解决方法
你应该能够这样做：
Notification notif = new Notification.Builder(context)
.setContentTitle("Title")
.setContentText("content")
.setSmallIcon(R.drawable.ic_small)
.setLargeIcon(bitmap)
.setStyle(new Notification.BigPictureStyle()
.bigPicture(bigBitmap)
.setBigContentTitle("big title"))
.build();
