android - facebook android sdk - 用户电子邮件返回空

Question

我有以下代码让用户通过我的应用程序登录到 facebook。我第一次将 user.getproperty("email") 设置为 null。当我第二次运行该应用程序时，我得到了值(value)。下面是我的代码。

私有(private)无效 loginToFb() {

    final Session.NewPermissionsRequest newPermissionsRequest = new Session.NewPermissionsRequest(
            LandingPageActivity.this, Arrays.asList(
                    "user_location", "user_birthday",
                    "user_likes", "email"));
    Session.openActiveSession(this, true, new Session.StatusCallback() {

        // callback when session changes state
        @Override
        public void call(Session session, SessionState state,
                Exception exception) {
            if (session.isOpened()) {
                session.requestNewReadPermissions(newPermissionsRequest);
                // make request to the /me API
                Request request = Request.newMeRequest(session,
                        new Request.GraphUserCallback() {

                            // callback after Graph API response with user
                            // object
                            @Override
                            public void onCompleted(GraphUser user,
                                    Response response) {
                                if (user != null) {
                                    fetchUserFbDetails(user);
                                }
                            }

                        });
                Request.executeBatchAsync(request);

            }

        }
    });

}

Answer 1

您不应自己管理 session ，而应使用 Facebook 的 LoginButton 和 UiLifecycleHelper。

1) 在您的 UI 中声明一个 LoginButton:

<!-- FACEBOOK LOGIN -->
<com.facebook.widget.LoginButton
    android:id="@+id/facebookLoginBtn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true" />

2) 创建一个 LoginFragment 并声明一个私有(private)成员:

private UiLifecycleHelper mFacebookLifecycleHelper;

3)在Fragment的onCreate()方法中，初始化LoginButton并添加一个钩子(Hook)来获取用户信息:

LoginButton facebookLoginButton = (LoginButton) view.findViewById(R.id.facebookLoginBtn);
facebookLoginButton.setFragment(this);

// Intercept the facebook user returned from login
facebookLoginButton.setUserInfoChangedCallback(new LoginButton.UserInfoChangedCallback() {

    @Override
    public void onUserInfoFetched(GraphUser user) {
        mFacebookUser = user;

        if (user != null) {
            LogUtils.LOGFB(TAG, "Got a Facebook user: " + user.getFirstName() +
                    " " + user.getLastName() + ", email: " + user.getProperty("email"));
        }
        else {
            LogUtils.LOGFB(TAG, "No Facebook user");
        }
    }
});

// Set extra read permissions
facebookLoginButton.setReadPermissions(Arrays.asList(
        "email", "user_birthday", ...));

4) 创建回调以监听 Facebook session 状态的变化:

// Listen for changes in Facebook session state
private Session.StatusCallback callback = new Session.StatusCallback() {
    @Override
    public void call(Session session, SessionState state, Exception exception) {
        onSessionStateChange(session, state, exception);
    }
};

// Respond to Facebook session state changes
private void onSessionStateChange(Session session, SessionState state, Exception exception) {
    if (state.isOpened()) {
        LogUtils.LOGFB(TAG, "Logged in using facebook");
        LogUtils.LOGFB(TAG, "Access Token: " + session.getAccessToken());
        // TODO: display authenticated UI
    } else if (state.isClosed()) {
        LogUtils.LOGFB(TAG, "Logged out from facebook");
        // TODO: display the non-authenticated UI
    }
}

5) 然后确保为 fragment 的所有生命周期更改调用 lifecycleHelper:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Creates the Facebook session and opens it automatically if a cached token is available.
    mFacebookLifecycleHelper = new UiLifecycleHelper(getActivity(), callback);
    mFacebookLifecycleHelper.onCreate(savedInstanceState);
    ...
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    mFacebookLifecycleHelper.onActivityResult(requestCode, resultCode, data);
}

@Override
public void onResume() {
    super.onResume();
    mFacebookLifecycleHelper.onResume();
}
@Override
public void onPause() {
    super.onPause();
    mFacebookLifecycleHelper.onPause();
}

@Override
public void onDestroy() {
    mFacebookLifecycleHelper.onDestroy();
    super.onDestroy();
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    mFacebookLifecycleHelper.onSaveInstanceState(outState);
}