要获得电子邮件访问权限，您需要编写自定义 Facebook 提供商。
下载DotNetOpenAuth.AspNet.Clients.FacebookClient并添加{ "scope", "email, read_stream" }，
public sealed class CustomFacebookClient : OAuth2Client
{
#region Constants and Fields
/// <summary>
/// The authorization endpoint.
/// </summary>
private const string AuthorizationEndpoint = "https://www.facebook.com/dialog/oauth";
/// <summary>
/// The token endpoint.
/// </summary>
private const string TokenEndpoint = "https://graph.facebook.com/oauth/access_token";
/// <summary>
/// The _app id.
/// </summary>
private readonly string appId;
/// <summary>
/// The _app secret.
/// </summary>
private readonly string appSecret;
#endregion
#region Constructors and Destructors
/// <summary>
/// Initializes a new instance of the <see cref="FacebookClient"/> class.
/// </summary>
/// <param name="appId">
/// The app id.
/// </param>
/// <param name="appSecret">
/// The app secret.
/// </param>
public CustomFacebookClient(string appId, string appSecret)
: base("facebook")
{
Requires.NotNullOrEmpty(appId, "appId");
Requires.NotNullOrEmpty(appSecret, "appSecret");
this.appId = appId;
this.appSecret = appSecret;
}
#endregion
#region Methods
/// <summary>
/// The get service login url.
/// </summary>
/// <param name="returnUrl">
/// The return url.
/// </param>
/// <returns>An absolute URI.</returns>
protected override Uri GetServiceLoginUrl(Uri returnUrl)
{
// Note: Facebook doesn't like us to url-encode the redirect_uri value
var builder = new UriBuilder(AuthorizationEndpoint);
builder.AppendQueryArgs(
new Dictionary<string, string> {
{ "client_id", this.appId },
{ "scope", "email, read_stream" },
{ "redirect_uri", returnUrl.AbsoluteUri }
});
return builder.Uri;
}
/// <summary>
/// The get user data.
/// </summary>
/// <param name="accessToken">
/// The access token.
/// </param>
/// <returns>A dictionary of profile data.</returns>
protected override IDictionary<string, string> GetUserData(string accessToken)
{
FacebookGraphData graphData;
var request =
WebRequest.Create(
"https://graph.facebook.com/me?access_token=" + FacebookClientHelper.EscapeUriDataStringRfc3986(accessToken));
using (var response = request.GetResponse())
{
using (var responseStream = response.GetResponseStream())
{
graphData = FacebookClientHelper.Deserialize<FacebookGraphData>(responseStream);
}
}
// this dictionary must contains
var userData = new Dictionary<string, string>();
userData.AddItemIfNotEmpty("id", graphData.Id);
userData.AddItemIfNotEmpty("username", graphData.Email);
userData.AddItemIfNotEmpty("name", graphData.Name);
userData.AddItemIfNotEmpty("link", graphData.Link == null ? null : graphData.Link.AbsoluteUri);
userData.AddItemIfNotEmpty("gender", graphData.Gender);
userData.AddItemIfNotEmpty("birthday", graphData.Birthday);
userData.AddItemIfNotEmpty("email", graphData.Email);
return userData;
}
/// <summary>
/// Obtains an access token given an authorization code and callback URL.
/// </summary>
/// <param name="returnUrl">
/// The return url.
/// </param>
/// <param name="authorizationCode">
/// The authorization code.
/// </param>
/// <returns>
/// The access token.
/// </returns>
protected override string QueryAccessToken(Uri returnUrl, string authorizationCode)
{
// Note: Facebook doesn't like us to url-encode the redirect_uri value
var builder = new UriBuilder(TokenEndpoint);
builder.AppendQueryArgs(
new Dictionary<string, string> {
{ "client_id", this.appId },
{ "redirect_uri", NormalizeHexEncoding(returnUrl.AbsoluteUri) },
{ "client_secret", this.appSecret },
{ "code", authorizationCode },
});
using (WebClient client = new WebClient())
{
string data = client.DownloadString(builder.Uri);
if (string.IsNullOrEmpty(data))
{
return null;
}
var parsedQueryString = HttpUtility.ParseQueryString(data);
return parsedQueryString["access_token"];
}
}
/// <summary>
/// Converts any % encoded values in the URL to uppercase.
/// </summary>
/// <param name="url">The URL string to normalize</param>
/// <returns>The normalized url</returns>
/// <example>NormalizeHexEncoding("Login.aspx?ReturnUrl=%2fAccount%2fManage.aspx") returns "Login.aspx?ReturnUrl=%2FAccount%2FManage.aspx"</example>
/// <remarks>
/// There is an issue in Facebook whereby it will rejects the redirect_uri value if
/// the url contains lowercase % encoded values.
/// </remarks>
private static string NormalizeHexEncoding(string url)
{
var chars = url.ToCharArray();
for (int i = 0; i < chars.Length - 2; i++)
{
if (chars[i] == '%')
{
chars[i + 1] = char.ToUpperInvariant(chars[i + 1]);
chars[i + 2] = char.ToUpperInvariant(chars[i + 2]);
i += 2;
}
}
return new string(chars);
}
#endregion
}
此外，人们可能会认为这可行：
var parameters = new Dictionary<string, object>();
parameters["scope"] = "email";
OAuthWebSecurity.RegisterFacebookClient(appId: "appId", appSecret: "appSecret",
"facebook, parameters);
这行不通。它为您的提供者提供了额外的数据，当您在视图中展示您的提供者时可以使用这些数据。
<img src="@provder.ExtraData["icon"]"/>