当我们在启动ZooKeeper时如果报错如下：
2021-04-26 17:42:37,967 [myid:3] - INFO [main:NIOServerCnxnFactory@686] - binding to port 0.0.0.0/0.0.0.0:2181
2021-04-26 17:42:37,968 [myid:3] - ERROR [main:QuorumPeerMain@101] - Unexpected exception, exiting abnormally
java.net.BindException: Address already in use
at sun.nio.ch.Net.bind0(Native Method)
at sun.nio.ch.Net.bind(Net.java:433)
at sun.nio.ch.Net.bind(Net.java:425)
at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:67)
at org.apache.zookeeper.server.NIOServerCnxnFactory.configure(NIOServerCnxnFactory.java:687)
at org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:148)
at org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:123)
at org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:82)
说明ZooKeeper中有端口被占用了，我们这里涉及到的端口是2181端口，通过如下指令查看哪个进程占用了该端口：
netstat -ano | findstr "2181"
如果没有netstat指令，可以执行如下指令安装后再去查看：
yum -y install net-tools
然后找到该进程的id，执行如下指令结束该进程即可：
kill -9 进程pid
最后再去启动ZooKeeper发现就ok了
