java将IP地址转换为数字以及逆向转换（位运算和0xFF的使用）第二季

来源：互联网发布：淘宝hd历史版本编辑：程序博客网时间：2024/05/22 02:11

原文：

http://www.mkyong.com/java/java-convert-ip-address-to-decimal-number/

来自同一个博客。

IP转为数字（第二种算法。用左移、按位或实现。效率比上一篇的更高。）：

 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   << 0result |= ip << (i * 8); }return result;  }

数字转为IP，两种算法都差不多：

  //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) {result.insert(0,'.');} ip = ip >> 8;}return result.toString();  }  //ip = 3232235778  public String longToIp2(long ip) { return ((ip >> 24) & 0xFF) + "." + ((ip >> 16) & 0xFF) + "." + ((ip >> 8) & 0xFF) + "." + (ip & 0xFF);  }

完整代码：

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 : 192.168.1.2public long ipToLong(String ipAddress) { // ipAddressInArray[0] = 192String[] 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 * 256^0result += 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 << 0result |= 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. 192sb.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. 192ip = ip >> 8; } return sb.toString();}}

Output:

iptoLong  : 3232235778iptoLong2 : 3232235778longToIp  : 192.168.1.2longToIp2 : 192.168.1.2

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