配置 OAuth 2.0 API 访问 Google 服务

创建 Google 开发者控制台项目以访问 API

在 Google 开发者控制台中创建项目是访问和使用 Google API 的关键步骤。此过程包括创建项目、同意条款、验证身份以及配置 API 设置以满足需求。以下步骤将指导您完成创建项目并获取 Calendar 和 Contacts API 等服务所需凭据的过程。

在 Google 开发者控制台中创建项目的步骤

  1. 访问链接 https://cloud.google.com/console/project 并使用您的 Gmail 凭据登录
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  1. 选中复选框 “I have read and agree to all Terms of Service for the Google Cloud Platform products.” 并点击 Create 按钮
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  1. 将请求 “SMS Verification”。点击继续按钮：
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  1. 输入您的国家名称和手机号码。点击按钮：发送验证码
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  1. 输入在手机上收到的验证码。
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  1. 在 APIs & auth \ APIs 列表中，打开 Calendar API 和 Contacts API 的状态，关闭其他所有 API。
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  1. 在 APIs & auth -> Credentials 中，点击 “OAuth” 部分下的 “CREAET NEW CLIENT ID” 按钮。选择 “Installed application” 并选择 “Other”，然后点击 “Create Client ID” 按钮。记录下此处的 Client ID 和 Client Secret，它们将在本节的示例代码中使用。
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安全的 Google OAuth 2.0 集成

在 Aspose.Email for .NET 中使用 Google OAuth 2.0 时，需要以下类：

  • GoogleOAuthHelper 类 - 简化了对 Google 用户进行身份验证并获取与 Google API（如 Calendar、Contacts、Gmail）交互所需令牌的过程。

  • GoogleUser 类 - 旨在封装和管理用户进行身份验证并与 Google 服务交互所需的凭据，特别是需要 OAuth 2.0 身份验证的 API，如 Google Calendar。

  • TokenResponse 类 - 该模型用于表示和处理来自 OAuth 2.0 令牌端点的响应数据，在此处可通过授权获取访问令牌。

在以下文章中，您将找到代码示例，演示如何在 .NET 环境中使用这些类，以建立与 OAuth 2.0 服务的安全交互。

使用 GoogleOAuthHelper 类进行 OAuth 2.0 身份验证

该类处理授权码 URL 的创建、代码挑战的生成以及访问令牌和刷新令牌的获取。通过使用 GoogleOAuthHelper，开发者可以简化 OAuth 2.0 流程，确保与 Google 服务的安全高效通信。以下代码片段展示了如何实现 GoogleOAuthHelper 类到项目中：

// For complete examples and data files, please go to https://github.com/aspose-email/Aspose.Email-for-.NET

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Security.Cryptography;
using System.Text;

/// <summary>
/// Developer console:
/// https://console.cloud.google.com/projectselector2
/// Documentation:
/// https://developers.google.com/identity/protocols/oauth2/native-app
/// </summary>
internal class GoogleOAuthHelper
{
    public const string AUTHORIZATION_URL = "https://accounts.google.com/o/oauth2/v2/auth";
    public const string TOKEN_REQUEST_URL = "https://oauth2.googleapis.com/token";

    public const string REDIRECT_URI = "urn:ietf:wg:oauth:2.0:oob";
    public const string REDIRECT_TYPE = "code";

    public static string codeVerifier;
    public static string codeChallenge;

    public static CodeChallengeMethod codeChallengeMethod = CodeChallengeMethod.S256;

    public const string SCOPE =
        "https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fcalendar" + // Calendar
        "+" +
        "https%3A%2F%2Fwww.google.com%2Fm8%2Ffeeds%2F" + // Contacts
        "+" +
        "https%3A%2F%2Fmail.google.com%2F"; // IMAP & SMTP

    static GoogleOAuthHelper()
    {
        CreateCodeVerifier();
        CreateCodeChallenge();
    }

    internal static string CreateCodeVerifier()
    {
        string allowedChars = "0123456789AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz-._~";

        const int minLength = 43;
        const int maxLength = 128;

