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 * Copyright (c) 1999, 2013, 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
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package javax.management;

import com.sun.jmx.defaults.JmxProperties;
import static com.sun.jmx.defaults.JmxProperties.JMX_INITIAL_BUILDER;
import static com.sun.jmx.defaults.JmxProperties.MBEANSERVER_LOGGER;
import com.sun.jmx.mbeanserver.GetPropertyAction;
import java.security.AccessController;
import java.security.Permission;
import java.util.ArrayList;
import java.util.logging.Level;
import javax.management.loading.ClassLoaderRepository;
import sun.reflect.misc.ReflectUtil;


Provides MBean server references.  There are no instances of
this class.
Since JMX 1.2 this class makes it possible to replace the default MBeanServer implementation. This is done using the MBeanServerBuilder class. The class of the initial MBeanServerBuilder to be instantiated can be specified through the javax.management.builder.initial system property. The specified class must be a public subclass of MBeanServerBuilder, and must have a public empty constructor. 
By default, if no value for that property is specified, an instance of javax.management.MBeanServerBuilder is created. Otherwise, the MBeanServerFactory attempts to load the specified class using 
  Thread.currentThread().getContextClassLoader(), or if that is null, Class.forName(). Then it creates an initial instance of that Class using Class.newInstance(). If any checked exception is raised during this process (e.g. ClassNotFoundException, InstantiationException) the MBeanServerFactory will propagate this exception from within a RuntimeException.
The javax.management.builder.initial system property is
consulted every time a new MBeanServer needs to be created, and the
class pointed to by that property is loaded. If that class is different
from that of the current MBeanServerBuilder, then a new MBeanServerBuilder
is created. Otherwise, the MBeanServerFactory may create a new
MBeanServerBuilder or reuse the current one.
If the class pointed to by the property cannot be
loaded, or does not correspond to a valid subclass of MBeanServerBuilder
then an exception is propagated, and no MBeanServer can be created until
the javax.management.builder.initial system property is reset to
valid value.
The MBeanServerBuilder makes it possible to wrap the MBeanServers
returned by the default MBeanServerBuilder implementation, for the purpose
of e.g. adding an additional security layer.
Since:
1.5/**
 * <p>Provides MBean server references.  There are no instances of
 * this class.</p>
 *
 * <p>Since JMX 1.2 this class makes it possible to replace the default
 * MBeanServer implementation. This is done using the
 * {@link javax.management.MBeanServerBuilder} class.
 * The class of the initial MBeanServerBuilder to be
 * instantiated can be specified through the
 * <b>javax.management.builder.initial</b> system property.
 * The specified class must be a public subclass of
 * {@link javax.management.MBeanServerBuilder}, and must have a public
 * empty constructor.
 * <p>By default, if no value for that property is specified, an instance of
 * {@link
 * javax.management.MBeanServerBuilder javax.management.MBeanServerBuilder}
 * is created. Otherwise, the MBeanServerFactory attempts to load the
 * specified class using
 * {@link java.lang.Thread#getContextClassLoader()
 *   Thread.currentThread().getContextClassLoader()}, or if that is null,
 * {@link java.lang.Class#forName(java.lang.String) Class.forName()}. Then
 * it creates an initial instance of that Class using
 * {@link java.lang.Class#newInstance()}. If any checked exception
 * is raised during this process (e.g.
 * {@link java.lang.ClassNotFoundException},
 * {@link java.lang.InstantiationException}) the MBeanServerFactory
 * will propagate this exception from within a RuntimeException.</p>
 *
 * <p>The <b>javax.management.builder.initial</b> system property is
 * consulted every time a new MBeanServer needs to be created, and the
 * class pointed to by that property is loaded. If that class is different
 * from that of the current MBeanServerBuilder, then a new MBeanServerBuilder
 * is created. Otherwise, the MBeanServerFactory may create a new
 * MBeanServerBuilder or reuse the current one.</p>
 *
 * <p>If the class pointed to by the property cannot be
 * loaded, or does not correspond to a valid subclass of MBeanServerBuilder
 * then an exception is propagated, and no MBeanServer can be created until
 * the <b>javax.management.builder.initial</b> system property is reset to
 * valid value.</p>
 *
 * <p>The MBeanServerBuilder makes it possible to wrap the MBeanServers
 * returned by the default MBeanServerBuilder implementation, for the purpose
 * of e.g. adding an additional security layer.</p>
 *
 * @since 1.5
 */
public class MBeanServerFactory {

