+ * 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. + *
+ * + * @since 4.0 + */ +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. + *this
+ * 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 not 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 true if the argument is the same protocol version,
+ * false 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 true if {@link #compareToVersion compareToVersion}
+ * can be called with the argument, false 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 not 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 null
+ */
+ 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 true if this protocol version is
+ * {@link #isComparable comparable} to the argument
+ * and {@link #compareToVersion compares} as greater or equal,
+ * false 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 true if this protocol version is
+ * {@link #isComparable comparable} to the argument
+ * and {@link #compareToVersion compares} as less or equal,
+ * false 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();
+ }
+
+}