集成环信后，APP在后台时间长了之后回来，偶尔会发不出消息，好像提示socket错误，而且也收不到了消息。

好像连接环信服务器不稳定？还是其他问题？  环信又没有手动连接服务器的api？

报错的log
11-12 13:46:53.320 25741-27911/cn.haishangxian.anshang W/System.err: java.lang.IllegalStateException: Not connected to server.
11-12 13:46:53.320 25741-27911/cn.haishangxian.anshang W/System.err:     at org.jivesoftware.smack.XMPPConnection.sendPacket(Unknown Source)
11-12 13:46:53.330 25741-27911/cn.haishangxian.anshang W/System.err:     at org.jivesoftware.smack.ChatManager.sendMessage(Unknown Source)
11-12 13:46:53.330 25741-27911/cn.haishangxian.anshang W/System.err:     at org.jivesoftware.smack.Chat.sendMessage(Unknown Source)
11-12 13:46:53.330 25741-27911/cn.haishangxian.anshang W/System.err:     at com.easemob.chat.EMSendMessageRunnable.sendMessageXmpp(Unknown Source)
11-12 13:46:53.330 25741-27911/cn.haishangxian.anshang W/System.err:     at com.easemob.chat.EMSendMessageRunnable.run(Unknown Source)
11-12 13:46:53.330 25741-27911/cn.haishangxian.anshang W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
11-12 13:46:53.330 25741-27911/cn.haishangxian.anshang W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
11-12 13:46:53.330 25741-27911/cn.haishangxian.anshang W/System.err:     at java.lang.Thread.run(Thread.java:856)