javaenvutils.java

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/*
 *  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.
 *
 */
package org.apache.tools.ant.util;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.util.Vector;
import org.apache.tools.ant.taskdefs.condition.Os;

/**
 * A set of helper methods related to locating executables or checking
 * conditons of a given Java installation.
 *
 * @since Ant 1.5
 */
public final class JavaEnvUtils {

    private JavaEnvUtils() {
    }

    /** Are we on a DOS-based system */
    private static final boolean IS_DOS = Os.isFamily("dos");
    /** Are we on Novell NetWare */
    private static final boolean IS_NETWARE = Os.isName("netware");
    /** Are we on AIX */
    private static final boolean IS_AIX = Os.isName("aix");

    /** shortcut for System.getProperty("java.home") */
    private static final String JAVA_HOME = System.getProperty("java.home");

    /** FileUtils instance for path normalization */
    private static final FileUtils FILE_UTILS = FileUtils.getFileUtils();

    /** Version of currently running VM. */
    private static String javaVersion;

    /** floating version of the JVM */
    private static int javaVersionNumber;

    /** Version constant for Java 1.0 */
    public static final String JAVA_1_0 = "1.0";
    /** Number Version constant for Java 1.0 */
    public static final int VERSION_1_0 = 10;

    /** Version constant for Java 1.1 */
    public static final String JAVA_1_1 = "1.1";
    /** Number Version constant for Java 1.1 */
    public static final int VERSION_1_1 = 11;

    /** Version constant for Java 1.2 */
    public static final String JAVA_1_2 = "1.2";
    /** Number Version constant for Java 1.2 */
    public static final int VERSION_1_2 = 12;

    /** Version constant for Java 1.3 */
    public static final String JAVA_1_3 = "1.3";
    /** Number Version constant for Java 1.3 */
    public static final int VERSION_1_3 = 13;

    /** Version constant for Java 1.4 */
    public static final String JAVA_1_4 = "1.4";
    /** Number Version constant for Java 1.4 */
    public static final int VERSION_1_4 = 14;

    /** Version constant for Java 1.5 */
    public static final String JAVA_1_5 = "1.5";
    /** Number Version constant for Java 1.5 */
    public static final int VERSION_1_5 = 15;

    /** Version constant for Java 1.6 */
    public static final String JAVA_1_6 = "1.6";
    /** Number Version constant for Java 1.6 */
    public static final int VERSION_1_6 = 16;

    /** Whether this is the Kaffe VM */
    private static boolean kaffeDetected;

    /** array of packages in the runtime */
    private static Vector jrePackages;


    static {

        // Determine the Java version by looking at available classes
        // java.net.Proxy was introduced in JDK 1.5
        // java.lang.CharSequence was introduced in JDK 1.4
        // java.lang.StrictMath was introduced in JDK 1.3
        // java.lang.ThreadLocal was introduced in JDK 1.2
        // java.lang.Void was introduced in JDK 1.1
        // Count up version until a NoClassDefFoundError ends the try

        try {
            javaVersion = JAVA_1_0;
            javaVersionNumber = VERSION_1_0;
            Class.forName("java.lang.Void");
            javaVersion = JAVA_1_1;
            javaVersionNumber++;
            Class.forName("java.lang.ThreadLocal");
            javaVersion = JAVA_1_2;
            javaVersionNumber++;
            Class.forName("java.lang.StrictMath");
            javaVersion = JAVA_1_3;
            javaVersionNumber++;
            Class.forName("java.lang.CharSequence");
            javaVersion = JAVA_1_4;
            javaVersionNumber++;
            Class.forName("java.net.Proxy");
            javaVersion = JAVA_1_5;
            javaVersionNumber++;
            Class.forName("java.util.ServiceLoader");
            javaVersion = JAVA_1_6;
            javaVersionNumber++;
        } catch (Throwable t) {
            // swallow as we've hit the max class version that
            // we have
        }
        kaffeDetected = false;
        try {
            Class.forName("kaffe.util.NotImplemented");
            kaffeDetected = true;
        } catch (Throwable t) {
            // swallow as this simply doesn't seem to be Kaffe
        }
    }

    /**
     * Returns the version of Java this class is running under.
     * @return the version of Java as a String, e.g. "1.1"
     */
    public static String getJavaVersion() {
        return javaVersion;
    }


    /**
     * Returns the version of Java this class is running under.
     * This number can be used for comparisions; it will always be
     * @return the version of Java as a number 10x the major/minor,
     * e.g Java1.5 has a value of 15
     */
    public static int getJavaVersionNumber() {
        return javaVersionNumber;
    }

    /**
     * Compares the current Java version to the passed in String -
     * assumes the argument is one of the constants defined in this
     * class.
     * Note that Ant now requires JDK 1.2+ so {@link #JAVA_1_0} and
     * {@link #JAVA_1_1} need no longer be tested for.
     * @param version the version to check against the current version.
     * @return true if the version of Java is the same as the given version.
     * @since Ant 1.5
     */
    public static boolean isJavaVersion(String version) {
        return javaVersion.equals(version);
    }

    /**
     * Compares the current Java version to the passed in String -
     * assumes the argument is one of the constants defined in this
     * class.
     * Note that Ant now requires JDK 1.2+ so {@link #JAVA_1_0} and
     * {@link #JAVA_1_1} need no longer be tested for.
     * @param version the version to check against the current version.
     * @return true if the version of Java is the same or higher than the
     * given version.
     * @since Ant 1.7
     */
    public static boolean isAtLeastJavaVersion(String version) {
        return javaVersion.compareTo(version) >= 0;
    }

    /**
     * Checks whether the current Java VM is Kaffe.
     * @return true if the current Java VM is Kaffe.
     * @since Ant 1.6.3
     * @see <a href="http://www.kaffe.org/">http://www.kaffe.org/</a>
     */
    public static boolean isKaffe() {
        return kaffeDetected;
    }

    /**
     * Finds an executable that is part of a JRE installation based on
     * the java.home system property.
     *
     * <p><code>java</code>, <code>keytool</code>,
     * <code>policytool</code>, <code>orbd</code>, <code>rmid</code>,
     * <code>rmiregistry</code>, <code>servertool</code> and
     * <code>tnameserv</code> are JRE executables on Sun based
     * JRE's.</p>
     *
     * <p>You typically find them in <code>JAVA_HOME/jre/bin</code> if
     * <code>JAVA_HOME</code> points to your JDK installation.  JDK
     * &lt; 1.2 has them in the same directory as the JDK
     * executables.</p>
     * @param command the java executable to find.
     * @return the path to the command.
     * @since Ant 1.5
     */
    public static String getJreExecutable(String command) {
        if (IS_NETWARE) {
            // Extrapolating from:
            // "NetWare may have a "java" in that directory, but 99% of
            // the time, you don't want to execute it" -- Jeff Tulley
            // <[e-mail]>
            return command;
        }

        File jExecutable = null;

        if (IS_AIX) {
            // On IBM's JDK 1.2 the directory layout is different, 1.3 follows