C# 在我的C windows窗体应用程序中检查Gmail登录credentails？

我已经开始使用windows窗体创建一个小应用程序，其中用户可以从他们的gmail帐户发送电子邮件，当用户在我的登录表单1中输入正确的登录凭据时，我可以发送邮件，但如果他在登录表单1中输入了错误的凭据，它进入我的邮件表单2并显示错误，因此我想检查Gmail登录凭据..请帮助我获取代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Mail;

namespace first
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Form1 a = new Form1();
            this.Hide();
            a.ShowDialog();
            this.Close();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            SmtpClient client = new SmtpClient("smtp.gmail.com", 587);
            client.Credentials = new NetworkCredential(Form3.tb.Text, Form3.tb1.Text);
            MailMessage msg = new MailMessage();
            msg.To.Add(new MailAddress(To.Text));
            msg.From = new MailAddress(From.Text);
            msg.Subject = Sub.Text;
            msg.Body = Body.Text;
            client.EnableSsl = true; //for security in gmail,https kind of
            client.Send(msg);
            try
            {
                MessageBox.Show("Mail sent successfully", "Praveen Mail");
            }
            catch (Exception ex)
            {
                MessageBox.Show("Mail Sending Failed Due to" + ex.Message, "Praveen Mail");
            }

        }

    }
}

---

谷歌提供了一个可以解决你问题的.NETAPI

-----编辑----

步骤1：注册使用谷歌api。它是免费的，上面的链接描述了这样做的过程

using System;
using System.Diagnostics;
using DotNetOpenAuth.OAuth2;
using Google.Apis.Authentication.OAuth2;
using Google.Apis.Authentication.OAuth2.DotNetOpenAuth;
using Google.Apis.Samples.Helper;
using Google.Apis.Tasks.v1;
using Google.Apis.Tasks.v1.Data;
using Google.Apis.Util;

namespace Google.Apis.Samples.TasksOAuth2
{
    /// <summary>
    /// This sample demonstrates the simplest use case for an OAuth2 service. 
    /// The schema provided here can be applied to every request requiring   authentication.
    /// </summary>
    public class Program
    {
    public static void Main(string[] args)
    {
        // Display the header and initialize the sample.
        CommandLine.EnableExceptionHandling();
        CommandLine.DisplayGoogleSampleHeader("Tasks API");

        // Register the authenticator.
        var provider = new NativeApplicationClient(GoogleAuthenticationServer.Description);
        provider.ClientIdentifier = "<client id>";
        provider.ClientSecret = "<client secret>";
        var auth = new OAuth2Authenticator<NativeApplicationClient>(provider, GetAuthorization);

        // Create the service.
        var service = new TasksService(auth);
        TaskLists results = service.Tasklists.List().Fetch();
        Console.WriteLine("Lists:");
        foreach (TaskList list in results.Items)
        {
            Console.WriteLine("- " + list.Title);
        }
        Console.ReadKey();
    }

    private static IAuthorizationState GetAuthorization(NativeApplicationClient arg)
    {
        // Get the auth URL:
        IAuthorizationState state = new AuthorizationState(new[] { TasksService.Scopes.Tasks.GetStringValue() });
        state.Callback = new Uri(NativeApplicationClient.OutOfBandCallbackUrl);
        Uri authUri = arg.RequestUserAuthorization(state);

        // Request authorization from the user (by opening a browser window):
        Process.Start(authUri.ToString());
        Console.Write("  Authorization Code: ");
        string authCode = Console.ReadLine();
        Console.WriteLine();

        // Retrieve the access token by using the authorization code:
        return arg.ProcessUserAuthorization(authCode, state);
    }
}

步骤2：实现下面的代码。我从上面的链接借用了它

using System;
using System.Diagnostics;
using DotNetOpenAuth.OAuth2;
using Google.Apis.Authentication.OAuth2;
using Google.Apis.Authentication.OAuth2.DotNetOpenAuth;
using Google.Apis.Samples.Helper;
using Google.Apis.Tasks.v1;
using Google.Apis.Tasks.v1.Data;
using Google.Apis.Util;

namespace Google.Apis.Samples.TasksOAuth2
{
    /// <summary>
    /// This sample demonstrates the simplest use case for an OAuth2 service. 
    /// The schema provided here can be applied to every request requiring   authentication.
    /// </summary>
    public class Program
    {
    public static void Main(string[] args)
    {
        // Display the header and initialize the sample.
        CommandLine.EnableExceptionHandling();
        CommandLine.DisplayGoogleSampleHeader("Tasks API");

        // Register the authenticator.
        var provider = new NativeApplicationClient(GoogleAuthenticationServer.Description);
        provider.ClientIdentifier = "<client id>";
        provider.ClientSecret = "<client secret>";
        var auth = new OAuth2Authenticator<NativeApplicationClient>(provider, GetAuthorization);

        // Create the service.
        var service = new TasksService(auth);
        TaskLists results = service.Tasklists.List().Fetch();
        Console.WriteLine("Lists:");
        foreach (TaskList list in results.Items)
        {
            Console.WriteLine("- " + list.Title);
        }
        Console.ReadKey();
    }

    private static IAuthorizationState GetAuthorization(NativeApplicationClient arg)
    {
        // Get the auth URL:
        IAuthorizationState state = new AuthorizationState(new[] { TasksService.Scopes.Tasks.GetStringValue() });
        state.Callback = new Uri(NativeApplicationClient.OutOfBandCallbackUrl);
        Uri authUri = arg.RequestUserAuthorization(state);

        // Request authorization from the user (by opening a browser window):
        Process.Start(authUri.ToString());
        Console.Write("  Authorization Code: ");
        string authCode = Console.ReadLine();
        Console.WriteLine();

        // Retrieve the access token by using the authorization code:
        return arg.ProcessUserAuthorization(authCode, state);
    }
}

---

}

首先，请您向我们展示您当前拥有的代码。一般来说，如果登录失败，你应该得到Gmail的回复，并将其显示给用户。我已经添加了我的代码，请检查一下。你能详细说明我如何在我的表单代码中使用它吗。我不熟悉表格，所以..@praveen-网站上有一些例子。使用Microsoft OAuth SDK将Google的SDK实现到桌面应用程序中。@praveen-粘贴了我上面粘贴的链接中的一些示例代码。但是拉姆霍恩是对的。。。都在网站上。