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.