Java – Convert IP address to Decimal Number
In this tutorial, we show you how to convert an IP address to its decimal equivalent in Java, and vice versa. For examples :
255.255.255.255 <-> 4294967295
192.168.1.2 <-> 3232235778
1. IP Address to Decimal
We show you two ways to convert an IP address to a decimal number
- Normal power of 256
- Bit shifting
1.1 First Example – Power of 256
The IP address is “base 256”, to convert 192.168.1.2 to decimal (base 10) the formula is:
192 x (256)^3 + 168 x (256)^2 + 1 x (256)^1 + 2 (256)^0 = ?
3221225472 + 11010048 + 256 + 2 = 3232235778
public long ipToLong(String ipAddress) {
String[] ipAddressInArray = ipAddress.split("\\.");
long result = 0;
for (int i = 0; i < ipAddressInArray.length; i++) {
int power = 3 - i;
int ip = Integer.parseInt(ipAddressInArray[i]);
result += ip * Math.pow(256, power);
}
return result;
}
Some developers prefer to use modular like this
result += (Integer.parseInt(ipAddressInArray[i]) % 256 * Math.pow(256, power));
1.2 Second Example - Bit shifting
Review the binary bit shifting graph below :
public long ipToLong(String ipAddress) {
long result = 0;
String[] ipAddressInArray = ipAddress.split("\\.");
for (int i = 3; i >= 0; i--) {
long ip = Long.parseLong(ipAddressInArray[3 - i]);
//left shifting 24,16,8,0 and bitwise OR
//1. 192 << 24
//1. 168 << 16
//1. 1 << 8
//1. 2 << 0
result |= ip << (i * 8);
}
return result;
}
192 00000000 00000000 00000000 11000000
-----------------------------------------------
192 << 24 11000000 00000000 00000000 00000000
Result 00000000 00000000 00000000 00000000
Result |= 11000000 00000000 00000000 00000000
168 00000000 00000000 00000000 10101000
-----------------------------------------------
168 << 16 00000000 10101000 00000000 00000000
Result 11000000 00000000 00000000 00000000
Result |= 11000000 10101000 00000000 00000000
1 00000000 00000000 00000000 00000001
-----------------------------------------------
1 << 8 00000000 00000000 00000001 00000000
Result 11000000 10101000 00000000 00000000
Result |= 11000000 10101000 00000001 00000000
2 00000000 00000000 00000000 00000010
-----------------------------------------------
2 << 0 00000000 00000000 00000000 00000010
Result 11000000 10101000 00000001 00000000
Result |= 11000000 10101000 00000001 00000010
Convert the final binary code to decimal, by hand calculation :) ~
Result 11000000 10101000 00000001 00000010
index 0 - 31, start from right.
31(1),30(1),29,28,27,26,25,24,23(1),22,21(1),20,19(1),18,17,16,15,14,13,12,11,10,9,8(1),7,6,5,4,3,2,1(1),0
Decimal 1x2^31 + 1x2^30 + 1x2^23 + 1x2^21 + 1x2^19 + 1x2^8 + 1x2^1
2147483648 + 1073741824 + 8388608 + 2097152 + 524288 + 256 + 2
3232235778
2. Decimal to IP Address
We show you two bit shifting and "0xff" masking examples to convert a decimal number back to IP address. The bit shifting is very hard to explain in words, it's better review the binary flows below :
2.1 First Example.
//ip = 3232235778
public String longToIp(long ip) {
StringBuilder result = new StringBuilder(15);
for (int i = 0; i < 4; i++) {
result.insert(0,Long.toString(ip & 0xff));
if (i < 3) {
sb.insert(0,'.');
}
ip = ip >> 8;
}
return result.toString();
}
Review the bit shifting flows :
3232235778 11000000 10101000 00000001 00000010
<<Loop 1>>
-----------------------------------------------------------
ip 11000000 10101000 00000001 00000010
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 00000010 = 2
Result Append .2
-------------------------> 8
ip >> 8 00000000 11000000 10101000 00000001 {off 00000010}
<<Loop 2>>
-----------------------------------------------------------
ip 00000000 11000000 10101000 00000001
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 00000001 = 1
Result Append 1.2
----------------> 8
ip >> 8 00000000 00000000 11000000 10101000 {off 00000001}
<<Loop 3>>
-----------------------------------------------------------
ip 00000000 00000000 11000000 10101000
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 10101000 = 168
Result Append 168.1.2
-------> 8
ip >> 8 00000000 00000000 00000000 11000000 {off 10101000}
<<Loop 4>>
-----------------------------------------------------------
ip 00000000 00000000 00000000 11000000
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 11000000 = 192
Result Append 192.168.1.2
-----------> 8
ip >> 8 00000000 00000000 00000000 00000000 {off 11000000}
2.2 Second Example.
//ip = 3232235778
public String longToIp(long ip) {
return ((ip >> 24) & 0xFF) + "."
