我从Facebook得到一个这样的参数:{"object":"page","entry":[{"id":"xxxxxxxx","time":1542363897584,"messaging":[{"sender":{"id":"xxxxxxxx"},"recipient":{"id":"xxxxxxxxx"},"timestamp":1542363897166,"message":{"mid":"OBhuHFel0lF_GFyp6kyHryjVQbb61lOQl3sqOSZcLpQhcO37Lx6NSp2tKg6pdz_Zd22EQOwBqftDtH2Au40ECw","seq":142884,"text":"xxxxxxxxxxx"}}]}],"dc_action":"xxxxxxxx"}
。请告诉我从中上获取线程ID的方法。