java 判断字符串是否是IP

package org.cric.d;

public class WhetherIP{

 public static String trimSpaces(String IP){//去掉IP字符串前后所有的空格 
        while(IP.startsWith(" ")){ 
               IP= IP.substring(1,IP.length()).trim(); 
            } 
        while(IP.endsWith(" ")){ 
               IP= IP.substring(0,IP.length()-1).trim(); 
            } 
        return IP; 
    } 
 public static boolean isIp(String IP){//判断是否是一个IP 
        boolean b = false; 
        IP = trimSpaces(IP); 
        if(IP.matches("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}")){ 
            String s[] = IP.split("\\."); 
            if(Integer.parseInt(s[0])<255) 
                if(Integer.parseInt(s[1])<255) 
                    if(Integer.parseInt(s[2])<255) 
                        if(Integer.parseInt(s[3])<255) 
                            b = true; 
        } 
        return b; 
    } 
 /**
  * @param args
  */
 public static void main(String[] args) {
  // TODO Auto-generated method stub
  String s =" 127.0.0.1 "; 
  //String s =" 23432423 ";
        System.out.println(isIp(s)?"是一个IP":"不是一个IP");
 }

}