安装完成zookeeper后，用Java代码连接阿里云上zookeeper，报出如下错误
2018-04-09 14:11:56,122 [myid:1] - INFO [solang/*.*.*.*:3887:QuorumCnxManager$Listener@739] - My election bind port: solang/*.*.*.*:3887
2018-04-09 14:11:56,123 [myid:1] - ERROR [solang/*.*.*.*:3887:QuorumCnxManager$Listener@763] - Exception while listening
java.net.BindException: Cannot assign requested address (Bind failed)
at java.net.PlainSocketImpl.socketBind(Native Method)
at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:387)
at java.net.ServerSocket.bind(ServerSocket.java:375)
at java.net.ServerSocket.bind(ServerSocket.java:329)
at org.apache.zookeeper.server.quorum.QuorumCnxManager$Listener.run(QuorumCnxManager.java:742)
2018-04-09 14:11:57,123 [myid:1] - INFO [solang/*.*.*.*:3887:QuorumCnxManager$Listener@776] - Leaving listener
2018-04-09 14:11:57,124 [myid:1] - ERROR [solang/*.*.*.*:3887:QuorumCnxManager$Listener@778] - As I'm leaving the listener thread, I won't be able to participate in leader election any longer: solang/*.*.*.*:3887
2018-04-09 14:11:59,140 [myid:1] - WARN [WorkerSender[myid=1]:QuorumCnxManager@588] - Cannot open channel to 2 at election address solang/*.*.*.*:3888
java.net.SocketTimeoutException: connect timed out
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:562)
at org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:538)
at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:452)
at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:433)
at java.lang.Thread.run(Thread.java:748)
参考了很多博客才解决，现在把可能的原因做一下记录
一、主机与服务器的映射
1.修改本地 C:\Windows\System32\drivers\etc\hosts文件
在下面添加一条“ 阿里云的外网ip 主机名 ” 字段
2.修改阿里云服务器上的 /etc/hosts文件的外网IP地址修改为内网IP地址
3.重启zookeeper，再尝试连接
二、阿里云服务器端口未开放
1.进入阿里云ECS实例控制台
2.选择更多-安全组配置
3.选择配置规则
4.选择添加安全组规则
5.添加安全组规则
可根据需要选择协议类型及设置对应端口范围，为了省事，我选择协议类型为全部。点击确定，安全组规则设置完成。
三、修改zookeeper配置参数
在每一个zookeeper节点下的zoo.cfg配置文件中加入参数quorumListenOnAllIPs=true
然后再重启zookeeper集群，就可以正常连接了
quorumListenOnAllIPs：默认为false，如果设为true，zk服务器会监听所有可达IP上的连接。
在本地虚拟机部署时，不需要设置就可以连接，但是在阿里云上部署就不行了。找了好久才发现这个原因。目前还不是太懂这个的原理，反正外网连接设置上就对了
