预处理启动遇到问题：找不到类

Caused by: java.lang.RuntimeException: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class org.apache.hadoop.hdfs.server.namenode.ha.AdaptiveFailoverProxyProvider not found

解决办法：将hdfs-site.xml里的Class org.apache.hadoop.hdfs.server.namenode.ha.AdaptiveFailoverProxyProvider替换为org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider