情况是这样的：
[myid=1]/0:0:0:0:0:0:0:0:2181:QuorumCnxManager@382] - Cannot open channel to 1 at election address os1.example.com/192.168.0.110:3888
java.net.ConnectException: 拒绝连接
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:579)
at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:368)
at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectAll(QuorumCnxManager.java:402)
at org.apache.zookeeper.server.quorum.FastLeaderElection.lookForLeader(FastLeaderElection.java:840)
at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:762)
2016-7-7 23:36:35,666 [myid:3] - INFO [QuorumPeer[myid=3]/0:0:0:0:0:0:0:0:2181:FastLeaderElection@849] - Notification time out: 60000
我的环境是VM下3个centos7虚拟机桥接网络，zookeeper三个都启动了还算拒绝连接
hosts与hostname都配置好了，并且可以相互ping通
确定防火墙已经关闭
关闭的命令：
systemctl status firewalld.service #检查防火墙状态
systemctl stop firewalld.service #关闭防火墙
systemctl disable firewalld.service #禁止开机启动防火墙
关闭SELINUX
vim /etc/selinux/config
#SELINUX=enforcing #注释掉
#SELINUXTYPE=targeted #注释掉
SELINUX=disabled #增加
三台机器在这种情况下，还是互相拒绝连接，后来通过百度，终于找到如下的链接（原谅我吧，大部分的内容都是照它写的，不过情况确实是一样的）
http://www.oschina.net/question/914277_2139350?fromerr=U9hFdhpN
这个发帖的人询问了大神以后，通过如下的办法解决了问题：
将所有机器的/etc/hosts中的127.0.1.1这一行去掉
我照着试了下，果然有效！！！