Java - IP地址与数字之间互转

摘自 android.net.NetworkUtils.java 源码

1.转换 IPv4 地址：把 IP 地址换为 int

    /**     * Convert a IPv4 address from an InetAddress to an integer     * @param inetAddr is an InetAddress corresponding to the IPv4 address     * @return the IP address as an integer in network byte order     */    public static int inetAddressToInt(InetAddress inetAddr)            throws IllegalArgumentException {        byte [] addr = inetAddr.getAddress();        if (addr.length != 4) {            throw new IllegalArgumentException("Not an IPv4 address");        }        return ((addr[3] & 0xff) << 24) | ((addr[2] & 0xff) << 16) |                ((addr[1] & 0xff) << 8) | (addr[0] & 0xff);    }

2.转换 IPv4 地址：把 init 转换为 IP 地址

    /**     * Convert a IPv4 address from an integer to an InetAddress.     * @param hostAddress an int corresponding to the IPv4 address in network byte order     */    public static InetAddress intToInetAddress(int hostAddress) {        byte[] addressBytes = { (byte)(0xff & hostAddress),                                (byte)(0xff & (hostAddress >> 8)),                                (byte)(0xff & (hostAddress >> 16)),                                (byte)(0xff & (hostAddress >> 24)) };        try {           return InetAddress.getByAddress(addressBytes);        } catch (UnknownHostException e) {           throw new AssertionError();        }    }