android - FB Android-SDK : How to wait until callback of request is completed

Question

我试图等到 Request 的回调函数的 onCompleted() 完成。然而，RequestAsyncTask 的方法get() 总是在这种情况之前返回。因此，在我的程序的进一步陈述中会出现问题。 println输出总是在数据库查询后显示，不等于null。这是我的代码:

private void onSessionStateChange(Session session, SessionState state, Exception exception) {
        if (state.isOpened()) {
            // show authendicated ui
            Log.i(TAG, "Logged in...");
            try {
                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) {
                            MyApplication.userId = user.getId();
                            System.out.println("User id: " + MyApplication.userId);
                        }

                    }
                }).executeAsync().get();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (ExecutionException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            boolean isNewUser = !MyApplication.dbConnection.isUidRegistered(MyApplication.userId);

这会导致我的数据库查找 null 作为 uid。我该如何解决这个问题？

Answer 1

你应该把这部分代码放在:

boolean isNewUser = !MyApplication.dbConnection.isUidRegistered(MyApplication.userId);

在你的请求回调中:

 @Override
public void onCompleted(GraphUser user, Response response) {
    if (user != null) {
        MyApplication.userId = user.getId();
        System.out.println("User id: " + MyApplication.userId);

        boolean isNewUser = !MyApplication.dbConnection.isUidRegistered(MyApplication.userId);
        // here you should continue your work
    }    
}