org.eclipse.persistence.internal.helper.JavaVersion Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation
EclipseLink build based upon Git transaction 346465e
There is a newer version: 5.0.0-B07
/*******************************************************************************
 * Copyright (c) 1998, 2016 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Tomas Kraus, Peter Benedikovic - initial API and implementation
 ******************************************************************************/
package org.eclipse.persistence.internal.helper;

import java.security.AccessController;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.eclipse.persistence.internal.security.PrivilegedAccessHelper;
import org.eclipse.persistence.internal.security.PrivilegedGetSystemProperty;

/**
 * Java version storage class. Used for version numbers retrieved from
 * Java specification version string. Stored version is in
 * <major>.<minor> format.
 * @author Tomas Kraus, Peter Benedikovic
 */
public final class JavaVersion {

    /** JavaEE platform version elements separator character. */
    public static final char SEPARATOR = '.';

    /** JavaEE platform patch version element separator character. */
    public static final char PATCH_SEPARATOR = '_';

    /** Java VM version system property name. */
    private static final String VM_VERSION_PROPERTY = "java.specification.version";

    /**
     * Java specification version output regular expression pattern.
     * Regular expression contains tokens to read individual version number
     * components. Expected input is string like
     * java version "1.6" or 9.
     */
    private static final String VM_VERSION_PATTERN =
            "[^0-9]*([0-9]+)(\\.([0-9]+))*";

    /** Number of Matcher groups (REGEX tokens) expected in Java VM
     *  version output. */
    private static final int VM_MIN_VERSION_TOKENS = 1;

    /**
     * Retrieves Java specification version {@see String} from JDK system property.
     * @return Java specification version {@see String} from JDK system property.
     */
    public static String vmVersionString() {
        if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()) {
            return AccessController.doPrivileged(new PrivilegedGetSystemProperty(VM_VERSION_PROPERTY));
        }
        return System.getProperty(VM_VERSION_PROPERTY);
    }

    /**
     * Java specification version detector.
     * Retrieves Java specification version from JDK system property. Version string should
     * look like:
     * "MA.MI"
     * 
     * Where
     * MA is major version number,
     * 
MI is minor version number
     * 
     * Label java version is parsed as non case sensitive.
     */
    public static JavaVersion vmVersion() {
        final String version = vmVersionString();
        final Pattern pattern = Pattern.compile(VM_VERSION_PATTERN);
        final Matcher matcher = pattern.matcher(version);
        int major = 0, minor = 0;
        if (matcher.find()) {
            major = Integer.parseInt(matcher.group(1));
            String min = matcher.group(VM_MIN_VERSION_TOKENS + 2);
            minor = min != null ? Integer.parseInt(min) : 0;
        }
        return new JavaVersion(major, minor);
    }

    /** Major version number. */
    private final int major;

    /** Minor version number. */
    private final int minor;

    /**
     * Constructs an instance of Java specification version number.
     * @param major    Major version number.
     * @param minor    Minor version number.
     */
    public JavaVersion(final int major, final int minor) {
        this.major = major;
        this.minor = minor;
    }

    /**
     * Get major version number.
     * @return Major version number.
     */
    public final int getMajor() {
        return major;
    }

    /**
     * Get minor version number.
     * @return Minor version number.
     */
    public final int getMinor() {
        return minor;
    }

    /**
     * Compares this JavaVersion object against another one.
     * @param version JavaVersion object to compare with
     *                this object.
     * @return Compare result:
     *         Value 1 if this value
     *         is greater than supplied version value.
     *         
Value -1 if this value
     *         is lesser than supplied version value.
     *         
Value 0 if both this value
     *         and supplied version values are equal.
     *         
     */
    public final int comapreTo(final JavaVersion version) {
        return this.major > version.major ? 1 :
                this.major < version.major ? -1 :
                this.minor > version.minor ? 1 :
                this.minor < version.minor ? -1 : 0;
    }

    /**
     * Return String representation of Java VM version object.
     * @return Java VM version string.
     */
    @Override
    public final String toString() {
        final StringBuilder sb = new StringBuilder(3);
        sb.append(major);
        sb.append(SEPARATOR);
        sb.append(minor);
        return sb.toString();
    }

    /**
     * Return {@link JavaSEPlatform} matching this Java SE specification version.
     * @return {@link JavaSEPlatform} matching this Java SE specification version.
     */
    public final JavaSEPlatform toPlatform() {
        return JavaSEPlatform.toValue(major, minor);
    }

}