+ ((ip >> 16) & 0xFF) + "."
+ ((ip >> 8) & 0xFF) + "."
+ (ip & 0xFF);
}
3232235778 11000000 10101000 00000001 00000010
1. (ip >> 24) & 0xFF
-----------------------------------------------------------
ip 11000000 10101000 00000001 00000010
-------------------------------------> 24
ip >> 24 00000000 00000000 00000000 11000000 {off 10101000 00000001 00000010}
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 11000000 = 192
2. (ip >> 16) & 0xFF
-----------------------------------------------------------
ip 11000000 10101000 00000001 00000010
-------------------------------------> 16
ip >> 16 00000000 00000000 11000000 10101000 {off 00000001 00000010}
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 10101000 = 168
3. (ip >> 8) & 0xFF
-----------------------------------------------------------
ip 11000000 10101000 00000001 00000010
--------------------------------------> 8
ip >> 24 00000000 11000000 10101000 00000001 {off 00000010}
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 00000001 = 1
4. ip & 0xFF
-----------------------------------------------------------
ip 11000000 10101000 00000001 00000010
& 0xff 00000000 00000000 00000000 11111111
Result 00000000 00000000 00000000 00000010 = 2
3. Java Source Code
Full Java example to demonstrate above scenario :
package com.mkyong.core;
public class JavaBitwiseExample {
public static void main(String[] args) {
JavaBitwiseExample obj = new JavaBitwiseExample();
System.out.println("iptoLong : " + obj.ipToLong("192.168.1.2"));
System.out.println("iptoLong2 : " + obj.ipToLong2("192.168.1.2"));
System.out.println("longToIp : " + obj.longToIp(3232235778L));
System.out.println("longToIp2 : " + obj.longToIp2(3232235778L));
}
// example : 192.168.1.2
public long ipToLong(String ipAddress) {
// ipAddressInArray[0] = 192
String[] ipAddressInArray = ipAddress.split("\\.");
long result = 0;
for (int i = 0; i < ipAddressInArray.length; i++) {
int power = 3 - i;
int ip = Integer.parseInt(ipAddressInArray[i]);
// 1. 192 * 256^3
// 2. 168 * 256^2
// 3. 1 * 256^1
// 4. 2 * 256^0
result += ip * Math.pow(256, power);
}
return result;
}
public long ipToLong2(String ipAddress) {
long result = 0;
String[] ipAddressInArray = ipAddress.split("\\.");
for (int i = 3; i >= 0; i--) {
long ip = Long.parseLong(ipAddressInArray[3 - i]);
// left shifting 24,16,8,0 and bitwise OR
// 1. 192 << 24
// 1. 168 << 16
// 1. 1 << 8
// 1. 2 << 0
result |= ip << (i * 8);
}
return result;
}
public String longToIp(long i) {
return ((i >> 24) & 0xFF) +
"." + ((i >> 16) & 0xFF) +
"." + ((i >> 8) & 0xFF) +
"." + (i & 0xFF);
}
public String longToIp2(long ip) {
StringBuilder sb = new StringBuilder(15);
for (int i = 0; i < 4; i++) {
// 1. 2
// 2. 1
// 3. 168
// 4. 192
sb.insert(0, Long.toString(ip & 0xff));
if (i < 3) {
sb.insert(0, '.');
}
// 1. 192.168.1.2
// 2. 192.168.1
// 3. 192.168
// 4. 192
ip = ip >> 8;
}
return sb.toString();
}
/*
private static void printPrettyBinary(String binary) {
String s1 = String.format("%32s", binary).replace(' ', '0');
System.out.format("%8s %8s %8s %8s %n",
s1.substring(0, 8),
s1.substring(8, 16),
s1.substring(16, 24),
s1.substring(24, 32));
}
*/
}
Output
iptoLong : 3232235778
iptoLong2 : 3232235778
longToIp : 192.168.1.2
longToIp2 : 192.168.1.2
地址：http://www.mkyong.com/java/java-convert-ip-address-to-decimal-number/
Java – Convert IP address to Decimal Number的更多相关文章
- [转]How to convert IP address to country name
本文转自:http://www.codeproject.com/Articles/28363/How-to-convert-IP-address-to-country-name Download ...
