AVUser.logInInBackground(current.getUsername(), "password", new LogInCallback<AVUser>() {
                @Override
                public void done(AVUser avUser, AVException e) {
                    AVQuery<AVUser> followerQuery = null;
                    try {
                        followerQuery = avUser.followerQuery(AVUser.class);
                        followerQuery.setLimit(1);
                        followerQuery.findInBackground(new FindCallback<AVUser>() {
                            @Override
                            public void done(List<AVUser> parseObjects, AVException parseException) {
                                // parseObjects包含了userA的粉丝列表

                            }
                        });
                    } catch (Exception e1) {
                        e1.printStackTrace();
                    }
                }
            });

这个查询为什么报错

com.avos.avoscloud.AVException: No valid session token, make sure signUp or login has been called.

这不是刚登陆完成么？