import java.net.*; 
import java.io.*; 
public class usePortScanner{
public static void main(String[] args) {  
String host = "localhost";
if (args.length > 0) {
host = args[0]; 
}
// 掃描端口
for (int i = 1; i < 1024; i++){
try {
Socket s = new Socket(host, i); 
System.out.println("There is a server on port " + i + " of " + host); 
}
catch (UnknownHostException e){
System.err.println(e); 
break; 
}
catch (IOException e) 	{ // 一定不能是一個(gè)在這個(gè)端口上的server
}
} 
}
}