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Adds javadoc to NetworkConstants

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Also renames some internal variables to be more understandable
No API changes! :)
This commit is contained in:
Cruz Julian Bishop 2012-06-27 17:41:49 +10:00 committed by Trustin Lee
parent 9cc9f4e1ec
commit 2653facd3b
1 changed files with 54 additions and 15 deletions
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69
common/src/main/java/io/netty/util/NetworkConstants.java
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@ -24,62 +24,101 @@ import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;
/**
* A class that holds a number of network-related constants.
*/
public final class NetworkConstants {
/**
* The {@link InetAddress} representing the host machine
*
* We cache this because some machines take almost forever to return from
* {@link InetAddress}.getLocalHost(). This may be due to incorrect
* configuration of the hosts and DNS client configuration files.
*/
public static final InetAddress LOCALHOST;
/**
* The loopback {@link NetworkInterface} on the current machine
*/
public static final NetworkInterface LOOPBACK_IF;
/**
* The logger being used by this class
*/
private static final InternalLogger logger =
InternalLoggerFactory.getInstance(NetworkConstants.class);
static {
// We cache this because some machine takes almost forever to return
// from InetAddress.getLocalHost(). I think it's due to the incorrect
// /etc/hosts or /etc/resolve.conf.
//Start the process of discovering localhost
InetAddress localhost = null;
try {
//Let's start by getting localhost automatically
localhost = InetAddress.getLocalHost();
} catch (UnknownHostException e) {
//No? That's okay.
try {
//Try to force an IPv4 localhost address
localhost = InetAddress.getByAddress(new byte[] { 127, 0, 0, 1 });
} catch (UnknownHostException e1) {
//No? Okay. You must be using IPv6
try {
//Try to force an IPv6 localhost address
localhost = InetAddress.getByAddress(
new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 });
} catch (UnknownHostException e2) {
logger.error("Failed to resolve localhost", e2);
//No? Okay.
logger.error("Failed to resolve localhost - Incorrect network configuration?", e2);
}
}
}
//Set the localhost constant
LOCALHOST = localhost;
NetworkInterface loopbackIf;
//Prepare to get the local NetworkInterface
NetworkInterface loopbackInterface;
try {
loopbackIf = NetworkInterface.getByInetAddress(LOCALHOST);
//Automatically get the loopback interface
loopbackInterface = NetworkInterface.getByInetAddress(LOCALHOST);
} catch (SocketException e) {
loopbackIf = null;
//No? Alright. There is a backup!
loopbackInterface = null;
}
// If null is returned, iterate over all the available network interfaces.
if (loopbackIf == null) {
//Check to see if a network interface was not found
if (loopbackInterface == null) {
try {
for (Enumeration<NetworkInterface> e = NetworkInterface.getNetworkInterfaces();
e.hasMoreElements();) {
NetworkInterface nif = e.nextElement();
if (nif.isLoopback()) {
loopbackIf = nif;
//Start iterating over all network interfaces
for (Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
interfaces.hasMoreElements();) {
//Get the "next" interface
NetworkInterface networkInterface = interfaces.nextElement();
//Check to see if the interface is a loopback interface
if (networkInterface.isLoopback()) {
//Phew! The loopback interface was found.
loopbackInterface = networkInterface;
//No need to keep iterating
break;
}
}
} catch (SocketException e) {
//Nope. Can't do anything else, sorry!
logger.error("Failed to enumerate network interfaces", e);
}
}
LOOPBACK_IF = loopbackIf;
//Set the loopback interface constant
LOOPBACK_IF = loopbackInterface;
}
/**
* A constructor to stop this class being constructed.
*/
private NetworkConstants() {
// Unused
}