JAVA IP and integer conversion methods

This article illustrates how IP and integer conversions work in JAVA. Share with you for your reference. Specific analysis is as follows:

One, basic knowledge

IP - > Integer:
Converts IP addresses into byte arrays
By left shift (< <) , and (&), or (|) are converted to int
Integer - > IP:
Shift the integer value to the right (> > >) , right move 24 bits, and then with the operator (&) 0xFF, the number is the first segment IP.
Shift the integer value to the right (> > >) , right 16 bits, and then with the operator (&) 0xFF, the number is the second IP segment.
Shift the integer value to the right (> > >) , 8 bits to the right, and then with the operator (&) 0xFF, the number is the third segment IP.
When the integer value is compared to the operator (&) 0xFF, the resulting number is the fourth segment IP.

Ii. Java code samples (ipv4util.java)

package michael.utils; 
import java.net.InetAddress; 
public class IPv4Util { 
 private final static int INADDRSZ = 4; 
 public static byte[] ipToBytesByInet(String ipAddr) { 
  try { 
   return InetAddress.getByName(ipAddr).getAddress(); 
  } catch (Exception e) { 
   throw new IllegalArgumentException(ipAddr + " is invalid IP"); 
  } 
 }JTA practice :Spring+ATOMIKOS 
 public static byte[] ipToBytesByReg(String ipAddr) { 
  byte[] ret = new byte[4]; 
  try { 
   String[] ipArr = ipAddr.split("\."); 
   ret[0] = (byte) (Integer.parseInt(ipArr[0]) & 0xFF); 
   ret[1] = (byte) (Integer.parseInt(ipArr[1]) & 0xFF); 
   ret[2] = (byte) (Integer.parseInt(ipArr[2]) & 0xFF); 
   ret[3] = (byte) (Integer.parseInt(ipArr[3]) & 0xFF); 
   return ret; 
  } catch (Exception e) { 
   throw new IllegalArgumentException(ipAddr + " is invalid IP"); 
  } 
 } 
 public static String bytesToIp(byte[] bytes) { 
  return new StringBuffer().append(bytes[0] & 0xFF).append('.').append( 
    bytes[1] & 0xFF).append('.').append(bytes[2] & 0xFF) 
    .append('.').append(bytes[3] & 0xFF).toString(); 
 } 
 public static int bytesToInt(byte[] bytes) { 
  int addr = bytes[3] & 0xFF; 
  addr |= ((bytes[2] << 8) & 0xFF00); 
  addr |= ((bytes[1] << 16) & 0xFF0000); 
  addr |= ((bytes[0] << 24) & 0xFF000000); 
  return addr; 
 } 
 public static int ipToInt(String ipAddr) { 
  try { 
   return bytesToInt(ipToBytesByInet(ipAddr)); 
  } catch (Exception e) { 
   throw new IllegalArgumentException(ipAddr + " is invalid IP"); 
  } 
 } 
 public static byte[] intToBytes(int ipInt) { 
  byte[] ipAddr = new byte[INADDRSZ]; 
  ipAddr[0] = (byte) ((ipInt >>> 24) & 0xFF); 
  ipAddr[1] = (byte) ((ipInt >>> 16) & 0xFF); 
  ipAddr[2] = (byte) ((ipInt >>> 8) & 0xFF); 
  ipAddr[3] = (byte) (ipInt & 0xFF); 
  return ipAddr; 
 } 
 public static String intToIp(int ipInt) { 
  return new StringBuilder().append(((ipInt >> 24) & 0xff)).append('.') 
    .append((ipInt >> 16) & 0xff).append('.').append( 
      (ipInt >> 8) & 0xff).append('.').append((ipInt & 0xff)) 
    .toString(); 
 } 
 public static int[] getIPIntScope(String ipAndMask) { 
  String[] ipArr = ipAndMask.split("/"); 
  if (ipArr.length != 2) { 
   throw new IllegalArgumentException("invalid ipAndMask with: " 
     + ipAndMask); 
  } 
  int netMask = Integer.valueOf(ipArr[1].trim()); 
