用java获得广播地址

王朝java/jsp·作者佚名  2006-01-10
窄屏简体版  字體: |||超大  

如何计算网络的广播地址呢,下面就是算法:

假如计算机的IP位址是192.15.156.205,子网掩码是255.255.255.224,

先把子网掩码255.255.255.224做 NOT 运算﹐可以得出﹕

00000000.00000000.00000000.00011111

然后再和IP做一次 OR 运算﹐就可以得到 Broadcast Address:

11000000.00001111.10011100.11001101 OR 00000000.00000000.00000000.00011111

(192.15.156.205 OR 255.255.255.224)

得出﹕ 11000000.00001111.10011100.11011111

(192.15.156.223)

192.15.156.223就是那个子网的广播地址了.

下面就是实现这个算法的java类清单.

public class BroadcastAddr {

private String netmask = "";

private String netaddr = "";

private String netbroadcastaddr = "";

/**

* @param args

*/

public static void main(String[] args) {

BroadcastAddr info = new BroadcastAddr();

try {

System.out.println(Inet4Address.getByName("ooad-navysea")

.toString());

System.out.println(Inet4Address.getAllByName("localhost").length);

} catch (UnknownHostException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

info.setNetaddr("192.168.1.106");

info.setNetmask("255.255.255.0");

info.execCalc();

System.out.println(info.getNetbroadcastaddr());

}

public String getNetaddr() {

return netaddr;

}

public void setNetaddr(String netaddr) {

this.netaddr = netaddr;

}

public String getNetbroadcastaddr() {

return netbroadcastaddr;

}

public void setNetbroadcastaddr(String netbroadcastaddr) {

this.netbroadcastaddr = netbroadcastaddr;

}

public String getNetmask() {

return netmask;

}

public void setNetmask(String netmask) {

this.netmask = netmask;

}

public void execCalc() {

String[] tm = this.getNetmask().split("\\.");

StringBuffer sb = new StringBuffer();

for (int i = 0; i < tm.length; i++) {

tm[i] = String.valueOf(~(Integer.parseInt(tm[i])));

}

String[] tm2 = this.getNetaddr().split("\\.");

for (int i = 0; i < tm.length; i++) {

tm[i] = String.valueOf((Integer.parseInt(tm2[i]))

| (Integer.parseInt(tm[i])));

}

for (int i = 0; i < tm.length; i++) {

sb.append(intTOstr(tm[i]));

sb.append(".");

}

// sb.delete(sb.length()-1,sb.length());

sb.deleteCharAt(sb.length() - 1);

this.netbroadcastaddr = parseIp(sb.toString());

}

private String intTOstr(int num) {

String tm = "";

tm = Integer.toBinaryString(num);

int c = 8 - tm.length();

// 如果二进制数据少于8位,在前面补零.

for (int i = 0; i < c; i++) {

tm = "0" + tm;

}

// 1111 1111 1111 1111 1111 1111 1101 1110

// 如果小于零,则只取最后的8位.

if (c < 0)

tm = tm.substring(24, 32);

return tm;

}

private String intTOstr(String num) {

return intTOstr(Integer.parseInt(num));

}

private String parseIp(String fbg) {

String[] tm = fbg.split("\\.");

StringBuffer sb = new StringBuffer();

for (int i = 0; i < tm.length; i++) {

sb.append(strToint(tm[i]));

sb.append(".");

}

// sb.delete(sb.length()-1,1);

sb.deleteCharAt(sb.length() - 1);

return sb.toString();

}

/**

* 把二进制数转换为十进制.

*

* @param str

* @return

*/

private int strToint(String str) {

int total = 0;

int top = str.length();

for (int i = 0; i < str.length(); i++) {

// System.out.println(str.charAt(i)+str.substring(i,i+1));

String h = String.valueOf(str.charAt(i));

// System.out.println(h+":"+top+":"+total);

top--;

total += ((int) Math.pow(2, top)) * (Integer.parseInt(h));

}

return total;

}

}

 
 
 
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