如何在Android中为您的应用程序启用默认Facebook应用程序登录会话？

Question

我想让Facebook从我的应用程序登录，我成功完成了。但我想，如果我的设备中的Facebook默认应用程序已经登录，那么它将自动登录我的应用程序。

我无法理解如何获得默认的Facebook登录会话。如果有人有任何想法，请与我分享。有没有办法通过设备信息获取Facebook信息？

我被困在这上面了。提前谢谢。

我使用了这段代码：AM我是正确的方式吗？还是需要使用其他代码？请建议我..

private void signInWithFacebook() {

        SessionTracker mSessionTracker = new SessionTracker(getBaseContext(), new StatusCallback() {

            @Override
            public void call(Session session, SessionState state, Exception exception) {
            }
        }, null, false);

        String applicationId = getResources().getString(R.string.applicationId);
        mCurrentSession = mSessionTracker.getSession();

        if (mCurrentSession == null || mCurrentSession.getState().isClosed()) {
            mSessionTracker.setSession(null);
            Session session = new Session.Builder(getBaseContext()).setApplicationId(applicationId).build();
            Session.setActiveSession(session);
            mCurrentSession = session;
        }

        if (!mCurrentSession.isOpened()) {
            Session.OpenRequest openRequest = null;
            openRequest = new Session.OpenRequest(LoginActivity.this);

            if (openRequest != null) {
                openRequest.setDefaultAudience(SessionDefaultAudience.FRIENDS);
                openRequest.setPermissions(Arrays.asList("offline_access", "publish_stream", "user_photos", "publish_checkins", "email"));
                openRequest.setLoginBehavior(SessionLoginBehavior.SSO_WITH_FALLBACK);

                mCurrentSession.openForRead(openRequest);
            }
        }else {
            Request.executeMeRequestAsync(mCurrentSession, new Request.GraphUserCallback() {
                @Override
                public void onCompleted(GraphUser user, Response response) {
                    Log.w("myConsultant", user.getId() + " " + user.getName() + " " + user.getInnerJSONObject());
                }
            });
        }
    }






public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Session.getActiveSession().onActivityResult(this, requestCode, resultCode, data);

        if (mCurrentSession.isOpened()) {
            Request.executeMeRequestAsync(mCurrentSession, new Request.GraphUserCallback() {

                // callback after Graph API response with user object
                @Override
                public void onCompleted(GraphUser user, Response response) {
                    Log.w("myConsultant", user.getId() + " " + user.getName() + " " + user.getInnerJSONObject());
                }
            });
        }
    }

但每次我得到session.isOpen（）= false。我怎么解决这个问题请帮帮我。我坚持这个。