    /*
     * There are no instances of this class so don't generate the
     * default public constructor.
     */
    private MBeanServerFactory() {

    }

    
The builder that will be used to construct MBeanServers.
/**
     * The builder that will be used to construct MBeanServers.
     *
     **/
    private static MBeanServerBuilder builder = null;

    /**
     * Provide a new {@link javax.management.MBeanServerBuilder}.
     * @param builder The new MBeanServerBuilder that will be used to
     *        create {@link javax.management.MBeanServer}s.
     * @exception IllegalArgumentException if the given builder is null.
     *
     * @exception SecurityException if there is a SecurityManager and
     * the caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("setMBeanServerBuilder")</code>.
     *
     **/
    // public static synchronized void
    //    setMBeanServerBuilder(MBeanServerBuilder builder) {
    //    checkPermission("setMBeanServerBuilder");
    //    MBeanServerFactory.builder = builder;
    // }

    /**
     * Get the current {@link javax.management.MBeanServerBuilder}.
     *
     * @return the current {@link javax.management.MBeanServerBuilder}.
     *
     * @exception SecurityException if there is a SecurityManager and
     * the caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("getMBeanServerBuilder")</code>.
     *
     **/
    // public static synchronized MBeanServerBuilder getMBeanServerBuilder() {
    //     checkPermission("getMBeanServerBuilder");
    //     return builder;
    // }

    
Remove internal MBeanServerFactory references to a created
MBeanServer. This allows the garbage collector to remove the
MBeanServer object.
Params:
mbeanServer – the MBeanServer object to remove.
Throws:
IllegalArgumentException – if
mbeanServer was not generated by one of the
createMBeanServer methods, or if
releaseMBeanServer was already called on it.
SecurityException – if there is a SecurityManager and
the caller's permissions do not include or imply MBeanServerPermission("releaseMBeanServer")./**
     * Remove internal MBeanServerFactory references to a created
     * MBeanServer. This allows the garbage collector to remove the
     * MBeanServer object.
     *
     * @param mbeanServer the MBeanServer object to remove.
     *
     * @exception java.lang.IllegalArgumentException if
     * <code>mbeanServer</code> was not generated by one of the
     * <code>createMBeanServer</code> methods, or if
     * <code>releaseMBeanServer</code> was already called on it.
     *
     * @exception SecurityException if there is a SecurityManager and
     * the caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("releaseMBeanServer")</code>.
     */
    public static void releaseMBeanServer(MBeanServer mbeanServer) {
        checkPermission("releaseMBeanServer");

        removeMBeanServer(mbeanServer);
    }

    
Return a new object implementing the MBeanServer interface
with a standard default domain name.  The default domain name
is used as the domain part in the ObjectName of MBeans when the
domain is specified by the user is null.
The standard default domain name is
DefaultDomain.
The MBeanServer reference is internally kept. This will
allow findMBeanServer to return a reference to
this MBeanServer object.
This method is equivalent to createMBeanServer(null).
Throws:
SecurityException – if there is a SecurityManager and the
caller's permissions do not include or imply MBeanServerPermission("createMBeanServer").
JMRuntimeException – if the property
javax.management.builder.initial exists but the class it names cannot be instantiated through a public no-argument constructor; or if the instantiated builder returns null from its 
newMBeanServerDelegate or newMBeanServer methods.
ClassCastException – if the property
javax.management.builder.initial exists and can be instantiated but is not assignment compatible with MBeanServerBuilder.
Returns:
the newly created MBeanServer./**
     * <p>Return a new object implementing the MBeanServer interface
     * with a standard default domain name.  The default domain name
     * is used as the domain part in the ObjectName of MBeans when the
     * domain is specified by the user is null.</p>
     *
     * <p>The standard default domain name is
     * <code>DefaultDomain</code>.</p>
     *
     * <p>The MBeanServer reference is internally kept. This will
     * allow <CODE>findMBeanServer</CODE> to return a reference to
     * this MBeanServer object.</p>
     *
     * <p>This method is equivalent to <code>createMBeanServer(null)</code>.
     *
     * @return the newly created MBeanServer.
     *
     * @exception SecurityException if there is a SecurityManager and the
     * caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("createMBeanServer")</code>.
     *
     * @exception JMRuntimeException if the property
     * <code>javax.management.builder.initial</code> exists but the
     * class it names cannot be instantiated through a public
     * no-argument constructor; or if the instantiated builder returns
     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate
     * newMBeanServerDelegate} or {@link
     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.
     *
     * @exception ClassCastException if the property
     * <code>javax.management.builder.initial</code> exists and can be
     * instantiated but is not assignment compatible with {@link
     * MBeanServerBuilder}.
     */
    public static MBeanServer createMBeanServer() {
        return createMBeanServer(null);
    }

