check which linux process the port is opened by

My linux has many ports opened by different java processes, most of them are hadoop services.

How can I know which process the port is opened by? I just use the shell script below.

 #!/bin/bash
 port=$1
 if [ -z "$port" ];then
   echo "usage: $0 port" >&2
   exit 1
 fi
 ps=$(lsof -i :"$port" |awk '/LISTEN/ {print $2}')
 if [ -z "$ps" ];then
   echo "no this port, or I don't have privilege to list the port" >&2
   exit 1
 fi
 ps -efw |grep "$ps" |grep -v grep
 exit 0
 

And the sample usage:

 $ lsport.sh 9000
 xxx       1295     1  0 Mar09 ?        01:11:35 /usr/bin/java -Dproc_namenode ...