ClientCnxn: Session 0x0 for server null, unexpected error 异常解决

     ClientCnxn: Session 0x0 for server null, unexpected error 异常是由于zookeeper配置不成功引起的。

     解决方法：

     1. 确保zookeer集群安装成功。通过jps能够正确显示zookeeper管理进程QuorumPeerMain，具体安装步骤，请参考我的blogzookeeper集群安装。

     2. HBase 中的zookeeper配置正确，zookeeper实例应该是奇数个.

        <property>
                <name>hbase.zookeeper.property.clientPort</name>
                <value>2222</value>
                <description>Property from ZooKeeper's config zoo.cfg.
                The port at which the clients will connect.
                </description>
        </property>

        <property>
                <name>hbase.zookeeper.quorum</name>
                <value>machine-0,machine-1,machine-2</value>
                <description>Comma separated list of servers in the ZooKeeper Quorum.
                                                         For example,
                                                         "host1.mydomain.com,host2.mydomain.com".
                                                         By default this is set to localhost for local and

                                                         pseudo-distributed modes of operation. For a
                                                         fully-distributed setup, this should be set to a 
full
                                                         list of ZooKeeper quorum servers. If
                                                         HBASE_MANAGES_ZK is set in hbase-env.sh
                                                         this is the list of servers which we will start/s
top
                                                         ZooKeeper on.
                </description>
        </property>