jdk1.5获取子网广播地址

用jdk1.6可以很容易的获取子网广播地址，但是1.5并没有实现相应的方法。我写了如下代码，已经在window xp和linux redhat中测试通过。
第一个类：实现子网广播地址

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;
import java.util.Vector;

public class SubnetAddress{
    private static Process p;      
    
    public void SubnetAddress(){        
    }
        
    /**
     * 获取本机IP
     * @return
     */
    private String getIpAddressFromLinux(){
        Enumeration netInterfaces;
        String result=null;
        try {
            netInterfaces = NetworkInterface.getNetworkInterfaces();    
            InetAddress ip = null;
            while(netInterfaces.hasMoreElements()){
                NetworkInterface ni=(NetworkInterface)netInterfaces.nextElement();
                ip=(InetAddress) ni.getInetAddresses().nextElement();
                if( !ip.isLoopbackAddress()&& ip.getHostAddress().indexOf(":")==-1)
                {
                    result=ip.getHostAddress();
                    break;
                }
                else                
                     ip=null;
               }
        } catch (SocketException e) {            
            e.printStackTrace();
        }
        return result;
    }
    
    /**
     * 获取本机IP
     * @return
     */
    private String getIpAddress(){
        String result=null;
        InetAddress inet;
        try {
            inet = InetAddress.getLocalHost();
            result = inet.getHostAddress();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }        
        return result;
    }
    
    /**
     * 使用ipconfig/all命令
     * 获取windows系统上的子网掩码
     * @return
     */
    private String getSubnetAddressForWindow(){
        String cmd = "cmd.exe /c ipconfig/all"; //window下获取子网掩码的命令
        String find ="Subnet Mask";//子网掩码的提示        
        
        Vector ipConfigs;  
        ipConfigs = execute(cmd);      
        Object[] ipConfigArray=ipConfigs.toArray();
        String result = null;
        for(int i=0;i<ipConfigArray.length;i++){
            String ipConfig = ipConfigArray[i].toString();
            if(!ipConfig.equalsIgnoreCase("") && ipConfig.indexOf(find)!=-1){
                String[] subnet = ipConfig.split(":");
                result = subnet[1].substring(1);
                break;
            }
        }
        return result;
    } 
    
    /**
     * 使用ifconfig命令
     * 获取linux系统上的子网掩码
     * @return
     */
    private String getSubnetAddressForLinux(){                
        String cmd = "ifconfig"; //linux下获取子网掩码的命令
        String find = "Mask";//子网掩码的提示
            
        Vector ipConfigs;  
        ipConfigs = execute(cmd);      
        Object[] ipConfigArray=ipConfigs.toArray();
        String result = null;
        for(int i=0;i<ipConfigArray.length;i++){
            String ipConfig = ipConfigArray[i].toString();
            if(!ipConfig.equalsIgnoreCase("") && ipConfig.indexOf(find)!=-1){
                
                String[] subnet1 = ipConfig.split(find);
                String[] subnet = subnet1[1].split(":");
                result = subnet[1];                
                break;
            }
        }
        return result;
    } 
    
    /**
     * 执行命令
     * @param shellCommand
     * @return
     */
    private Vector execute(String shellCommand){             
        try{
            Start(shellCommand);             
            Vector vResult=new Vector();             
            DataInputStream in=new DataInputStream(p.getInputStream());             
            BufferedReader reader=new BufferedReader(new InputStreamReader(in));             
            String line;  
            do{
                line=reader.readLine();  
                if(line==null){  
                    break;  
                }  
                else{  
                    vResult.addElement(line);  
                }  
            }while(true);  
            reader.close();  
            return   vResult;  
          }catch(Exception e){             
              return null;  
          }  
    } 
    
    private void Start(String shellCommand){         
        try{  
            if(p!=null){  
                p.destroy();  
                p=null;    
            }  
            Runtime sys=Runtime.getRuntime();  
            p=sys.exec(shellCommand);  
        }catch(Exception   e){  
            e.printStackTrace();  
        }  
    }  
        
    /**
     * 根据本机IP和子网掩码，计算子网广播地址
     * @param ip 本机ip
     * @param subnet 本机子网掩码
     * @return
     */
     public String calculate() {
         String os = System.getProperty("os.name").substring(0, 3);
         String subnet;
            if(os.equalsIgnoreCase("win")){
                subnet = getSubnetAddressForWindow();
            }
            else{
                subnet = getSubnetAddressForLinux();
            }            
         String ip = getIpAddress();        
         
         String[] ips = ip.split("\\."); 
         String[] subnets = subnet.split("\\.");
         StringBuffer sb = new StringBuffer();
         for(int i = 0; i < ips.length; i++) {
             ips[i] = String.valueOf((~Integer.parseInt(subnets[i]))|(Integer.parseInt(ips[i])));
             sb.append(turnToStr(Integer.parseInt(ips[i])));
             if(i != (ips.length-1))
                 sb.append(".");
         }                                    
         return turnToIp(sb.toString());
    }

     /**
      * 把带符号整形转换为二进制
      * @param num
      * @return
      */
    private String turnToStr(int num) {
        String str = "";
        str = Integer.toBinaryString(num);          
        int len = 8 - str.length();
        // 如果二进制数据少于8位,在前面补零.
        for (int i = 0; i < len; i++) {
            str = "0" + str;
        }
        //如果num为负数，转为二进制的结果有32位，如1111 1111 1111 1111 1111 1111 1101 1110
        //则只取最后的8位.
        if (len < 0)
            str = str.substring(24, 32);
        return str;
    }    
    
    /**
     * 把二进制形式的ip，转换为十进制形式的ip
     * @param str
     * @return
     */
    private String turnToIp(String str){
        String[] ips = str.split("\\.");
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < ips.length; i++) {
            sb.append(turnToInt(ips[i]));
            sb.append(".");
        }          
        sb.deleteCharAt(sb.length() - 1);
        return sb.toString();
    }

    /**
     * 把二进制转换为十进制
     * @param str
     * @return
     */
    private int turnToInt(String str){
        int total = 0;
        int top = str.length();
        for (int i = 0; i < str.length(); i++) {
            String h = String.valueOf(str.charAt(i));
            top--;
            total += ((int) Math.pow(2, top)) * (Integer.parseInt(h));
        }
        return total;
    }
}

第二个类：调用上个类中的方法

import java.net.SocketException;
import java.net.UnknownHostException;

public class test{
    public static void main(String[] args) throws SocketException, UnknownHostException{
        System.out.println(System.getProperty("os.name"));
        SubnetAddress sa = new SubnetAddress();
        String s = sa.calculate();
        System.out.println(s);
    }
}