java判断是否是ip的方法

java可以使用正则表达式判断是否是IP。（推荐：java视频教程）

实现代码如下：

  
package com.you.dao;  
 
import java.util.regex.Matcher;  
import java.util.regex.Pattern;  
 
  
public class IpAddress   
{  
    public static class IpAdd  
    {  
        public boolean isIP(String addr)  
        {  
            if(addr.length() < 7 || addr.length() > 15 || "".equals(addr))  
            {  
                return false;  
            }  
              
            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;  
        }  
    }  
 
      
    public static void main(String[] args)   
    {  
          
         String oneAddress = "10.127.30.45";  
           
         String twoAddress = "127.30.45";  
           
         String threeAddress = "7.0.4";  
           
         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));  
    }  
 
}

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