    
Return a new object implementing the MBeanServer interface with the specified default domain name. The given domain name is used as the domain part in the ObjectName of MBeans when the domain is specified by the user is null.
The MBeanServer reference is internally kept. This will
allow findMBeanServer to return a reference to
this MBeanServer object.
Params:
domain – the default domain name for the created MBeanServer. This is the value that will be returned by MBeanServer.getDefaultDomain.
Throws:
SecurityException – if there is a SecurityManager and
the caller's permissions do not include or imply MBeanServerPermission("createMBeanServer").
JMRuntimeException – if the property
javax.management.builder.initial exists but the class it names cannot be instantiated through a public no-argument constructor; or if the instantiated builder returns null from its 
newMBeanServerDelegate or newMBeanServer methods.
ClassCastException – if the property
javax.management.builder.initial exists and can be instantiated but is not assignment compatible with MBeanServerBuilder.
Returns:
the newly created MBeanServer./**
     * <p>Return a new object implementing the {@link MBeanServer}
     * interface with the specified default domain name.  The given
     * domain name is used as the domain part in the ObjectName of
     * MBeans when the domain is specified by the user is null.</p>
     *
     * <p>The MBeanServer reference is internally kept. This will
     * allow <CODE>findMBeanServer</CODE> to return a reference to
     * this MBeanServer object.</p>
     *
     * @param domain the default domain name for the created
     * MBeanServer.  This is the value that will be returned by {@link
     * MBeanServer#getDefaultDomain}.
     *
     * @return the newly created MBeanServer.
     *
     * @exception SecurityException if there is a SecurityManager and
     * the caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("createMBeanServer")</code>.
     *
     * @exception JMRuntimeException if the property
     * <code>javax.management.builder.initial</code> exists but the
     * class it names cannot be instantiated through a public
     * no-argument constructor; or if the instantiated builder returns
     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate
     * newMBeanServerDelegate} or {@link
     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.
     *
     * @exception ClassCastException if the property
     * <code>javax.management.builder.initial</code> exists and can be
     * instantiated but is not assignment compatible with {@link
     * MBeanServerBuilder}.
     */
    public static MBeanServer createMBeanServer(String domain)  {
        checkPermission("createMBeanServer");

        final MBeanServer mBeanServer = newMBeanServer(domain);
        addMBeanServer(mBeanServer);
        return mBeanServer;
    }

    
Return a new object implementing the MBeanServer interface
with a standard default domain name, without keeping an
internal reference to this new object.  The default domain name
is used as the domain part in the ObjectName of MBeans when the
domain is specified by the user is null.
The standard default domain name is
DefaultDomain.
No reference is kept. findMBeanServer will not
be able to return a reference to this MBeanServer object, but
the garbage collector will be able to remove the MBeanServer
object when it is no longer referenced.
This method is equivalent to newMBeanServer(null).
Throws:
SecurityException – if there is a SecurityManager and the
caller's permissions do not include or imply MBeanServerPermission("newMBeanServer").
JMRuntimeException – if the property
javax.management.builder.initial exists but the class it names cannot be instantiated through a public no-argument constructor; or if the instantiated builder returns null from its 
newMBeanServerDelegate or newMBeanServer methods.
ClassCastException – if the property
javax.management.builder.initial exists and can be instantiated but is not assignment compatible with MBeanServerBuilder.
Returns:
the newly created MBeanServer./**
     * <p>Return a new object implementing the MBeanServer interface
     * with a standard default domain name, without keeping an
     * internal reference to this new object.  The default domain name
     * is used as the domain part in the ObjectName of MBeans when the
     * domain is specified by the user is null.</p>
     *
     * <p>The standard default domain name is
     * <code>DefaultDomain</code>.</p>
     *
     * <p>No reference is kept. <CODE>findMBeanServer</CODE> will not
     * be able to return a reference to this MBeanServer object, but
     * the garbage collector will be able to remove the MBeanServer
     * object when it is no longer referenced.</p>
     *
     * <p>This method is equivalent to <code>newMBeanServer(null)</code>.</p>
     *
     * @return the newly created MBeanServer.
     *
     * @exception SecurityException if there is a SecurityManager and the
     * caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("newMBeanServer")</code>.
     *
     * @exception JMRuntimeException if the property
     * <code>javax.management.builder.initial</code> exists but the
     * class it names cannot be instantiated through a public
     * no-argument constructor; or if the instantiated builder returns
     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate
     * newMBeanServerDelegate} or {@link
     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.
     *
     * @exception ClassCastException if the property
     * <code>javax.management.builder.initial</code> exists and can be
     * instantiated but is not assignment compatible with {@link
     * MBeanServerBuilder}.
     */
    public static MBeanServer newMBeanServer() {
        return newMBeanServer(null);
    }

