systemutils.java

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     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_MAC_OSX = getOSMatches("Mac OS X");

    /**
     * <p>Is <code>true</code> if this is OS/2.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_OS2 = getOSMatches("OS/2");

    /**
     * <p>Is <code>true</code> if this is Solaris.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_SOLARIS = getOSMatches("Solaris");

    /**
     * <p>Is <code>true</code> if this is SunOS.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_SUN_OS = getOSMatches("SunOS");

    /**
     * <p>Is <code>true</code> if this is Windows.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_WINDOWS = getOSMatches("Windows");

    /**
     * <p>Is <code>true</code> if this is Windows 2000.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_WINDOWS_2000 = getOSMatches("Windows", "5.0");

    /**
     * <p>Is <code>true</code> if this is Windows 95.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_WINDOWS_95 = getOSMatches("Windows 9", "4.0");
    // JDK 1.2 running on Windows98 returns 'Windows 95', hence the above

    /**
     * <p>Is <code>true</code> if this is Windows 98.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_WINDOWS_98 = getOSMatches("Windows 9", "4.1");
    // JDK 1.2 running on Windows98 returns 'Windows 95', hence the above

    /**
     * <p>Is <code>true</code> if this is Windows ME.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_WINDOWS_ME = getOSMatches("Windows", "4.9");
    // JDK 1.2 running on WindowsME may return 'Windows 95', hence the above

    /**
     * <p>Is <code>true</code> if this is Windows NT.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_WINDOWS_NT = getOSMatches("Windows NT");
    // Windows 2000 returns 'Windows 2000' but may suffer from same JDK1.2 problem

    /**
     * <p>Is <code>true</code> if this is Windows XP.</p>
     *
     * <p>The field will return <code>false</code> if <code>OS_NAME</code> is
     * <code>null</code>.</p>
     * 
     * @since 2.0
     */
    public static final boolean IS_OS_WINDOWS_XP = getOSMatches("Windows", "5.1");
    // Windows XP returns 'Windows 2000' just for fun...

    //-----------------------------------------------------------------------    
    /**
     * <p>SystemUtils instances should NOT be constructed in standard
     * programming. Instead, the class should be used as
     * <code>SystemUtils.FILE_SEPARATOR</code>.</p>
     *
     * <p>This constructor is public to permit tools that require a JavaBean
     * instance to operate.</p>
     */
    public SystemUtils() {
    }
    
    //-----------------------------------------------------------------------    
    /**
     * <p>Gets the Java version number as a <code>float</code>.</p>
     *
     * <p>Example return values:</p>
     * <ul>
     *  <li><code>1.2f</code> for JDK 1.2
     *  <li><code>1.31f</code> for JDK 1.3.1
     * </ul>
     * 
     * @return the version, for example 1.31f for JDK 1.3.1
     * @deprecated Use {@link #JAVA_VERSION_FLOAT} instead.
     *             Method will be removed in Commons Lang 3.0.
     */
    public static float getJavaVersion() {
        return JAVA_VERSION_FLOAT;
    }

    /**
     * <p>Gets the Java version number as a <code>float</code>.</p>
     *
     * <p>Example return values:</p>
     * <ul>
     *  <li><code>1.2f</code> for JDK 1.2
     *  <li><code>1.31f</code> for JDK 1.3.1
     * </ul>
     * 
     * <p>Patch releases are not reported.
     * Zero is returned if {@link #JAVA_VERSION} is <code>null</code>.</p>
     * 
     * @return the version, for example 1.31f for JDK 1.3.1
     */
    private static float getJavaVersionAsFloat() {
        if (JAVA_VERSION == null) {
            return 0f;
        }
        String str = JAVA_VERSION.substring(0, 3);
        if (JAVA_VERSION.length() >= 5) {
            str = str + JAVA_VERSION.substring(4, 5);
        }
        return Float.parseFloat(str);
    }
    
