package com.sunjs.kit;
 
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
/**
 * IPv4地址和int数字的互换
 * @author sun
 */
public class IpKit {
 
  /**
   * IPv4地址转换为int类型数字
   * @param ipv4Addr
   * @return
   */
  public static int ipToInt(String ipv4Addr) {
    // 判断是否是ip格式的
    if (!isIPv4Address(ipv4Addr))
      throw new RuntimeException("Invalid ip address");
 
    // 匹配数字
    Pattern pattern = Pattern.compile("\\d+");
    Matcher matcher = pattern.matcher(ipv4Addr);
    int result = 0;
    int counter = 0;
    while (matcher.find()) {
      int value = Integer.parseInt(matcher.group());
      result = (value << 8 * (3 - counter++)) | result;
    }
    return result;
  }
 
  /**
   * 判断是否为ipv4地址
   * @param ipv4Addr
   * @return
   */
  private static boolean isIPv4Address(String ipv4Addr) {
    String lower = "(\\d|[1-9]\\d|1\\d{2}|2[0-4]\\d|25[0-5])"; // 0-255的数字
    String regex = lower + "(\\." + lower + "){3}";
    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(ipv4Addr);
    return matcher.matches();
  }
   
  /**
   * 将int数字转换成ipv4地址
   * @param ip
   * @return
   */
  public static String intToIp(int ip) {
    StringBuilder sb = new StringBuilder();
    int num = 0;
    boolean needPoint = false; // 是否需要加入'.'
    for (int i = 0; i < 4; i++) {
      if (needPoint) {
        sb.append('.');
      }
      needPoint = true;
      int offset = 8 * (3 - i);
      num = (ip >> offset) & 0xff;
      sb.append(num);
    }
    return sb.toString();
  }
   
  public static void main(String[] args) {
    String ip = "124.202.200.166";
  System.out.println(ipToInt(ip));
  System.out.println(intToIp(2093664422));
  }
   
}