如何使用java获取网络上的所有IP地址？

Question

I am using InetAddress class for fetching IP address on my network.

The problem is that sometime I can not get some addresses and sometime the InetAddress not able to fetch single IP from network.

What can be the problem? Thanks

I have tried below code:

public void fatchAllNetworkIP() throws UnknownHostException, IOException
{
    System.out.println("Fetching IP...");

    InetAddress localhost = InetAddress.getLocalHost();
    byte[] ip = localhost.getAddress();

    for (int i = 1; i <= 254; i++)
    {
        ip[3] = (byte)i;
        InetAddress address = InetAddress.getByAddress(ip);

        if(address.isReachable(1000))
        {
            //JOptionPane.showMessageDialog(null, address);
            System.out.println("IP Address "+i+"is "+address);
        }
    }
}

Answer 1

尝试java.net.NetworkInterface ，获取所有可用的NetworkInterfaces，然后获取所有附加的InetAddresses

Answer 2

Try with this example for 192.168.xx,

public static void main(String args[]) throws UnknownHostException {

        byte[] ip = {(byte)192, (byte)168, 0, 0}; //Note: for 192.168.0.x addresses  
        for (int i = 1; i <= 254; i++)  
        {  
            ip[3] = (byte) i;  
            InetAddress address = InetAddress.getByAddress(ip);  
            System.out.printf("InetAddress1: %s\n", address);
        } 


    }

Answer 3

You need to change the timeout so that system can check if there is reply from network machine..

if(address.isReachable(2000)) {
    System.out.println("IP Address "+i+"is "+address);
}

if same problem will occur again then try increasing the timeout..