  if (netMask < 0 || netMask > 31) { 
   throw new IllegalArgumentException("invalid ipAndMask with: " 
     + ipAndMask); 
  } 
  int ipInt = IPv4Util.ipToInt(ipArr[0]); 
  int netIP = ipInt & (0xFFFFFFFF << (32 - netMask)); 
  int hostScope = (0xFFFFFFFF >>> netMask); 
  return new int[] { netIP, netIP + hostScope }; 
 } 
 public static String[] getIPAddrScope(String ipAndMask) { 
  int[] ipIntArr = IPv4Util.getIPIntScope(ipAndMask); 
  return new String[] { IPv4Util.intToIp(ipIntArr[0]), 
    IPv4Util.intToIp(ipIntArr[0]) }; 
 } 
 public static int[] getIPIntScope(String ipAddr, String mask) { 
  int ipInt; 
  int netMaskInt = 0, ipcount = 0; 
  try { 
   ipInt = IPv4Util.ipToInt(ipAddr); 
   if (null == mask || "".equals(mask)) { 
    return new int[] { ipInt, ipInt }; 
   } 
   netMaskInt = IPv4Util.ipToInt(mask); 
   ipcount = IPv4Util.ipToInt("255.255.255.255") - netMaskInt; 
   int netIP = ipInt & netMaskInt; 
   int hostScope = netIP + ipcount; 
   return new int[] { netIP, hostScope }; 
  } catch (Exception e) { 
   throw new IllegalArgumentException("invalid ip scope express ip:" 
     + ipAddr + " mask:" + mask); 
  } 
 } 
 public static String[] getIPStrScope(String ipAddr, String mask) { 
  int[] ipIntArr = IPv4Util.getIPIntScope(ipAddr, mask); 
  return new String[] { IPv4Util.intToIp(ipIntArr[0]), 
    IPv4Util.intToIp(ipIntArr[0]) }; 
 } 
 public static void main(String[] args) throws Exception { 
  String ipAddr = "192.168.8.1"; 
  byte[] bytearr = IPv4Util.ipToBytesByInet(ipAddr); 
  StringBuffer byteStr = new StringBuffer(); 
  for (byte b : bytearr) { 
   if (byteStr.length() == 0) { 
    byteStr.append(b); 
   } else { 
    byteStr.append("," + b); 
   } 
  } 
  System.out.println("IP: " + ipAddr + " ByInet --> byte[]: [ " + byteStr 
    + " ]"); 
  bytearr = IPv4Util.ipToBytesByReg(ipAddr); 
  byteStr = new StringBuffer(); 
  for (byte b : bytearr) { 
   if (byteStr.length() == 0) { 
    byteStr.append(b); 
   } else { 
    byteStr.append("," + b); 
   } 
  } 
  System.out.println("IP: " + ipAddr + " ByReg --> byte[]: [ " + byteStr 
    + " ]"); 
  System.out.println("byte[]: " + byteStr + " --> IP: " 
    + IPv4Util.bytesToIp(bytearr)); 
  int ipInt = IPv4Util.ipToInt(ipAddr); 
  System.out.println("IP: " + ipAddr + " --> int: " + ipInt); 
  System.out.println("int: " + ipInt + " --> IP: " 
    + IPv4Util.intToIp(ipInt)); 
  String ipAndMask = "192.168.1.1/24"; 
  int[] ipscope = IPv4Util.getIPIntScope(ipAndMask); 
  System.out.println(ipAndMask + " --> int Address: [ " + ipscope[0] + "," 
    + ipscope[1] + " ]"); 
  System.out.println(ipAndMask + " --> IP  Address: [ " 
    + IPv4Util.intToIp(ipscope[0]) + "," 
    + IPv4Util.intToIp(ipscope[1]) + " ]"); 
  String ipAddr1 = "192.168.1.1", ipMask1 = "255.255.255.0"; 
  int[] ipscope1 = IPv4Util.getIPIntScope(ipAddr1, ipMask1); 
  System.out.println(ipAddr1 + " , " + ipMask1 + " --> int addresses   : [ " 
    + ipscope1[0] + "," + ipscope1[1] + " ]"); 
  System.out.println(ipAddr1 + " , " + ipMask1 + " --> IP addresses   : [ " 
    + IPv4Util.intToIp(ipscope1[0]) + "," 
    + IPv4Util.intToIp(ipscope1[1]) + " ]"); 
 } 
}

I hope this article has been helpful to your Java programming.