Java tutorial
/* * Copyright (C) 2011 The Guava Authors * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.google.common.net; import static com.google.common.base.Preconditions.checkArgument; import static com.google.common.base.Preconditions.checkNotNull; import static com.google.common.base.Preconditions.checkState; import com.google.common.annotations.Beta; import com.google.common.annotations.GwtCompatible; import com.google.common.base.Objects; import com.google.common.base.Strings; import java.io.Serializable; import javax.annotation.Nullable; import javax.annotation.concurrent.Immutable; /** * An immutable representation of a host and port. * * <p>Example usage: * <pre> * HostAndPort hp = HostAndPort.fromString("[2001:db8::1]") * .withDefaultPort(80) * .requireBracketsForIPv6(); * hp.getHostText(); // returns "2001:db8::1" * hp.getPort(); // returns 80 * hp.toString(); // returns "[2001:db8::1]:80" * </pre> * * <p>Here are some examples of recognized formats: * <ul> * <li>example.com * <li>example.com:80 * <li>192.0.2.1 * <li>192.0.2.1:80 * <li>[2001:db8::1] - {@link #getHostText()} omits brackets * <li>[2001:db8::1]:80 - {@link #getHostText()} omits brackets * <li>2001:db8::1 - Use {@link #requireBracketsForIPv6()} to prohibit this * </ul> * * <p>Note that this is not an exhaustive list, because these methods are only * concerned with brackets, colons, and port numbers. Full validation of the * host field (if desired) is the caller's responsibility. * * @author Paul Marks * @since 10.0 */ @Beta @Immutable @GwtCompatible public final class HostAndPort implements Serializable { /** Magic value indicating the absence of a port number. */ private static final int NO_PORT = -1; /** Hostname, IPv4/IPv6 literal, or unvalidated nonsense. */ private final String host; /** Validated port number in the range [0..65535], or NO_PORT */ private final int port; /** True if the parsed host has colons, but no surrounding brackets. */ private final boolean hasBracketlessColons; private HostAndPort(String host, int port, boolean hasBracketlessColons) { this.host = host; this.port = port; this.hasBracketlessColons = hasBracketlessColons; } /** * Returns the portion of this {@code HostAndPort} instance that should * represent the hostname or IPv4/IPv6 literal. * * <p>A successful parse does not imply any degree of sanity in this field. * For additional validation, see the {@link HostSpecifier} class. */ public String getHostText() { return host; } /** Return true if this instance has a defined port. */ public boolean hasPort() { return port >= 0; } /** * Get the current port number, failing if no port is defined. * * @return a validated port number, in the range [0..65535] * @throws IllegalStateException if no port is defined. You can use * {@link #withDefaultPort(int)} to prevent this from occurring. */ public int getPort() { checkState(hasPort()); return port; } /** * Returns the current port number, with a default if no port is defined. */ public int getPortOrDefault(int defaultPort) { return hasPort() ? port : defaultPort; } /** * Build a HostAndPort instance from separate host and port values. * * <p>Note: Non-bracketed IPv6 literals are allowed. * Use {@link #requireBracketsForIPv6()} to prohibit these. * * @param host the host string to parse. Must not contain a port number. * @param port a port number from [0..65535] * @return if parsing was successful, a populated HostAndPort object. * @throws IllegalArgumentException if {@code host} contains a port number, * or {@code port} is out of range. */ public static HostAndPort fromParts(String host, int port) { checkArgument(isValidPort(port), "Port out of range: %s", port); HostAndPort parsedHost = fromString(host); checkArgument(!parsedHost.hasPort(), "Host has a port: %s", host); return new HostAndPort(parsedHost.host, port, parsedHost.hasBracketlessColons); } /** * Build a HostAndPort instance from a host only. * * <p>Note: Non-bracketed IPv6 literals are allowed. * Use {@link #requireBracketsForIPv6()} to prohibit these. * * @param host the host-only string to parse. Must not contain a port number. * @return if parsing was successful, a populated HostAndPort object. * @throws IllegalArgumentException if {@code host} contains a port number. * @since 17.0 */ public static HostAndPort fromHost(String host) { HostAndPort parsedHost = fromString(host); checkArgument(!parsedHost.hasPort(), "Host has a port: %s", host); return parsedHost; } /** * Split a freeform string into a host and port, without strict validation. * * Note that the host-only formats will leave the port field undefined. You * can use {@link #withDefaultPort(int)} to patch in a default value. * * @param hostPortString the input string to parse. * @return if parsing was successful, a populated HostAndPort object. * @throws IllegalArgumentException if nothing meaningful could be parsed. */ public static HostAndPort fromString(String hostPortString) { checkNotNull(hostPortString); String