如果两个IP在同一网络中,请使用Java进行测试

时间:2011-12-19 00:00:38

标签: java ip subnet

如何根据子网掩码测试两个IP是否在同一网络中?

例如,我有IP 1.2.3.4和1.2.4.3:如果掩码是255.0.0.0或255.255.0.0或甚至是255.255.248.0,则两者都在同一网络中,但如果掩码是255.255.255.0则不在同一网络中。

3 个答案:

答案 0 :(得分:14)

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个对象:

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;

}

答案 1 :(得分:5)

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

答案 2 :(得分:0)

此解决方案也适用于IPv4 / IPv6。

static boolean sameNetwork(final byte[] x, final byte[] y, final int mask) {
    if(x == y) return true;
    if(x == null || y == null) return false;
    if(x.length != y.length) return false;
    final int bits  = mask &   7;
    final int bytes = mask >>> 3;
    for(int i=0;i<bytes;i++)  if(x[i] != y[i]) return false;
    final int shift = 8 - bits;
    if(bits != 0 && x[bytes]>>>shift != y[bytes]>>>shift) return false;
    return true;
}
static boolean sameNetwork(final InetAddress a, final InetAddress b, final int mask) {
    return sameNetwork(a.getAddress(), b.getAddress(), mask);
}