID; }
                set { _EmailID = value; }
            }
            private string _EmailID;
        }

        public class GooglePlusAccessToken
        {

            public GooglePlusAccessToken()
            { }


            public string access_token
            {
                get { return _access_token; }
                set { _access_token = value; }
            }
            private string _access_token;

            public string token_type
            {
                get { return _token_type; }
                set { _token_type = value; }
            }
            private string _token_type;

            public string expires_in
            {
                get { return _expires_in; }
                set { _expires_in = value; }
            }
            private string _expires_in;

        }
    }
}

Código fuente en la vista.

El único método de acción que necesita agregar es agregar un enlace de acción presente a continuación

<a href='@Url.Action("Import", "Home")'>Import Google Contacts</a>