/*
* $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/ProtocolVersion.java $
* $Revision: 609106 $
* $Date: 2008-01-05 01:15:42 -0800 (Sat, 05 Jan 2008) $
*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.http;
import java.io.Serializable;
import org.apache.http.util.CharArrayBuffer;
/**
* Represents a protocol version, as specified in RFC 2616.
* RFC 2616 specifies only HTTP versions, like "HTTP/1.1" and "HTTP/1.0".
* RFC 3261 specifies a message format that is identical to HTTP except
* for the protocol name. It defines a protocol version "SIP/2.0".
* There are some nitty-gritty differences between the interpretation
* of versions in HTTP and SIP. In those cases, HTTP takes precedence.
* <p>
* This class defines a protocol version as a combination of
* protocol name, major version number, and minor version number.
* Note that {@link #equals} and {@link #hashCode} are defined as
* final here, they cannot be overridden in derived classes.
*
* @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
* @author <a href="mailto:rolandw at apache.org">Roland Weber</a>
*
* @version $Revision: 609106 $
*/
public class ProtocolVersion implements Serializable, Cloneable {
private static final long serialVersionUID = 8950662842175091068L;
/** Name of the protocol. */
protected final String protocol;
/** Major version number of the protocol */
protected final int major;
/** Minor version number of the protocol */
protected final int minor;
/**
* Create a protocol version designator.
*
* @param protocol the name of the protocol, for example "HTTP"
* @param major the major version number of the protocol
* @param minor the minor version number of the protocol
*/
public ProtocolVersion(String protocol, int major, int minor) {
if (protocol == null) {
throw new IllegalArgumentException
("Protocol name must not be null.");
}
if (major < 0) {
throw new IllegalArgumentException
("Protocol major version number must not be negative.");
}
if (minor < 0) {
throw new IllegalArgumentException
("Protocol minor version number may not be negative");
}
this.protocol = protocol;
this.major = major;
this.minor = minor;
}
/**
* Returns the name of the protocol.
*
* @return the protocol name
*/
public final String getProtocol() {
return protocol;
}
/**
* Returns the major version number of the protocol.
*
* @return the major version number.
*/
public final int getMajor() {
return major;
}
/**
* Returns the minor version number of the HTTP protocol.
*
* @return the minor version number.
*/
public final int getMinor() {
return minor;
}
/**
* Obtains a specific version of this protocol.
* This can be used by derived classes to instantiate themselves instead
* of the base class, and to define constants for commonly used versions.
* <br/>
* The default implementation in this class returns <code>this</code>
* if the version matches, and creates a new {@link ProtocolVersion}
* otherwise.
*
* @param major the major version
* @param minor the minor version
*
* @return a protocol version with the same protocol name
* and the argument version
*/
public ProtocolVersion forVersion(int major, int minor) {
if ((major == this.major) && (minor == this.minor)) {
return this;
}
// argument checking is done in the constructor
return new ProtocolVersion(this.protocol, major, minor);
}
/**
* Obtains a hash code consistent with {@link #equals}.
*
* @return the hashcode of this protocol version
*/
public final int hashCode() {
return this.protocol.hashCode() ^ (this.major * 100000) ^ this.minor;
}
/**
* Checks equality of this protocol version with an object.
* The object is equal if it is a protocl version with the same
* protocol name, major version number, and minor version number.
* The specific class of the object is <i>not</i> relevant,
* instances of derived classes with identical attributes are
* equal to instances of the base class and vice versa.
*
* @param obj the object to compare with
*
* @return <code>true</code> if the argument is the same protocol version,
* <code>false</code> otherwise
*/
public final boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof ProtocolVersion)) {
return false;
}
ProtocolVersion that = (ProtocolVersion) obj;
return ((this.protocol.equals(that.protocol)) &&
(this.major == that.major) &&
(this.minor == that.minor));
}
/**
* Checks whether this protocol can be compared to another one.
* Only protocol versions with the same protocol name can be
* {@link #compareToVersion compared}.
*
* @param that the protocol version to consider
*
* @return <code>true</code> if {@link #compareToVersion compareToVersion}
* can be called with the argument, <code>false</code> otherwise
*/
public boolean isComparable(ProtocolVersion that) {
return (that != null) && this.protocol.equals(that.protocol);
}
/**
* Compares this protocol version with another one.
* Only protocol versions with the same protocol name can be compared.
* This method does <i>not</i> define a total ordering, as it would be
* required for {@link java.lang.Comparable}.
*
* @param that the protocl version to compare with
*
* @return a negative integer, zero, or a positive integer
* as this version is less than, equal to, or greater than
* the argument version.
*
* @throws IllegalArgumentException
* if the argument has a different protocol name than this object,
* or if the argument is <code>null</code>
*/
public int compareToVersion(ProtocolVersion that) {
if (that == null) {
throw new IllegalArgumentException
("Protocol version must not be null.");
}
if (!this.protocol.equals(that.protocol)) {
throw new IllegalArgumentException
("Versions for different protocols cannot be compared. " +
this + " " + that);
}
int delta = getMajor() - that.getMajor();
if (delta == 0) {
delta = getMinor() - that.getMinor();
}
return delta;
}
/**
* Tests if this protocol version is greater or equal to the given one.
*
* @param version the version against which to check this version
*
* @return <code>true</code> if this protocol version is
* {@link #isComparable comparable} to the argument
* and {@link #compareToVersion compares} as greater or equal,
* <code>false</code> otherwise
*/
public final boolean greaterEquals(ProtocolVersion version) {
return isComparable(version) && (compareToVersion(version) >= 0);
}
/**
* Tests if this protocol version is less or equal to the given one.
*
* @param version the version against which to check this version
*
* @return <code>true</code> if this protocol version is
* {@link #isComparable comparable} to the argument
* and {@link #compareToVersion compares} as less or equal,
* <code>false</code> otherwise
*/
public final boolean lessEquals(ProtocolVersion version) {
return isComparable(version) && (compareToVersion(version) <= 0);
}
/**
* Converts this protocol version to a string.
*
* @return a protocol version string, like "HTTP/1.1"
*/
public String toString() {
CharArrayBuffer buffer = new CharArrayBuffer(16);
buffer.append(this.protocol);
buffer.append('/');
buffer.append(Integer.toString(this.major));
buffer.append('.');
buffer.append(Integer.toString(this.minor));
return buffer.toString();
}
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
}