javan之ManagementFactory

/**
     * Returns the platform MXBean implementing
     * the given {@code mxbeanInterface} which is specified
     * to have one single instance in the Java virtual machine.
     * This method may return {@code null} if the management interface
     * is not implemented in the Java virtual machine (for example,
     * a Java virtual machine with no compilation system does not
     * implement {@link CompilationMXBean});
     * otherwise, this method is equivalent to calling:
     * <pre>
     *    {@link #getPlatformMXBeans(Class)
     *      getPlatformMXBeans(mxbeanInterface)}.get(0);
     * </pre>
     *
     * @param mxbeanInterface a management interface for a platform
     *     MXBean with one single instance in the Java virtual machine
     *     if implemented.
     *
     * @return the platform MXBean that implements
     * {@code mxbeanInterface}, or {@code null} if not exist.
     *
     * @throws IllegalArgumentException if {@code mxbeanInterface}
     * is not a platform management interface or
     * not a singleton platform MXBean.
     *
     * @since 1.7
     */
    public static <T extends PlatformManagedObject>
            T getPlatformMXBean(Class<T> mxbeanInterface) {
        PlatformComponent pc = PlatformComponent.getPlatformComponent(mxbeanInterface);
        if (pc == null)
            throw new IllegalArgumentException(mxbeanInterface.getName() +
                " is not a platform management interface");
        if (!pc.isSingleton())
            throw new IllegalArgumentException(mxbeanInterface.getName() +
                " can have zero or more than one instances");


        return pc.getSingletonMXBean(mxbeanInterface);

    }

/**
     * Returns the managed bean for the memory system of
     * the Java virtual machine.
     *
     * @return a {@link MemoryMXBean} object for the Java virtual machine.
     */
    public static MemoryMXBean getMemoryMXBean() {
        return ManagementFactoryHelper.getMemoryMXBean();
    }

 /**
     * Returns the managed bean for the thread system of
     * the Java virtual machine.
     *
     * @return a {@link ThreadMXBean} object for the Java virtual machine.
     */
    public static ThreadMXBean getThreadMXBean() {
        return ManagementFactoryHelper.getThreadMXBean();
    }

/**
     * Returns a list of {@link GarbageCollectorMXBean} objects
     * in the Java virtual machine.
     * The Java virtual machine may have one or more
     * <tt>GarbageCollectorMXBean</tt> objects.
     * It may add or remove <tt>GarbageCollectorMXBean</tt>
     * during execution.
     *
     * @return a list of <tt>GarbageCollectorMXBean</tt> objects.
     *
     */
    public static List<GarbageCollectorMXBean> getGarbageCollectorMXBeans() {
        return ManagementFactoryHelper.getGarbageCollectorMXBeans();
    }

/**
     * Returns a list of {@link MemoryPoolMXBean} objects in the
     * Java virtual machine.
     * The Java virtual machine can have one or more memory pools.
     * It may add or remove memory pools during execution.
     *
     * @return a list of <tt>MemoryPoolMXBean</tt> objects.
     *
     */
    public static List<MemoryPoolMXBean> getMemoryPoolMXBeans() {
        return ManagementFactoryHelper.getMemoryPoolMXBeans();
    }

operatingSystemMXBean = ManagementFactory.getPlatformMXBean(OperatingSystemMXBean.class);
        memoryMXBean = ManagementFactory.getMemoryMXBean();
        threadMXBean = ManagementFactory.getThreadMXBean();
        garbageCollectorMXBeanList = ManagementFactory.getGarbageCollectorMXBeans();
        memoryPoolMXBeanList = ManagementFactory.getMemoryPoolMXBeans();