host; String portString = null; boolean hasBracketlessColons = false; if (hostPortString.startsWith("[")) { String[] hostAndPort = getHostAndPortFromBracketedHost(hostPortString); host = hostAndPort[0]; portString = hostAndPort[1]; } else { int colonPos = hostPortString.indexOf(':'); if (colonPos >= 0 && hostPortString.indexOf(':', colonPos + 1) == -1) { // Exactly 1 colon. Split into host:port. host = hostPortString.substring(0, colonPos); portString = hostPortString.substring(colonPos + 1); } else { // 0 or 2+ colons. Bare hostname or IPv6 literal. host = hostPortString; hasBracketlessColons = (colonPos >= 0); } } int port = NO_PORT; if (!Strings.isNullOrEmpty(portString)) { // Try to parse the whole port string as a number. // JDK7 accepts leading plus signs. We don't want to. checkArgument(!portString.startsWith("+"), "Unparseable port number: %s", hostPortString); try { port = Integer.parseInt(portString); } catch (NumberFormatException e) { throw new IllegalArgumentException("Unparseable port number: " + hostPortString); } checkArgument(isValidPort(port), "Port number out of range: %s", hostPortString); } return new HostAndPort(host, port, hasBracketlessColons); } /** * Parses a bracketed host-port string, throwing IllegalArgumentException if parsing fails. * * @param hostPortString the full bracketed host-port specification. Post might not be specified. * @return an array with 2 strings: host and port, in that order. * @throws IllegalArgumentException if parsing the bracketed host-port string fails. */ private static String[] getHostAndPortFromBracketedHost(String hostPortString) { int colonIndex = 0; int closeBracketIndex = 0; checkArgument(hostPortString.charAt(0) == '[', "Bracketed host-port string must start with a bracket: %s", hostPortString); colonIndex = hostPortString.indexOf(':'); closeBracketIndex = hostPortString.lastIndexOf(']'); checkArgument(colonIndex > -1 && closeBracketIndex > colonIndex, "Invalid bracketed host/port: %s", hostPortString); String host = hostPortString.substring(1, closeBracketIndex); if (closeBracketIndex + 1 == hostPortString.length()) { return new String[] { host, "" }; } else { checkArgument(hostPortString.charAt(closeBracketIndex + 1) == ':', "Only a colon may follow a close bracket: %s", hostPortString); for (int i = closeBracketIndex + 2; i < hostPortString.length(); ++i) { checkArgument(Character.isDigit(hostPortString.charAt(i)), "Port must be numeric: %s", hostPortString); } return new String[] { host, hostPortString.substring(closeBracketIndex + 2) }; } } /** * Provide a default port if the parsed string contained only a host. * * You can chain this after {@link #fromString(String)} to include a port in * case the port was omitted from the input string. If a port was already * provided, then this method is a no-op. * * @param defaultPort a port number, from [0..65535] * @return a HostAndPort instance, guaranteed to have a defined port. */ public HostAndPort withDefaultPort(int defaultPort) { checkArgument(isValidPort(defaultPort)); if (hasPort() || port == defaultPort) { return this; } return new HostAndPort(host, defaultPort, hasBracketlessColons); } /** * Generate an error if the host might be a non-bracketed IPv6 literal. * * <p>URI formatting requires that IPv6 literals be surrounded by brackets, * like "[2001:db8::1]". Chain this call after {@link #fromString(String)} * to increase the strictness of the parser, and disallow IPv6 literals * that don't contain these brackets. * * <p>Note that this parser identifies IPv6 literals solely based on the * presence of a colon. To perform actual validation of IP addresses, see * the {@link InetAddresses#forString(String)} method. * * @return {@code this}, to enable chaining of calls. * @throws IllegalArgumentException if bracketless IPv6 is detected. */ public HostAndPort requireBracketsForIPv6() { checkArgument(!hasBracketlessColons, "Possible bracketless IPv6 literal: %s", host); return this; } @Override public boolean equals(@Nullable Object other) { if (this == other) { return true; } if (other instanceof HostAndPort) { HostAndPort that = (HostAndPort) other; return Objects.equal(this.host, that.host) && this.port == that.port && this.hasBracketlessColons == that.hasBracketlessColons; } return false; } @Override public int hashCode() { return Objects.hashCode(host, port, hasBracketlessColons); } /** Rebuild the host:port string, including brackets if necessary. */ @Override public String toString() { // "[]:12345" requires 8 extra bytes. StringBuilder builder = new StringBuilder(host.length() + 8); if (host.indexOf(':') >= 0) { builder.append('[').append(host).append(']'); } else { builder.append(host); } if (hasPort()) { builder.append(':').append(port); } return builder.toString(); } /** Return true for valid port numbers. */ private static boolean isValidPort(int port) { return port >= 0 && port <= 65535; } private static final long serialVersionUID = 0; }