- lwip IP address handling 关于 IP 地址的 操作 API接口
lwip 2.0.3 IP address handling /** * @file * IP address API (common IPv4 and IPv6) */ 1.u32_t ipadd ...
- Convert IPv6 Address to IP numbers (C#)
URL: http://lite.ip2location.com/ Use the code below to convert the IP address of your web visitors ...
- Java Regex match IP address
Reference: [1] https://www.mkyong.com/regular-expressions/how-to-validate-ip-address-with-regular-ex ...
- poj 2105 IP Address(水题)
一.Description Suppose you are reading byte streams from any device, representing IP addresses. Your ...
- IP Address 分类： POJ 2015-06-12 19:34 12人阅读 评论(0) 收藏
IP Address Time Limit: 1000MS Memory Limit: 30000K Total Submissions: 19125 Accepted: 11053 Desc ...
- 华东师大OJ：IP Address【IP地址转换】
/*===================================== IP Address Time Limit:1000MS Memory Limit:30000KB Total Subm ...
- poj2105 IP Address（简单题）
题目链接:id=2105">http://poj.org/problem?id=2105 ----------------------------------------------- ...
- IP address/地址 检查
1.Determine if a string is a valid IP address in C Beej's Guide to Network Programming 2.9.14. inet_ ...
随机推荐
- 设定StatusBar的文字成不同的颜色
设定StatusBar上的文字,该文字以StatusBar所在Form的字型设定为准,并以form的ForeColor为字的颜色,文字过长时,自动会截除这个程式的实质意义不太大,因为当文字被盖掉後需自 ...
- MySQL工具1：mysqladmin
每两秒显示一下MySQL的状态,一共显示5次. # mysqladmin -uroot -p -i 2 -c 5 status 查看MySQL的运行状态: #mysqladmin -uroot -p ...
- SQL Server表描述 及 字段描述的增、删、改、查询
SQL Server表描述 及 字段描述的增.删.改.查询 --测试: --创建表及描述信息 ),isname )) --为表添加描述信息 EXECUTE sp_addextendedproperty ...
- python线程详解
#线程状态 #线程同步(锁)#多线程的优势在于可以同时运行多个任务,至少感觉起来是这样,但是当线程需要共享数据时,可能存在数据不同步的问题. #threading模块#常用方法:'''threadin ...
- from会存在潜在的陷阱
# -*- coding: utf-8 -*- #python 27 #xiaodeng #from会存在潜在的陷阱 #from时,可能会遇到相同变量名,变量会被悄悄覆盖掉, #但是import语句不 ...
- ios block常见的错误（二）——循环引用
这篇博文继续block的常见错误——循环引用. 循环引用是很多初学者不能察觉的,其产生的原因,是block中的代码会对对象进行强引用. 读者请阅读示例代码1,并思考示例代码1所创建的对象能否被正常销毁 ...
- dom 解析xml文件
JAXP技术 JAXP即Java Api for Xml Processing该API主要是SUN提供的用于解析XML数据的一整套解决方案,主要包含了DOM和SAX解析技术.大家可以参见SUN的以下两 ...
- Android WebDriver 浏览器自动测试工具介绍
Selenium WebDriver 是浏览器自动测试工具,提供轻量级和优雅的方式来测试web应用.Selenium WebDriver作为Android SDK extra,支持Android 2. ...
- python学习笔记011——内置函数sum()
1 描述 sum() 方法对系列进行求和计算. 2 语法 sum(iterable[, start]) iterable:可迭代对象,如列表. start:指定相加的参数,如果没有设置这个值,默认为0 ...
- DBA_实践指南系列4_Oracle Erp R12系统备份和恢复Backup（案例）
2013-12-04 Created By BaoXinjian