如果两个IP在同一网络中,请使用Java进行测试

Question

如何根据子网掩码测试两个IP是否在同一网络中？

比如我有IP地址1.2.3.4 1.2.4.3和:两者都是在同一个网络中,如果掩码是255.0.0.0或255.255.0.0甚至255.255.248.0但如果掩码为255.255.255.0 ..

Answer 1

试试这个方法:

public static boolean sameNetwork(String ip1, String ip2, String mask) 
throws Exception {

    byte[] a1 = InetAddress.getByName(ip1).getAddress();
    byte[] a2 = InetAddress.getByName(ip2).getAddress();
    byte[] m = InetAddress.getByName(mask).getAddress();

    for (int i = 0; i < a1.length; i++)
        if ((a1[i] & m[i]) != (a2[i] & m[i]))
            return false;

    return true;

}

并像这样使用它:

sameNetwork("1.2.3.4", "1.2.4.3", "255.255.255.0")
> false

编辑:

如果您已将IP作为InetAddress对象:

public static boolean sameNetwork(InetAddress ip1, InetAddress ip2, String mask) 
throws Exception {

    byte[] a1 = ip1.getAddress();
    byte[] a2 = ip2.getAddress();
    byte[] m = InetAddress.getByName(mask).getAddress();

    for (int i = 0; i < a1.length; i++)
        if ((a1[i] & m[i]) != (a2[i] & m[i]))
            return false;

    return true;

}

Answer 2

足够简单:mask & ip1 == mask & ip2- 您必须将IP全部解释为单个数字,但这应该是显而易见的.