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");
}

}