JAVA代码根据IP/掩码位数格式地址段得到起始地址和结束地址,可用IP数量,掩码

网上根据IP/掩码位数获取起始地址的方法大多是JS代码实现.项目需要在后台进行处理.提供一份根据IP/掩码获取起始地址通过java代码实现

//IP  String ip = "192.168.3.0";  //掩码位数  String mask = "24";

1.根据掩码位数获取掩码

/**  * 根据掩码位数获取掩码  */  private static String getNetMask(String mask) {      int inetMask =Integer.parseInt(mask);      if(inetMask > 32){          return null;      }      //子网掩码为1占了几个字节      int num1 = inetMask/8;      //子网掩码的补位位数      int num2 = inetMask%8;      int array[] = new int[4];      for (int i = 0; i < num1; i++) {          array[i] = 255;      }      for (int i = num1; i < 4; i++) {          array[i] = 0;      }      for (int i = 0; i < num2; num2--) {          array[num1] += Math.pow(2, 8-num2);      }      String netMask =  array[0] + "." + array[1] + "." + array[2] + "." + array[3];      return netMask;  }  

2.根据ip地址和掩码获取起始IP

private String getLowAddr(String ipinfo, String netMask) {      String lowAddr = "";      int ipArray[] = new int[4];      int netMaskArray[] = new int[4];      if(4 != ipinfo.split("\\.").length || "" == netMask){          return null;      }      for (int i = 0; i < 4; i++) {          try{              ipArray[i] = Integer.parseInt(ipinfo.split("\\.")[i]);          }catch(NumberFormatException e){              String ip = ipinfo.replaceAll("\n", "");              ipArray[i] = Integer.parseInt(ip.split("\\.")[i]);          }          netMaskArray[i] = Integer.parseInt(netMask.split("\\.")[i]);          if(ipArray[i] > 255 || ipArray[i] < 0 || netMaskArray[i] > 255 || netMaskArray[i] < 0){                      return null;          }          ipArray[i] = ipArray[i]&netMaskArray[i];      }      //构造最小地址      for (int i = 0; i < 4; i++){          if(i == 3){              ipArray[i] = ipArray[i] + 1;          }          if ("" == lowAddr){              lowAddr +=ipArray[i];          } else{              lowAddr += "." + ipArray[i];          }      }      return lowAddr;  }  

3.根据ip地址和掩码获取终止IP

private String getHighAddr(String ipinfo, String netMask) {      String lowAddr = getLowAddr(ipinfo, netMask);      int hostNumber = getHostNumber(netMask);      if("" == lowAddr || hostNumber == 0){          return null;      }      int lowAddrArray[] = new int[4];      for (int i = 0; i < 4; i++) {          lowAddrArray[i] = Integer.parseInt(lowAddr.split("\\.")[i]);          if(i == 3){              lowAddrArray[i] = lowAddrArray[i] - 1;          }      }      lowAddrArray[3] = lowAddrArray[3] + (hostNumber - 1);      if(lowAddrArray[3] >255){          int k = lowAddrArray[3] / 256;          lowAddrArray[3] = lowAddrArray[3] % 256;          lowAddrArray[2] = lowAddrArray[2] + k;      }      if(lowAddrArray[2] > 255){          int  j = lowAddrArray[2] / 256;             lowAddrArray[2] = lowAddrArray[2] % 256;             lowAddrArray[1] = lowAddrArray[1] + j;             if(lowAddrArray[1] > 255){                 int  k = lowAddrArray[1] / 256;                 lowAddrArray[1] = lowAddrArray[1] % 256;                 lowAddrArray[0] = lowAddrArray[0] + k;             }         }      String highAddr = "";      for(int i = 0; i < 4; i++){          if(i == 3){              lowAddrArray[i] = lowAddrArray[i] - 1;          }          if("" == highAddr){              highAddr = lowAddrArray[i]+"";          }else{              highAddr += "." + lowAddrArray[i];          }      }      return highAddr;  }  

4.ip转换Long

private long ip2long(String ip) {      String[] ips = ip.split("[.]");      long num = 16777216L * Long.parseLong(ips[0]) + 65536L              * Long.parseLong(ips[1]) + 256 * Long.parseLong(ips[2])              + Long.parseLong(ips[3]);      return num;  }  

5.实际可用ip数量

private int getHostNumber(String netMask) {      int hostNumber = 0;      int netMaskArray[] = new int[4];      for (int i = 0; i < 4 ; i++) {          netMaskArray[i] = Integer.parseInt(netMask.split("\\.")[i]);          if(netMaskArray[i] < 255){              hostNumber =  (int) (Math.pow(256,3-i) * (256 - netMaskArray[i]));              break;          }      }      return hostNumber;  }  

注意:通过上面获取到的开始和结束IP是第一个可用最后一个可用IP,以掩码位数为24位的为例.一个网段0一般为网络地址,255一般为广播地址.

另外:获取的可用IP数量为256是包含网络地址和广播地址的.这一点一定要清楚.