java IP地址网段计算的示例代码

根据IP地址与字段掩码计算网段最大最小IP

package c04;
import java.net.UnknownHostException;

public class IPNetworkSegmentCalculation {
  public static void main(String[] args) throws UnknownHostException {
    String ip = "192.168.126.2";
    String mask = "255.255.255.0";
    findMask();
  }
  public static void findMask(){
    String mask = "255.255.255.0";
    String ip = "192.168.126.2";
    String[] ipArray =  ip.split("[.]");
    String[] maskArray = mask.split("[.]");

    String minIp = "";
    String maxIp = "";
    int subMask = 0;
    for(int i=0 ;i < maskArray.length ; i++){
      int maskTmp = Integer.valueOf(maskArray[i]);
      int ipTmp = Integer.valueOf(ipArray[i]);
      int mi = maskTmp&ipTmp;

      //System.out.println("==============="+maskTmp+" "+ipTmp);
      if(ipTmp == mi && maskTmp==255){
        minIp = minIp + ipTmp+"." ;
        maxIp = maxIp + ipTmp+"." ;
        subMask = subMask + 8;
      }else{
        minIp = minIp + mi+"." ;
        maxIp = maxIp + maxNetSeg(Integer.toBinaryString(maskTmp),mi)+".";
        subMask = subMask + subMaskNum(Integer.toBinaryString(maskTmp));
      }

    }

    minIp = minIp.substring(0,minIp.length()-1);
    maxIp = maxIp.substring(0,maxIp.length()-1);
    System.out.println("minip "+minIp);
    System.out.println("maxip "+maxIp);
    System.out.println("mask "+subMask);
  }
  private static int calculate(int n) {
    if (n == 0)
      return 1;
    return 2 * calculate(n - 1);
  }

  private static Integer maxNetSeg(String s1,int mi){
    s1 = new StringBuffer(s1).reverse().toString();

    if(s1.indexOf("1")!=-1){
      int i = s1.indexOf("1");
      return mi+calculate(i);
    }else {
      return 255;
    }

  }
  private static Integer subMaskNum(String s1){
    if(s1.lastIndexOf("1")!=-1){
      int i = s1.lastIndexOf("1") + 1;
      return i;
    }
    return 0;

  }
}

Java根据网段计算子网掩码，起始IP，结束IP

/**
 * IP的相关计算
 * @author zengchaowang
 * @version 1.0
 *
 */
public class IpCaculate {

	/**
	 * 根据掩码位数计算掩码
	 * @param maskIndex 掩码位
	 * @return 子网掩码
	 */
	public static String getNetMask(String maskIndex) {
		StringBuilder mask = new StringBuilder();
		Integer inetMask = 0;
		try {
			inetMask = Integer.parseInt(maskIndex);
		} catch (NumberFormatException e) {
			System.out.println(e.getMessage());
			return null;
		}
		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] += 1 << 8 - num2;
		}
		for (int i = 0; i < 4; i++) {
			if (i == 3) {
				mask.append(array[i]);
			} else {
				mask.append(array[i] + ".");
			}
		}
		return mask.toString();
	}

	/**
	 * 根据网段计算起始IP 网段格式:x.x.x.x/x
	 * 一个网段0一般为网络地址,255一般为广播地址.
	 * 起始IP计算:网段与掩码相与之后加一的IP地址
	 * @param segment 网段
	 * @return 起始IP
	 */
	public static String getStartIp(String segment) {
		StringBuffer startIp = new StringBuffer();
		if (segment == null) {
			return null;
		}
		String arr[] = segment.split("/");
		String ip = arr[0];
		String maskIndex = arr[1];
		String mask = IpCaculate.getNetMask(maskIndex);
		if (4 != ip.split("\\.").length || mask == null) {
			return null;
		}
		int ipArray[] = new int[4];
		int netMaskArray[] = new int[4];
		for (int i = 0; i < 4; i++) {
			try {
				ipArray[i] = Integer.parseInt(ip.split("\\.")[i]);
				netMaskArray[i] = Integer.parseInt(mask.split("\\.")[i]);
				if (ipArray[i] > 255 || ipArray[i] < 0 || netMaskArray[i] > 255 || netMaskArray[i] < 0) {
					return null;
				}
				ipArray[i] = ipArray[i] & netMaskArray[i];
				if(i==3){
					startIp.append(ipArray[i]+1);
				}else{
					startIp.append(ipArray[i]+".");
				}
			} catch (NumberFormatException e) {
				System.out.println(e.getMessage());
			}
		}
		 return startIp.toString();
	}

	/**
	 * 根据网段计算结束IP
	 * @param segment
	 * @return 结束IP
	 */
	public static String getEndIp(String segment) {
		StringBuffer endIp=new StringBuffer();
		String startIp = getStartIp(segment);
		if (segment == null) {
			return null;
		}
		String arr[] = segment.split("/");
		String maskIndex = arr[1];
		//实际需要的IP个数
	  int hostNumber = 0;
	  int startIpArray[] = new int[4];
		try {
			hostNumber=1<<32-(Integer.parseInt(maskIndex));
			for (int i = 0; i <4; i++) {
				startIpArray[i] = Integer.parseInt(startIp.split("\\.")[i]);
		    if(i == 3){
		    	startIpArray[i] = startIpArray[i] - 1;
		      break;
		    }
		  }
			startIpArray[3] = startIpArray[3] + (hostNumber - 1);
		} catch (NumberFormatException e) {
			System.out.println(e.getMessage());
		}

		if(startIpArray[3] >255){
	    int k = startIpArray[3] / 256;
	    startIpArray[3] = startIpArray[3] % 256;
	    startIpArray[2] = startIpArray[2] + k;
	  }
	  if(startIpArray[2] > 255){
	    int j = startIpArray[2] / 256;
	    startIpArray[2] = startIpArray[2] % 256;
	    startIpArray[1] = startIpArray[1] + j;
	      if(startIpArray[1] > 255){
	        int k = startIpArray[1] / 256;
	        startIpArray[1] = startIpArray[1] % 256;
	        startIpArray[0] = startIpArray[0] + k;
	      }
	    }
	  for(int i = 0; i < 4; i++){
	    if(i == 3){
	    	startIpArray[i] = startIpArray[i] - 1;
	    }
	    if("" == endIp.toString()||endIp.length()==0){
	    	endIp.append(startIpArray[i]);
	    }else{
	    	endIp.append("." + startIpArray[i]);
	    }
	  }
		return endIp.toString();
	}
}

根据网段计算起始IP 网段格式:x.x.x.x/x

网段内需要的IP数量为：2的（32-掩码位）次方个。

因为一个网段0一般为网络地址,255一般为广播地址， 所以第一个可用IP起始IP计算:网段与掩码相与之后加一的IP地址，结束IP为通过计算需要的所有IP数然后做累加运算，超过256则进位进行运算。

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