面试官:如果要存ip地址,用什么数据类型比较好
节省空间,不管是数据存储空间,还是索引存储空间 便于使用范围查询(BETWEEN...AND),且效率更高
使用字符串和无符号整数来存储IP的具体性能分析及benchmark,可以看这篇文章。
https://bafford.com/2009/03/09/mysql-performance-benefits-of-storing-integer-ip-addresses/
不便于阅读 需要手动转换
对于转换来说,MySQL提供了相应的函数来把字符串格式的IP转换成整数INET_ATON,以及把整数格式的IP转换成字符串的INET_NTOA。如下所示:
mysql> select inet_aton('192.168.0.1');+--------------------------+| inet_aton('192.168.0.1') |+--------------------------+| 3232235521 |+--------------------------+1 row in set (0.00 sec)mysql> select inet_ntoa(3232235521);+-----------------------+| inet_ntoa(3232235521) |+-----------------------+| 192.168.0.1 |+-----------------------+1 row in set (0.00 sec)
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对于转换字符串IPv4和数值类型,可以放在应用层,下面是使用java代码来对二者转换:
package com.mikan;/*** @author Mikan* @date 2015-09-22 10:59*/public class IpLongUtils {/*** 把字符串IP转换成long** @param ipStr 字符串IP* @return IP对应的long值*/public static long ip2Long(String ipStr) {String[] ip = ipStr.split("\\.");return (Long.valueOf(ip[0]) << 24) + (Long.valueOf(ip[1]) << 16)+ (Long.valueOf(ip[2]) << 8) + Long.valueOf(ip[3]);}/*** 把IP的long值转换成字符串** @param ipLong IP的long值* @return long值对应的字符串*/public static String long2Ip(long ipLong) {StringBuilder ip = new StringBuilder();ip.append(ipLong >>> 24).append(".");ip.append((ipLong >>> 16) & 0xFF).append(".");ip.append((ipLong >>> 8) & 0xFF).append(".");ip.append(ipLong & 0xFF);return ip.toString();}public static void main(String[] args) {System.out.println(ip2Long("192.168.0.1"));System.out.println(long2Ip(3232235521L));System.out.println(ip2Long("10.0.0.1"));}}
输出结果为:
3232235521192.168.0.1167772161
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