        Random random = new Random();
        int length = minLength + random.Next(maxLength - minLength);
        List<char> codeVerifierChars = new List<char>();

        for (int i = 0; i < length; i++)
        {
            int index = random.Next(allowedChars.Length);
            codeVerifierChars.Add(allowedChars[index]);
        }

        return codeVerifier = string.Join("", codeVerifierChars.ToArray());
    }

    internal static string CreateCodeChallenge()
    {
        if (codeChallengeMethod == CodeChallengeMethod.Plain)
            return codeChallenge = codeVerifier;

        byte[] hashValue = null;
        using (SHA256 sha256 = SHA256.Create())
            hashValue = sha256.ComputeHash(Encoding.ASCII.GetBytes(codeVerifier));

        string b64 = Convert.ToBase64String(hashValue);
        b64 = b64.Split('=')[0];
        b64 = b64.Replace('+', '-');
        b64 = b64.Replace('/', '_');

        return codeChallenge = b64;
    }

    internal static string GetAuthorizationCodeUrl(GoogleUser user)
    {
        return GetAuthorizationCodeUrl(user, SCOPE, REDIRECT_URI, REDIRECT_TYPE);
    }

    internal static string GetAuthorizationCodeUrl(
        GoogleUser user, string scope, string redirectUri, string responseType)
    {
        string state = System.Web.HttpUtility.UrlEncode(Guid.NewGuid().ToString());

        string approveUrl = AUTHORIZATION_URL +
            $"?client_id={user.ClientId}&redirect_uri={redirectUri}&response_type={responseType}&scope={scope}&" +
            $"code_challenge={codeChallenge}&code_challenge_method={codeChallengeMethod.ToString()}&" +
            $"state={state}";

        return approveUrl;
    }

    internal static TokenResponse GetAccessTokenByRefreshToken(GoogleUser user)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(TOKEN_REQUEST_URL);
        request.CookieContainer = new CookieContainer();
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";

        string clientId = System.Web.HttpUtility.UrlEncode(user.ClientId);
        string clientSecret = System.Web.HttpUtility.UrlEncode(user.ClientSecret);
        string refreshToken = System.Web.HttpUtility.UrlEncode(user.RefreshToken);
        string grantType = System.Web.HttpUtility.UrlEncode("refresh_token");

        string encodedParameters = $"client_id={clientId}&client_secret={clientSecret}&refresh_token={refreshToken}&grant_type={grantType}";

        byte[] requestData = Encoding.UTF8.GetBytes(encodedParameters);
        request.ContentLength = requestData.Length;
        if (requestData.Length > 0)
            using (Stream stream = request.GetRequestStream())
                stream.Write(requestData, 0, requestData.Length);

        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        string responseText = null;
        using (TextReader reader = new StreamReader(response.GetResponseStream(), Encoding.ASCII))
            responseText = reader.ReadToEnd();

        TokenResponse tokensResponse = JsonConvert.DeserializeObject<TokenResponse>(responseText);

        return tokensResponse;
    }

    internal static TokenResponse GetAccessTokenByAuthCode(string authorizationCode, GoogleUser user)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(TOKEN_REQUEST_URL);
        request.CookieContainer = new CookieContainer();
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";

        string clientId = System.Web.HttpUtility.UrlEncode(user.ClientId);
        string clientSecret = System.Web.HttpUtility.UrlEncode(user.ClientSecret);
        string authCode = System.Web.HttpUtility.UrlEncode(authorizationCode);
        string redirectUri = System.Web.HttpUtility.UrlEncode(REDIRECT_URI);
        string grantType = System.Web.HttpUtility.UrlEncode("authorization_code");

        string encodedParameters = $"client_id={clientId}&client_secret={clientSecret}&code={authCode}&code_verifier={codeVerifier}&redirect_uri={redirectUri}&grant_type={grantType}";

        byte[] requestData = Encoding.UTF8.GetBytes(encodedParameters);
        request.ContentLength = requestData.Length;
        if (requestData.Length > 0)
            using (Stream stream = request.GetRequestStream())
                stream.Write(requestData, 0, requestData.Length);

