启动tomcat失败--UnknownHostException: localhost: localhost
02.java.net.UnknownHostException: localhost: localhost
03. at java.net.InetAddress.getAllByName0(InetAddress.java:1128 )
04. at java.net.InetAddress.getAllByName0(InetAddress.java:1098 )
05. at java.net.InetAddress.getAllByName(InetAddress.java:1061 )
06. at java.net.InetAddress.getByName(InetAddress.java:958 )
07. at org.apache.catalina.core.StandardServer.await(StandardServer.java:373 )
08. at org.apache.catalina.startup.Catalina.await(Catalina.java:642 )
09. at org.apache.catalina.startup.Catalina.start(Catalina.java:602 )
10. at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
11. at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39 )
12. at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25 )
13. at java.lang.reflect.Method.invoke(Method.java:585 )
14. at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288 )
15. at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413 )

测试：
ping 127.0.0.1 可以ping通
ping localhost 不通

解决：
修改etc/hosts 文件
[oracle@bogon ~]$ su - root
Password:
[root@bogon ~]# cd ..
[root@bogon /]# cd ..
[root@bogon /]# cd etc
[root@bogon etc]# cat hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 bogon.localdomain bogon

在hosts文件中追加下面一行就OK了：
127.0.0.1 localhost.localdomain localhost