问题描述：
#报错语句：
FileSystem fs = FileSystem.get(new URI("hdfs://hadoop000:8020"),new Configuration(),"hadoop");

#异常信息
Exception in thread "main" java.net.ConnectException:
Call From DESKTOP-09ASUHR/192.168.56.1 to 192.168.137.101:8020
failed on connection exception:
java.net.ConnectException:
Connection refused:
no further information;
For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
原因分析：
/root/app/hadoop-2.6.0-cdh5.7.0/etc/hadoop/core-site.xml

fs.defaultFS 参数配置使用了域名 且域名未配置映射

解决方案：
vim /root/app/hadoop-2.6.0-cdh5.7.0/etc/hadoop/core-site.xml
#8020前使用IP地址，不要使用主机名

fs.defaultFS hdfs://192.168.154.129:8820