Java method to determine whether it is an IP

/** 
 1. @Title:IpAddress.java 
 2. @Package:com.you.dao 
 3. @Description:用正则表达式判断是否为IP 
 */  
package com.you.dao;  
 
import java.util.regex.Matcher;  
import java.util.regex.Pattern;  
 
/** 
 7. @类名:IpAddress 
 8. @描述:用正则表达式判断是否为IP 
 9. @Author：Administrator 
 10. @date: 2014年3月4日 下午10:55:06 
 */  
public class IpAddress   
{  
    public static class IpAdd  
    {  
        public boolean isIP(String addr)  
        {  
            if(addr.length() < 7 || addr.length() > 15 || "".equals(addr))  
            {  
                return false;  
            }  
            /** 
             * 判断IP格式和范围 
             */  
            String rexp = "([1-9]|[1-9]\\d|1\\d{2}|2[0-4]\\d|25[0-5])(\\.(\\d|[1-9]\\d|1\\d{2}|2[0-4]\\d|25[0-5])){3}";  
 
            Pattern pat = Pattern.compile(rexp);    
 
            Matcher mat = pat.matcher(addr);    
 
            boolean ipAddress = mat.find();  
 
            return ipAddress;  
        }  
    }  
 
    /** 
     * @Title : main 
     * @Description : IP可能的范围是0-255.0-255.0-255.0-255 
     * @param args 
     */  
    public static void main(String[] args)   
    {  
        /** 
         * 符合IP地址的范围 
         */  
         String oneAddress = "10.127.30.45";  
         /** 
         * 符合IP地址的长度范围但是不符合格式 
         */  
         String twoAddress = "127.30.45";  
         /** 
         * 不符合IP地址的长度范围 
         */  
         String threeAddress = "7.0.4";  
         /** 
         * 不符合IP地址的长度范围但是不符合IP取值范围 
         */  
         String fourAddress = "255.255.255.2567";  
 
         IpAdd ipAdd = new IpAdd();  
 
         //判断oneAddress是否是IP  
         System.out.println(ipAdd.isIP(oneAddress));  
 
         //判断twoAddress是否是IP  
         System.out.println(ipAdd.isIP(twoAddress));  
 
         //判断threeAddress是否是IP  
         System.out.println(ipAdd.isIP(threeAddress));  
 
         //判断fourAddress是否是IP  
         System.out.println(ipAdd.isIP(fourAddress));  
    }  
 
}