        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        string responseText = null;
        using (TextReader reader = new StreamReader(response.GetResponseStream(), Encoding.ASCII))
            responseText = reader.ReadToEnd();

        TokenResponse tokensResponse = JsonConvert.DeserializeObject<TokenResponse>(responseText);

        return tokensResponse;
    }

    public enum CodeChallengeMethod
    {
        S256,
        Plain
    }
}

Google OAuth Helper 应按如下方式使用：

  1. 首先需要生成授权码 URL。
  2. 在浏览器中打开 URL 并完成所有操作。随后，您将收到授权码。
  3. 使用授权码获取刷新令牌。
  4. 当刷新令牌存在时，可使用它检索访问令牌。
GoogleUser user = new GoogleUser(email, password, clientId, clientSecret);

string authUrl = GoogleOAuthHelper.GetAuthorizationCodeUrl(user);

Console.WriteLine("Go to the following URL and get your authorization code:");
Console.WriteLine(authUrl);
Console.WriteLine();

Console.WriteLine("Enter the authorization code:");
string authorizationCode = Console.ReadLine();
Console.WriteLine();

TokenResponse tokenInfo = GoogleOAuthHelper.GetAccessTokenByAuthCode(authorizationCode, user);
Console.WriteLine("The refresh token has been received:");
Console.WriteLine(tokenInfo.RefreshToken);
Console.WriteLine();

user.RefreshToken = tokenInfo.RefreshToken;
tokenInfo = GoogleOAuthHelper.GetAccessTokenByRefreshToken(user);
Console.WriteLine("The new access token has been received:");
Console.WriteLine(tokenInfo.AccessToken);
Console.WriteLine();

OAuth 2.0 身份验证的 GoogleUser 类

以下代码片段展示了如何实现 GoogleUser 类：

// For complete examples and data files, please go to https://github.com/aspose-email/Aspose.Email-for-.NET

public class GoogleUser
{
    public GoogleUser(string email, string password, string clientId, string clientSecret)
        : this(email, password, clientId, clientSecret, null)
    {
    }

    public GoogleUser(string email, string password, string clientId, string clientSecret, string refreshToken)
    {
        Email = email;
        Password = password;
        ClientId = clientId;
        ClientSecret = clientSecret;
        RefreshToken = refreshToken;
    }

    public readonly string Email;
    public readonly string Password;
    public readonly string ClientId;
    public readonly string ClientSecret;

    public string RefreshToken;
}

使用 TokenResponse 类进行 OAuth 2.0 身份验证

以下代码片段展示了如何 TokenResponse 可以实现类：

// For complete examples and data files, please go to https://github.com/aspose-email/Aspose.Email-for-.NET

using Newtonsoft.Json;

public class TokenResponse
{
    [JsonProperty(NullValueHandling = NullValueHandling.Ignore, PropertyName = "access_token", Required = Required.Default)]
    public string AccessToken { get; set; }

    [JsonProperty(NullValueHandling = NullValueHandling.Ignore, PropertyName = "token_type", Required = Required.Default)]
    public string TokenType { get; set; }

    [JsonProperty(NullValueHandling = NullValueHandling.Ignore, PropertyName = "expires_in", Required = Required.Default)]
    public int ExpiresIn { get; set; }

    [JsonProperty(NullValueHandling = NullValueHandling.Ignore, PropertyName = "refresh_token", Required = Required.Default)]
    public string RefreshToken { get; set; }

    [JsonProperty(NullValueHandling = NullValueHandling.Ignore, PropertyName = "scope", Required = Required.Default)]
    public string Scope { get; set; }
}
.NET 应用程序中的 Google 日历管理