关于IP的工具类

很多WEB应用有用到对IP的处理，最近刚好在做这个东西，顺便记录一下：

import org.apache.commons.lang.StringUtils;

/**
 * Ip工具类
 *
 */
public class IpUtils {

    /**
     * 将IP地址格式化为定长的IP段.
     * 例如: 192.168.0.122 => 192.168.000.122
     * @param ip
     * @return
     */
    public static String formatIp(String ip) {
        String[] ips = ip.split("\.");
        String newIp = "";
        for (int i = 0; i < ips.length; i++) {
            switch (ips[i].length()) {
            case 1:
                newIp += "00" + ips[i] + ".";
                break;
            case 2:
                newIp += "0" + ips[i] + ".";
                break;
            case 3:
                newIp += ips[i] + ".";
                break;
            }
        }
        newIp = newIp.substring(0, newIp.length() - 1);
        return newIp;
    }

    /**
     * 将定长的IP段还原.
     * 例如: 010.001.000.122 => 10.1.0.122
     * @param ip
     * @return
     */
    public static String normalIp(String ip) {
        //转换ip字符串格式
        String[] ipArray = StringUtils.split(ip, ".");
        for(int i=0;i<ipArray.length;i++)
        {
            int temp = Integer.parseInt(ipArray[i]);
            ipArray[i] = String.valueOf(temp);
        }
        return StringUtils.join(ipArray,".");
    }
    
    /**
     * 把ip地址转换成数字
     * @param ip
     * @return
     */
    public static long ip2Long(String ip) {
        String[] ipArray = StringUtils.split(ip, ".");
        long retLong = 0;
        if (!checkIP(ip)) {
            return -1;
        }
        for(int i=0;i<ipArray.length;i++)
        {
            long temp = Long.parseLong(ipArray[i]);
            int j = 3 - i;
            while (j > 0) {
                temp = temp * 256;
                j--;
            }
            retLong += temp;
        }
        return retLong;
    }
    
    public static boolean checkIP(String ip){
        return ip.matches("\d{1,3}+\.\d{1,3}+\.\d{1,3}+\.\d{1,3}");
    }

    
    public static void main(String[] args) {
        System.out.println(IpUtils.ip2Long("255.255.255.255"));
        System.out.println(IpUtils.checkIP("19a2.1685.0.4"));
    }

}