Java tutorial
/* * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.net; import java.io.IOException; import java.io.InvalidObjectException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.ObjectStreamException; import java.io.ObjectStreamField; /** * * This class implements an IP Socket Address (IP address + port number) * It can also be a pair (hostname + port number), in which case an attempt * will be made to resolve the hostname. If resolution fails then the address * is said to be <I>unresolved</I> but can still be used on some circumstances * like connecting through a proxy. * <p> * It provides an immutable object used by sockets for binding, connecting, or * as returned values. * <p> * The <i>wildcard</i> is a special local IP address. It usually means "any" * and can only be used for {@code bind} operations. * * @see java.net.Socket * @see java.net.ServerSocket * @since 1.4 */ public class InetSocketAddress extends SocketAddress { // Private implementation class pointed to by all public methods. private static class InetSocketAddressHolder { // The hostname of the Socket Address private String hostname; // The IP address of the Socket Address private InetAddress addr; // The port number of the Socket Address private int port; private InetSocketAddressHolder(String hostname, InetAddress addr, int port) { this.hostname = hostname; this.addr = addr; this.port = port; } private int getPort() { return port; } private InetAddress getAddress() { return addr; } private String getHostName() { if (hostname != null) return hostname; if (addr != null) return addr.getHostName(); return null; } private String getHostString() { if (hostname != null) return hostname; if (addr != null) { if (addr.holder().getHostName() != null) return addr.holder().getHostName(); else return addr.getHostAddress(); } return null; } private boolean isUnresolved() { return addr == null; } @Override public String toString() { if (isUnresolved()) { return hostname + ":" + port; } else { return addr.toString() + ":" + port; } } @Override public final boolean equals(Object obj) { if (obj == null || !(obj instanceof InetSocketAddressHolder)) return false; InetSocketAddressHolder that = (InetSocketAddressHolder) obj; boolean sameIP; if (addr != null) sameIP = addr.equals(that.addr); else if (hostname != null) sameIP = (that.addr == null) && hostname.equalsIgnoreCase(that.hostname); else sameIP = (that.addr == null) && (that.hostname == null); return sameIP && (port == that.port); } @Override public final int hashCode() { if (addr != null) return addr.hashCode() + port; if (hostname != null) return hostname.toLowerCase().hashCode() + port; return port; } } private final transient InetSocketAddressHolder holder; private static final long serialVersionUID = 5076001401234631237L; private static int checkPort(int port) { if (port < 0 || port > 0xFFFF) throw new IllegalArgumentException("port out of range:" + port); return port; } private static String checkHost(String hostname) { if (hostname == null) throw new IllegalArgumentException("hostname can't be null"); return hostname; } /** * Creates a socket address where the IP address is the wildcard address * and the port number a specified value. * <p> * A valid port value is between 0 and 65535. * A port number of {@code zero} will let the system pick up an * ephemeral port in a {@code bind} operation. * * @param port The port number * @throws IllegalArgumentException if the port parameter is outside the specified * range of valid port values. */ public InetSocketAddress(int port) { this(InetAddress.anyLocalAddress(), port); } /** * * Creates a socket address from an IP address and a port number. * <p> * A valid port value is between 0 and 65535. * A port number of {@code zero} will let the system pick up an * ephemeral port in a {@code bind} operation. * <P> * A {@code null} address will assign the <i>wildcard</i> address. * * @param addr The IP address * @param port The port number * @throws IllegalArgumentException if the port parameter is outside the specified * range of valid port values. */ public InetSocketAddress(InetAddress addr, int port) { holder = new InetSocketAddressHolder(null, addr == null ? InetAddress.anyLocalAddress() : addr, checkPort(port)); } /** * * Creates a socket address from a hostname and a port number. * <p> * An attempt will be made to resolve the hostname into an InetAddress. * If that attempt fails, the address will be flagged as <I>unresolved</I>. * <p> * If there is a security manager, its {@code checkConnect} method * is called with the host name as its argument to check the permission * to resolve it. This could result in a SecurityException. * <P> * A valid port value is between 0 and 65535. * A port number of {@code zero} will let the system pick up an * ephemeral port in a {@code bind} operation. * * @param hostname the Host name * @param port The port number * @throws IllegalArgumentException if the port parameter is outside the range * of valid port values, or if the hostname parameter is {@code null}. * @throws SecurityException if a security manager is present and * permission to resolve the host name is * denied. * @see #isUnresolved() */ public InetSocketAddress(String hostname, int port) { checkHost(hostname); InetAddress addr = null; String host = null; try { addr = InetAddress.getByName(hostname); } catch (UnknownHostException e) { host = hostname; } holder = new InetSocketAddressHolder(host, addr, checkPort(port)); } // private constructor for creating unresolved instances private InetSocketAddress(int port, String hostname) { holder = new InetSocketAddressHolder(hostname, null, port); } /** * * Creates an unresolved socket address from a hostname and a port number. * <p> * No attempt will be made to resolve the hostname into an InetAddress. * The address will be flagged as <I>unresolved</I>. * <p> * A valid port value is between 0 and 65535. * A port number of {@code zero} will let the system pick up an * ephemeral port in a {@code bind} operation. * * @param host the Host name * @param port The port number * @throws IllegalArgumentException if the port parameter is outside * the range of valid port values, or if the hostname * parameter is {@code null}. * @see #isUnresolved() * @return an {@code InetSocketAddress} representing the unresolved * socket address * @since 1.5 */ public static InetSocketAddress createUnresolved(String host, int port) { return new InetSocketAddress(checkPort(port), checkHost(host)); } /** * @serialField hostname String * @serialField addr InetAddress * @serialField port int */ private static final ObjectStreamField[] serialPersistentFields = { new ObjectStreamField("hostname", String.class), new ObjectStreamField("addr", InetAddress.class), new ObjectStreamField("port", int.class) }; private void writeObject(ObjectOutputStream out) throws IOException { // Don't call defaultWriteObject() ObjectOutputStream.PutField pfields = out.putFields(); pfields.put("hostname", holder.hostname); pfields.put("addr", holder.addr); pfields.put("port", holder.port); out.writeFields(); } private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { // Don't call defaultReadObject() ObjectInputStream.GetField oisFields = in.readFields(); final String oisHostname = (String) oisFields.get("hostname", null); final InetAddress oisAddr = (InetAddress) oisFields.get("addr", null); final int oisPort = oisFields.get("port", -1); // Check that our invariants are satisfied checkPort(oisPort); if (oisHostname == null && oisAddr == null) throw new InvalidObjectException("hostname and addr " + "can't both be null"); InetSocketAddressHolder h = new InetSocketAddressHolder(oisHostname, oisAddr, oisPort); UNSAFE.putReference(this, FIELDS_OFFSET, h); } private void readObjectNoData() throws ObjectStreamException { throw new InvalidObjectException("Stream data required"); } private static final jdk.internal.misc.Unsafe UNSAFE = jdk.internal.misc.Unsafe.getUnsafe(); private static final long FIELDS_OFFSET = UNSAFE.objectFieldOffset(InetSocketAddress.class, "holder"); /** * Gets the port number. * * @return the port number. */ public final int getPort() { return holder.getPort(); } /** * Gets the {@code InetAddress}. * * @return the InetAddress or {@code null} if it is unresolved. */ public final InetAddress getAddress() { return holder.getAddress(); } /** * Gets the {@code hostname}. * Note: This method may trigger a name service reverse lookup if the * address was created with a literal IP address. * * @return the hostname part of the address. */ public final String getHostName() { return holder.getHostName(); } /** * Returns the hostname, or the String form of the address if it * doesn't have a hostname (it was created using a literal). * This has the benefit of <b>not</b> attempting a reverse lookup. * * @return the hostname, or String representation of the address. * @since 1.7 */ public final String getHostString() { return holder.getHostString(); } /** * Checks whether the address has been resolved or not. * * @return {@code true} if the hostname couldn't be resolved into * an {@code InetAddress}. */ public final boolean isUnresolved() { return holder.isUnresolved(); } /** * Constructs a string representation of this InetSocketAddress. * This String is constructed by calling toString() on the InetAddress * and concatenating the port number (with a colon). If the address * is unresolved then the part before the colon will only contain the hostname. * * @return a string representation of this object. */ @Override public String toString() { return holder.toString(); } /** * Compares this object against the specified object. * The result is {@code true} if and only if the argument is * not {@code null} and it represents the same address as * this object. * <p> * Two instances of {@code InetSocketAddress} represent the same * address if both the InetAddresses (or hostnames if it is unresolved) and port * numbers are equal. * If both addresses are unresolved, then the hostname and the port number * are compared. * * Note: Hostnames are case insensitive. e.g. "FooBar" and "foobar" are * considered equal. * * @param obj the object to compare against. * @return {@code true} if the objects are the same; * {@code false} otherwise. * @see java.net.InetAddress#equals(java.lang.Object) */ @Override public final boolean equals(Object obj) { if (obj == null || !(obj instanceof InetSocketAddress)) return false; return holder.equals(((InetSocketAddress) obj).holder); } /** * Returns a hashcode for this socket address. * * @return a hash code value for this socket address. */ @Override public final int hashCode() { return holder.hashCode(); } }