Java example source code file (MonitoredVmUtil.java)

This example Java source code file (MonitoredVmUtil.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

is_attachable, is_kernel_vm, monitoredvmutil, monitorexception, string, stringmonitor, unknown

The MonitoredVmUtil.java Java example source code

/*
 * Copyright (c) 2004, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.jvmstat.monitor;

/**
 * Utility class proving concenience methods for extracting various
 * information from an MonitoredVm object.
 *
 * @author Brian Doherty
 * @since 1.5
 */
public class MonitoredVmUtil {

    /**
     * Private constructor - prevent instantiation.
     */
    private MonitoredVmUtil() { }

    /**
     * Return the Java Virtual Machine Version.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the version of the target JVM or the
     *                  the string "Unknown" if the version cannot be
     *                  determined.
     */
    public static String vmVersion(MonitoredVm vm) throws MonitorException {
        StringMonitor ver =
               (StringMonitor)vm.findByName("java.property.java.vm.version");
        return (ver == null) ? "Unknown" : ver.stringValue();
    }

    /**
     * Return the command line for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the command line of the target Java
     *                  application or the the string "Unknown" if the
     *                  command line cannot be determined.
     */
    public static String commandLine(MonitoredVm vm) throws MonitorException {
        StringMonitor cmd = (StringMonitor)vm.findByName("sun.rt.javaCommand");
        return (cmd == null) ? "Unknown" : cmd.stringValue();
    }

    /**
     * Return the arguments to the main class for the target Java application.
     * Returns the arguments to the main class. If the arguments can't be
     * found, the string "Unknown" is returned.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the arguments to the main class for the
     *                  target Java application or the the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String mainArgs(MonitoredVm vm) throws MonitorException {
        String commandLine = commandLine(vm);

        int firstSpace = commandLine.indexOf(' ');
        if (firstSpace > 0) {
            return commandLine.substring(firstSpace + 1);
        } else if (commandLine.compareTo("Unknown") == 0) {
            return commandLine;
        } else {
            return null;
        }
    }

    /**
     * Return the main class for the target Java application.
     * Returns the main class or the name of the jar file if the application
     * was started with the <em>-jar option.
     *
     * @param vm the target MonitoredVm
     * @param fullPath include the full path to Jar file, where applicable
     * @return String - contains the main class of the target Java
     *                  application or the the string "Unknown" if the
     *                  command line cannot be determined.
     */
    public static String mainClass(MonitoredVm vm, boolean fullPath)
                         throws MonitorException {
        String commandLine = commandLine(vm);
        String arg0 = commandLine;

        int firstSpace = commandLine.indexOf(' ');
        if (firstSpace > 0) {
            arg0 = commandLine.substring(0, firstSpace);
        }
        if (!fullPath) {
            /*
             * can't use File.separator() here because the separator
             * for the target jvm may be different than the separator
             * for the monitoring jvm.
             */
            int lastFileSeparator = arg0.lastIndexOf('/');
            if (lastFileSeparator > 0) {
                 return arg0.substring(lastFileSeparator + 1);
            }

            lastFileSeparator = arg0.lastIndexOf('\\');
            if (lastFileSeparator > 0) {
                 return arg0.substring(lastFileSeparator + 1);
            }

            int lastPackageSeparator = arg0.lastIndexOf('.');
            if (lastPackageSeparator > 0) {
                 return arg0.substring(lastPackageSeparator + 1);
            }
        }
        return arg0;
    }

    /**
     * Return the JVM arguments for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the arguments passed to the JVM for the
     *                  target Java application or the the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String jvmArgs(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmArgs = (StringMonitor)vm.findByName("java.rt.vmArgs");
        return (jvmArgs == null) ? "Unknown" : jvmArgs.stringValue();
    }

    /**
     * Return the JVM flags for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the flags passed to the JVM for the
     *                  target Java application or the the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String jvmFlags(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmFlags =
               (StringMonitor)vm.findByName("java.rt.vmFlags");
        return (jvmFlags == null) ? "Unknown" : jvmFlags.stringValue();
    }

    // Index of the sun.rt.jvmCapabilities counter
    private static int IS_ATTACHABLE = 0;
    private static int IS_KERNEL_VM  = 1;

    /**
     * Returns true if the VM supports attach-on-demand.
     *
     * @param vm the target MonitoredVm
     */
    public static boolean isAttachable(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmCapabilities =
               (StringMonitor)vm.findByName("sun.rt.jvmCapabilities");
        if (jvmCapabilities == null) {
             return false;
        } else {
             return jvmCapabilities.stringValue().charAt(IS_ATTACHABLE) == '1';
        }
    }

}