    
Return a new object implementing the MBeanServer interface
with the specified default domain name, without keeping an
internal reference to this new object.  The given domain name
is used as the domain part in the ObjectName of MBeans when the
domain is specified by the user is null.
No reference is kept. findMBeanServer will not
be able to return a reference to this MBeanServer object, but
the garbage collector will be able to remove the MBeanServer
object when it is no longer referenced.
Params:
domain – the default domain name for the created MBeanServer. This is the value that will be returned by MBeanServer.getDefaultDomain.
Throws:
SecurityException – if there is a SecurityManager and the
caller's permissions do not include or imply MBeanServerPermission("newMBeanServer").
JMRuntimeException – if the property
javax.management.builder.initial exists but the class it names cannot be instantiated through a public no-argument constructor; or if the instantiated builder returns null from its 
newMBeanServerDelegate or newMBeanServer methods.
ClassCastException – if the property
javax.management.builder.initial exists and can be instantiated but is not assignment compatible with MBeanServerBuilder.
Returns:
the newly created MBeanServer./**
     * <p>Return a new object implementing the MBeanServer interface
     * with the specified default domain name, without keeping an
     * internal reference to this new object.  The given domain name
     * is used as the domain part in the ObjectName of MBeans when the
     * domain is specified by the user is null.</p>
     *
     * <p>No reference is kept. <CODE>findMBeanServer</CODE> will not
     * be able to return a reference to this MBeanServer object, but
     * the garbage collector will be able to remove the MBeanServer
     * object when it is no longer referenced.</p>
     *
     * @param domain the default domain name for the created
     * MBeanServer.  This is the value that will be returned by {@link
     * MBeanServer#getDefaultDomain}.
     *
     * @return the newly created MBeanServer.
     *
     * @exception SecurityException if there is a SecurityManager and the
     * caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("newMBeanServer")</code>.
     *
     * @exception JMRuntimeException if the property
     * <code>javax.management.builder.initial</code> exists but the
     * class it names cannot be instantiated through a public
     * no-argument constructor; or if the instantiated builder returns
     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate
     * newMBeanServerDelegate} or {@link
     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.
     *
     * @exception ClassCastException if the property
     * <code>javax.management.builder.initial</code> exists and can be
     * instantiated but is not assignment compatible with {@link
     * MBeanServerBuilder}.
     */
    public static MBeanServer newMBeanServer(String domain)  {
        checkPermission("newMBeanServer");

        // Get the builder. Creates a new one if necessary.
        //
        final MBeanServerBuilder mbsBuilder = getNewMBeanServerBuilder();
        // Returned value cannot be null.  NullPointerException if violated.

        synchronized(mbsBuilder) {
            final MBeanServerDelegate delegate  =
                    mbsBuilder.newMBeanServerDelegate();
            if (delegate == null) {
                final String msg =
                        "MBeanServerBuilder.newMBeanServerDelegate() " +
                        "returned null";
                throw new JMRuntimeException(msg);
            }
            final MBeanServer mbeanServer =
                    mbsBuilder.newMBeanServer(domain,null,delegate);
            if (mbeanServer == null) {
                final String msg =
                        "MBeanServerBuilder.newMBeanServer() returned null";
                throw new JMRuntimeException(msg);
            }
            return mbeanServer;
        }
    }

