以下是一个使用ASP.NET Core调用Google API获取联系人或电子邮件的解决方案，包含代码示例：

首先，确保你已经安装了必要的NuGet包：

1. Google.Apis
2. Google.Apis.Auth
3. Google.Apis.Auth.AspNetCore3
4. Google.Apis.PeopleService

接下来，你需要在Google Cloud控制台中创建一个新的OAuth 2.0客户端ID，并设置正确的重定向URL。

在Startup.cs文件中，添加以下代码：

using Google.Apis.Auth.AspNetCore3;
using Google.Apis.PeopleService.v1;

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllersWithViews();
    
    services
        .AddAuthentication(o =>
        {
            // This forces challenge results to be handled by Google OpenID Handler, so there's no
            // need to add an AccountController that emits challenges for Login.
            o.DefaultChallengeScheme = GoogleOpenIdConnectDefaults.AuthenticationScheme;
            // This forces forbid results to be handled by Google OpenID Handler, which checks if
            // extra scopes are required and does automatic incremental auth.
            o.DefaultForbidScheme = GoogleOpenIdConnectDefaults.AuthenticationScheme;
            // Default scheme that will handle everything else.
            // Once a user is authenticated, the OAuth2 token info is stored in cookies.
            o.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
        })
        .AddGoogleOpenIdConnect(options =>
        {
            // You must create a client ID in the Google API Console and configure the callback URL.
            options.ClientId = Configuration["Google:ClientId"];
            options.ClientSecret = Configuration["Google:ClientSecret"];
            options.Scope.Add("openid email");
            options.SaveTokens = true;
            options.Events.OnCreatingTicket = context =>
            {
                // Store the access token and the user identity in cookies for further use.
                var accessToken = context.AccessToken;
                context.Properties.StoreTokens(new[]
                {
                    new AuthenticationToken { Name = "access_token", Value = accessToken }
                });

                return Task.CompletedTask;
            };
        });

    services.AddAuthorization(options =>
    {
        options.FallbackPolicy = new AuthorizationPolicyBuilder()
            .RequireAuthenticatedUser()
            .Build();
    });

    services.AddHttpClient();
    services.AddHttpContextAccessor();
    services.AddTransient();
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // ...

    app.UseHttpsRedirection();
    app.UseStaticFiles();
    app.UseRouting();

    app.UseAuthentication();
    app.UseAuthorization();

    // ...
}

在Controller中，你可以使用以下代码来调用Google API并获取联系人或电子邮件：

using Google.Apis.Auth.AspNetCore3;
using Google.Apis.PeopleService.v1;

public class HomeController : Controller
{
    private readonly PeopleServiceService _peopleService;

    public HomeController(PeopleServiceService peopleService)
    {
        _peopleService = peopleService;
    }

    public async Task Index()
    {
        var user = await HttpContext.GetIdentityUserAsync();
        
        var request = _peopleService.People.Connections.List("people/me");
        request.RequestMaskIncludeField = "person.names,person.email_addresses";
        
        var response = await request.ExecuteAsync();
        var connections = response.Connections;
        
        // 处理联系人或电子邮件
        
        return View();
    }
}

这是一个基本的示例，你可以根据你的需求进行修改和扩展。