    /**
     * <p>Gets the Java version number as an <code>int</code>.</p>
     *
     * <p>Example return values:</p>
     * <ul>
     *  <li><code>120</code> for JDK 1.2
     *  <li><code>131</code> for JDK 1.3.1
     * </ul>
     * 
     * <p>Patch releases are not reported.
     * Zero is returned if {@link #JAVA_VERSION} is <code>null</code>.</p>
     * 
     * @return the version, for example 131 for JDK 1.3.1
     */
    private static int getJavaVersionAsInt() {
        if (JAVA_VERSION == null) {
            return 0;
        }
        String str = JAVA_VERSION.substring(0, 1);
        str = str + JAVA_VERSION.substring(2, 3);
        if (JAVA_VERSION.length() >= 5) {
            str = str + JAVA_VERSION.substring(4, 5);
        } else {
            str = str + "0";
        }
        return Integer.parseInt(str);
    }

    /**
     * <p>Decides if the java version matches.</p>
     * 
     * @param versionPrefix  the prefix for the java version
     * @return true if matches, or false if not or can't determine
     */
    private static boolean getJavaVersionMatches(String versionPrefix) {
        if (JAVA_VERSION == null) {
            return false;
        }
        return JAVA_VERSION.startsWith(versionPrefix);
    }    
    
    /**
     * <p>Decides if the operating system matches.</p>
     * 
     * @param osNamePrefix  the prefix for the os name
     * @return true if matches, or false if not or can't determine
     */
    private static boolean getOSMatches(String osNamePrefix) {
        if (OS_NAME == null) {
            return false;
        }
        return OS_NAME.startsWith(osNamePrefix);
    }    

    /**
     * <p>Decides if the operating system matches.</p>
     * 
     * @param osNamePrefix  the prefix for the os name
     * @param osVersionPrefix  the prefix for the version
     * @return true if matches, or false if not or can't determine
     */
    private static boolean getOSMatches(String osNamePrefix, String osVersionPrefix) {
        if (OS_NAME == null || OS_VERSION == null) {
            return false;
        }
        return OS_NAME.startsWith(osNamePrefix) && OS_VERSION.startsWith(osVersionPrefix);
    }    

    //-----------------------------------------------------------------------
    /**
     * <p>Gets a System property, defaulting to <code>null</code> if the property
     * cannot be read.</p>
     *
     * <p>If a <code>SecurityException</code> is caught, the return
     * value is <code>null</code> and a message is written to <code>System.err</code>.</p>
     * 
     * @param property the system property name
     * @return the system property value or <code>null</code> if a security problem occurs
     */
    private static String getSystemProperty(String property) {
        try {
            return System.getProperty(property);
        } catch (SecurityException ex) {
            // we are not allowed to look at this property
            System.err.println(
                "Caught a SecurityException reading the system property '" + property 
                + "'; the SystemUtils property value will default to null."
            );
            return null;
        }
    }    
    
    /**
     * <p>Is the Java version at least the requested version.</p>
     *
     * <p>Example input:</p>
     * <ul>
     *  <li><code>1.2f</code> to test for JDK 1.2</li>
     *  <li><code>1.31f</code> to test for JDK 1.3.1</li>
     * </ul>
     * 
     * @param requiredVersion  the required version, for example 1.31f
     * @return <code>true</code> if the actual version is equal or greater
     *  than the required version
     */
    public static boolean isJavaVersionAtLeast(float requiredVersion) {
        return (JAVA_VERSION_FLOAT >= requiredVersion);
    }
    
    /**
     * <p>Is the Java version at least the requested version.</p>
     *
     * <p>Example input:</p>
     * <ul>
     *  <li><code>120</code> to test for JDK 1.2 or greater</li>
     *  <li><code>131</code> to test for JDK 1.3.1 or greater</li>
     * </ul>
     * 
     * @param requiredVersion  the required version, for example 131
     * @return <code>true</code> if the actual version is equal or greater
     *  than the required version
     * @since 2.0
     */
    public static boolean isJavaVersionAtLeast(int requiredVersion) {
        return (JAVA_VERSION_INT >= requiredVersion);
    }
    
}