    
Return a list of registered MBeanServer objects.  A
registered MBeanServer object is one that was created by one of
the createMBeanServer methods and not subsequently
released with releaseMBeanServer.
Params:
agentId – The agent identifier of the MBeanServer to
retrieve.  If this parameter is null, all registered
MBeanServers in this JVM are returned.  Otherwise, only
MBeanServers whose id is equal to agentId are
returned.  The id of an MBeanServer is the
MBeanServerId attribute of its delegate MBean.
Throws:
SecurityException – if there is a SecurityManager and the
caller's permissions do not include or imply MBeanServerPermission("findMBeanServer").
Returns:
A list of MBeanServer objects./**
     * <p>Return a list of registered MBeanServer objects.  A
     * registered MBeanServer object is one that was created by one of
     * the <code>createMBeanServer</code> methods and not subsequently
     * released with <code>releaseMBeanServer</code>.</p>
     *
     * @param agentId The agent identifier of the MBeanServer to
     * retrieve.  If this parameter is null, all registered
     * MBeanServers in this JVM are returned.  Otherwise, only
     * MBeanServers whose id is equal to <code>agentId</code> are
     * returned.  The id of an MBeanServer is the
     * <code>MBeanServerId</code> attribute of its delegate MBean.
     *
     * @return A list of MBeanServer objects.
     *
     * @exception SecurityException if there is a SecurityManager and the
     * caller's permissions do not include or imply <code>{@link
     * MBeanServerPermission}("findMBeanServer")</code>.
     */
    public synchronized static
            ArrayList<MBeanServer> findMBeanServer(String agentId) {

        checkPermission("findMBeanServer");

        if (agentId == null)
            return new ArrayList<MBeanServer>(mBeanServerList);

        ArrayList<MBeanServer> result = new ArrayList<MBeanServer>();
        for (MBeanServer mbs : mBeanServerList) {
            String name = mBeanServerId(mbs);
            if (agentId.equals(name))
                result.add(mbs);
        }
        return result;
    }

    
Return the ClassLoaderRepository used by the given MBeanServer. This method is equivalent to server.getClassLoaderRepository(). 
Params:
server – The MBeanServer under examination. Since JMX 1.2,
if server is null, the result is a NullPointerException. This behavior differs from what was implemented in JMX 1.1 - where the possibility to use null was deprecated.
Throws:
SecurityException – if there is a SecurityManager and
the caller's permissions do not include or imply MBeanPermission("getClassLoaderRepository").
NullPointerException – if server is null.
Returns:
The Class Loader Repository used by the given MBeanServer./**
     * Return the ClassLoaderRepository used by the given MBeanServer.
     * This method is equivalent to {@link
     * MBeanServer#getClassLoaderRepository() server.getClassLoaderRepository()}.
     * @param server The MBeanServer under examination. Since JMX 1.2,
     * if <code>server</code> is <code>null</code>, the result is a
     * {@link NullPointerException}.  This behavior differs from what
     * was implemented in JMX 1.1 - where the possibility to use
     * <code>null</code> was deprecated.
     * @return The Class Loader Repository used by the given MBeanServer.
     * @exception SecurityException if there is a SecurityManager and
     * the caller's permissions do not include or imply <code>{@link
     * MBeanPermission}("getClassLoaderRepository")</code>.
     *
     * @exception NullPointerException if <code>server</code> is null.
     *
     **/
    public static ClassLoaderRepository getClassLoaderRepository(
            MBeanServer server) {
        return server.getClassLoaderRepository();
    }

    private static String mBeanServerId(MBeanServer mbs) {
        try {
            return (String) mbs.getAttribute(MBeanServerDelegate.DELEGATE_NAME,
                    "MBeanServerId");
        } catch (JMException e) {
            JmxProperties.MISC_LOGGER.finest(
                    "Ignoring exception while getting MBeanServerId: "+e);
            return null;
        }
    }

    private static void checkPermission(String action)
    throws SecurityException {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            Permission perm = new MBeanServerPermission(action);
            sm.checkPermission(perm);
        }
    }

    private static synchronized void addMBeanServer(MBeanServer mbs) {
        mBeanServerList.add(mbs);
    }

    private static synchronized void removeMBeanServer(MBeanServer mbs) {
        boolean removed = mBeanServerList.remove(mbs);
        if (!removed) {
            MBEANSERVER_LOGGER.logp(Level.FINER,
                    MBeanServerFactory.class.getName(),
                    "removeMBeanServer(MBeanServer)",
                    "MBeanServer was not in list!");
            throw new IllegalArgumentException("MBeanServer was not in list!");
        }
    }

    private static final ArrayList<MBeanServer> mBeanServerList =
            new ArrayList<MBeanServer>();

