使用 OAUTH 2.0 验证并从 Facebook cookie 获取数据

我有一个用 GWT 制作的网页。在那里，我使用所有登录 facebook 的东西和一个受操纵的 gwtfb 库，一切正常。迁移到 oauth 2.0 后，发送到服务器的 cookie 已更改为加密的 cookie。

我想要一个java示例代码来实现在服务器中与旧的相同：

• 我需要像使用 cookie md5 技巧之前那样验证调用，以了解调用是否是由我的客户端页面进行的。
• 从该 cookie 获取数据：我需要 Facebook 用户。

如果可能的话不调用FB，只使用cookie数据。

提前致谢。

好吧，虽然我有一些很好的答案，但我还是用我在博客中写的内容来回答自己：http://pablocastilla.wordpress.com/2011/09/25/how-to-implement-oauth-f/ http://pablocastilla.wordpress.com/2011/09/25/how-to-implement-oauth-f/

现在cookie发生了很大的变化：它被加密了，没有accesstoken，而且它的内容格式也发生了很大的变化。这里有一些讨论它的链接：

http://developers.facebook.com/docs/authentication/signed_request/ http://developers.facebook.com/docs/authentication/signed_request/

http://developers.facebook.com/docs/authentication/ http://developers.facebook.com/docs/authentication/

http://blog.sociablelabs.com/2011/09/19/server-side-changes-facebook-oauth-2-0-upgrade/ http://blog.sociablelabs.com/2011/09/19/server-side-changes-facebook-oauth-2-0-upgrade/

因此，要验证 cookie、从中获取用户并获取访问令牌，您可以使用以下代码：

public class FaceBookSecurity {

// return the fb user in the cookie.
public static String getFBUserFromCookie(HttpServletRequest request)
        throws Exception {
    Cookie fbCookie = getFBCookie(request);

    if (fbCookie == null)
        return null;

    // gets cookie value
    String fbCookieValue = fbCookie.getValue();

    // splits it.
    String[] stringArgs = fbCookieValue.split("\\.");
    String encodedPayload = stringArgs[1];

    String payload = base64UrlDecode(encodedPayload);

    // gets the js object from the cookie
    JsonObject data = new JsonObject(payload);

    return data.getString("user_id");

}

public static boolean ValidateFBCookie(HttpServletRequest request)
        throws Exception {

    Cookie fbCookie = getFBCookie(request);

    if (fbCookie == null)
        throw new NotLoggedInFacebookException();

    // gets cookie information
    String fbCookieValue = fbCookie.getValue();

    String[] stringArgs = fbCookieValue.split("\\.");
    String encodedSignature = stringArgs[0];
    String encodedPayload = stringArgs[1];

    //decode
    String sig = base64UrlDecode(encodedSignature);
    String payload = base64UrlDecode(encodedPayload);

    // gets the js object from the cookie
    JsonObject data = new JsonObject(payload);

    if (!data.getString("algorithm").Equals("HMAC-SHA256")) {
        return false;
    }

    SecretKey key = new SecretKeySpec(
            ApplicationServerConstants.FacebookSecretKey.getBytes(),
            "hmacSHA256");

    Mac hmacSha256 = Mac.getInstance("hmacSHA256");
    hmacSha256.init(key);
    // decode the info.
    byte[] mac = hmacSha256.doFinal(encodedPayload.getBytes());

    String expectedSig = new String(mac);

    // compare if the spected sig is the same than in the cookie.
    return expectedSig.equals(sig);

}

public static String getFBAccessToken(HttpServletRequest request)
        throws Exception {
    Cookie fbCookie = getFBCookie(request);

    String fbCookieValue = fbCookie.getValue();

    String[] stringArgs = fbCookieValue.split("\\.");
    String encodedPayload = stringArgs[1];

    String payload = base64UrlDecode(encodedPayload);

    // gets the js object from the cookie
    JsonObject data = new JsonObject(payload);

    String authUrl = getAuthURL(data.getString("code"));
    URL url = new URL(authUrl);
    URI uri = new URI(url.getProtocol(), url.getHost(), url.getPath(),
            url.getQuery(), null);
    String result = readURL(uri.toURL());

    String[] resultSplited = result.split("&");

    return resultSplited[0].split("=")[1];

}

// creates the url for calling to oauth.
public static String getAuthURL(String authCode) {
    String url = "https://graph.facebook.com/oauth/access_token?client_id="
            + ApplicationConstants.FacebookApiKey
            + "&redirect_uri=&client_secret="
            + ApplicationServerConstants.FacebookSecretKey + "&code="
            + authCode;

    return url;
}

// reads the url.
private static String readURL(URL url) throws IOException {

    InputStream is = url.openStream();

    InputStreamReader inStreamReader = new InputStreamReader(is);
    BufferedReader reader = new BufferedReader(inStreamReader);

    String s = "";

    int r;
    while ((r = is.read()) != -1) {
        s = reader.readLine();
    }

    reader.close();
    return s;
}

private static String base64UrlDecode(String input) {
    String result = null;
    Base64 decoder = new Base64(true);
    byte[] decodedBytes = decoder.decode(input);
    result = new String(decodedBytes);
    return result;
}

    private static Cookie getFBCookie(HttpServletRequest request) 
    {
        Cookie[] cookies = request.getCookies();

        if (cookies == null)
            return null;

        Cookie fbCookie = null;

        for (Cookie c : cookies) {
            if (c.getName().equals(
                "fbsr_" + ApplicationServerConstants.FacebookApiKey)) {
                fbCookie = c;
            }
        }
        return fbCookie;
    }
}