Usually, you don't have to worry too much about Internet addresses—the numerical host addresses that consist of four bytes (or, with IPv6, 16 bytes) such as 132.163.4.102. However, you can use the InetAddress class if you need to convert between host names and Internet addresses.
The java.net package supports IPv6 Internet addresses, provided the host operating system does.
The static getByName method returns an InetAddress object of a host. For example,
InetAddress address = InetAddress.getByName("time-A.timefreq.bldrdoc.gov");
returns an InetAddress object that encapsulates the sequence of four bytes 132.163.4.104. You can access the bytes with the getAddress method.
Byte[] addressBytes = address.getAddress();
Some host names with a lot of traffic correspond to multiple Internet addresses, to facilitate load balancing. For example, at the time of this writing, the host name java.sun.com corresponds to three different Internet addresses. One of them is picked at random when the host is accessed. You can get all hosts with the getAllByName method.
InetAddress[] addresses = InetAddress.getAllByName(host);
Finally, you sometimes need the address of the local host. If you simply ask for the address of localhost, you always get the local loopback address 127.0.0.1, which cannot be used by others to connect to your computer. Instead, use the static getLocalHost method to get the address of your local host.
InetAddress address = InetAddress.getLocalHost();
The java.net package supports IPv6 Internet addresses, provided the host operating system does.
The static getByName method returns an InetAddress object of a host. For example,
InetAddress address = InetAddress.getByName("time-A.timefreq.bldrdoc.gov");
returns an InetAddress object that encapsulates the sequence of four bytes 132.163.4.104. You can access the bytes with the getAddress method.
Byte[] addressBytes = address.getAddress();
Some host names with a lot of traffic correspond to multiple Internet addresses, to facilitate load balancing. For example, at the time of this writing, the host name java.sun.com corresponds to three different Internet addresses. One of them is picked at random when the host is accessed. You can get all hosts with the getAllByName method.
InetAddress[] addresses = InetAddress.getAllByName(host);
Finally, you sometimes need the address of the local host. If you simply ask for the address of localhost, you always get the local loopback address 127.0.0.1, which cannot be used by others to connect to your computer. Instead, use the static getLocalHost method to get the address of your local host.
InetAddress address = InetAddress.getLocalHost();