    
Load the builder class through the context class loader.
Params:
builderClassName – The name of the builder class./**
     * Load the builder class through the context class loader.
     * @param builderClassName The name of the builder class.
     **/
    private static Class<?> loadBuilderClass(String builderClassName)
    throws ClassNotFoundException {
        final ClassLoader loader =
                Thread.currentThread().getContextClassLoader();

        if (loader != null) {
            // Try with context class loader
            return loader.loadClass(builderClassName);
        }

        // No context class loader? Try with Class.forName()
        return ReflectUtil.forName(builderClassName);
    }

    
Creates the initial builder according to the
javax.management.builder.initial System property - if specified.
If any checked exception needs to be thrown, it is embedded in
a JMRuntimeException.
/**
     * Creates the initial builder according to the
     * javax.management.builder.initial System property - if specified.
     * If any checked exception needs to be thrown, it is embedded in
     * a JMRuntimeException.
     **/
    private static MBeanServerBuilder newBuilder(Class<?> builderClass) {
        try {
            final Object abuilder = builderClass.newInstance();
            return (MBeanServerBuilder)abuilder;
        } catch (RuntimeException x) {
            throw x;
        } catch (Exception x) {
            final String msg =
                    "Failed to instantiate a MBeanServerBuilder from " +
                    builderClass + ": " + x;
            throw new JMRuntimeException(msg, x);
        }
    }

    
Instantiate a new builder according to the
javax.management.builder.initial System property - if needed.
/**
     * Instantiate a new builder according to the
     * javax.management.builder.initial System property - if needed.
     **/
    private static synchronized void checkMBeanServerBuilder() {
        try {
            GetPropertyAction act =
                    new GetPropertyAction(JMX_INITIAL_BUILDER);
            String builderClassName = AccessController.doPrivileged(act);

            try {
                final Class<?> newBuilderClass;
                if (builderClassName == null || builderClassName.length() == 0)
                    newBuilderClass = MBeanServerBuilder.class;
                else
                    newBuilderClass = loadBuilderClass(builderClassName);

                // Check whether a new builder needs to be created
                if (builder != null) {
                    final Class<?> builderClass = builder.getClass();
                    if (newBuilderClass == builderClass)
                        return; // no need to create a new builder...
                }

                // Create a new builder
                builder = newBuilder(newBuilderClass);
            } catch (ClassNotFoundException x) {
                final String msg =
                        "Failed to load MBeanServerBuilder class " +
                        builderClassName + ": " + x;
                throw new JMRuntimeException(msg, x);
            }
        } catch (RuntimeException x) {
            if (MBEANSERVER_LOGGER.isLoggable(Level.FINEST)) {
                StringBuilder strb = new StringBuilder()
                .append("Failed to instantiate MBeanServerBuilder: ").append(x)
                .append("\n\t\tCheck the value of the ")
                .append(JMX_INITIAL_BUILDER).append(" property.");
                MBEANSERVER_LOGGER.logp(Level.FINEST,
                        MBeanServerFactory.class.getName(),
                        "checkMBeanServerBuilder",
                        strb.toString());
            }
            throw x;
        }
    }

    
Get the current MBeanServerBuilder, as specified by the current value of the javax.management.builder.initial property. This method consults the property and instantiates a new builder if needed. 
Throws:
SecurityException – if there is a SecurityManager and
the caller's permissions do not make it possible to instantiate
a new builder.
JMRuntimeException – if the builder instantiation fails with a checked exception - ClassNotFoundException etc...
Returns:
the new current MBeanServerBuilder./**
     * Get the current {@link javax.management.MBeanServerBuilder},
     * as specified by the current value of the
     * javax.management.builder.initial property.
     *
     * This method consults the property and instantiates a new builder
     * if needed.
     *
     * @return the new current {@link javax.management.MBeanServerBuilder}.
     *
     * @exception SecurityException if there is a SecurityManager and
     * the caller's permissions do not make it possible to instantiate
     * a new builder.
     * @exception JMRuntimeException if the builder instantiation
     *   fails with a checked exception -
     *   {@link java.lang.ClassNotFoundException} etc...
     *
     **/
    private static synchronized MBeanServerBuilder getNewMBeanServerBuilder() {
        checkMBeanServerBuilder();
        return builder;
    }

}