https://openjdk.java.net/ 
/*
 * Copyright (c) 2002, 2007, 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 javax.management.remote;

import com.sun.jmx.mbeanserver.Util;
import java.io.IOException;
import java.net.MalformedURLException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Iterator;
import java.util.ServiceLoader;
import java.util.StringTokenizer;
import java.security.AccessController;
import java.security.PrivilegedAction;

import com.sun.jmx.remote.util.ClassLogger;
import com.sun.jmx.remote.util.EnvHelp;
import sun.reflect.misc.ReflectUtil;



Factory to create JMX API connector clients.  There
are no instances of this class.


Connections are usually made using the connect method of this class. More advanced applications can separate the creation of the connector client, using 
newJMXConnector and the establishment of the connection itself, using JMXConnector.connect(Map<String,?>).


Each client is created by an instance of JMXConnectorProvider. This instance is found as follows. Suppose the given JMXServiceURL looks like "service:jmx:protocol:remainder". Then the factory will attempt to find the appropriate JMXConnectorProvider for protocol.  Each
occurrence of the character + or - in
protocol is replaced by . or
_, respectively.


A provider package list is searched for as follows:


    

  1. If the environment parameter to newJMXConnector contains the key jmx.remote.protocol.provider.pkgs then the
associated value is the provider package list.

  2. Otherwise, if the system property
jmx.remote.protocol.provider.pkgs exists, then its value
is the provider package list.

  3. Otherwise, there is no provider package list.



The provider package list is a string that is interpreted as a
list of non-empty Java package names separated by vertical bars
(|). If the string is empty, then so is the provider package list. If the provider package list is not a String, or if it contains an element that is an empty string, a JMXProviderException is thrown.


If the provider package list exists and is not empty, then for
each element pkg of the list, the factory
will attempt to load the class


pkg.protocol.ClientProvider



If the environment parameter to newJMXConnector contains the key jmx.remote.protocol.provider.class.loader then the associated value is the class loader to use to load the provider. If the associated value is not an instance of ClassLoader, an IllegalArgumentException is thrown.


If the jmx.remote.protocol.provider.class.loader
key is not present in the environment parameter, the
calling thread's context class loader is used.


If the attempt to load this class produces a ClassNotFoundException, the search for a handler continues with the next element of the list.


Otherwise, a problem with the provider found is signalled by a JMXProviderException whose cause indicates the underlying exception, as follows:


    

  • if the attempt to load the class produces an exception other
than ClassNotFoundException, that is the
cause;

  • if Class.newInstance() for the class produces an exception, that is the cause.



If no provider is found by the above steps, including the
default case where there is no provider package list, then the
implementation will use its own provider for
protocol, or it will throw a
MalformedURLException if there is none.  An
implementation may choose to find providers by other means.  For
example, it may support the 
JAR conventions for service providers, where the service
interface is JMXConnectorProvider.


Every implementation must support the RMI connector protocols,
specified with the string rmi or
iiop.


Once a provider is found, the result of the
newJMXConnector method is the result of calling newJMXConnector on the provider.


The Map parameter passed to the
JMXConnectorProvider is a new read-only
Map that contains all the entries that were in the
environment parameter to 
JMXConnectorFactory.newJMXConnector, if there was one. Additionally, if the jmx.remote.protocol.provider.class.loader key is not
present in the environment parameter, it is added to
the new read-only Map.  The associated value is the
calling thread's context class loader.


Since:1.5
/**
 * <p>Factory to create JMX API connector clients.  There
 * are no instances of this class.</p>
 *
 * <p>Connections are usually made using the {@link
 * #connect(JMXServiceURL) connect} method of this class.  More
 * advanced applications can separate the creation of the connector
 * client, using {@link #newJMXConnector(JMXServiceURL, Map)
 * newJMXConnector} and the establishment of the connection itself, using
 * {@link JMXConnector#connect(Map)}.</p>
 *
 * <p>Each client is created by an instance of {@link
 * JMXConnectorProvider}.  This instance is found as follows.  Suppose
 * the given {@link JMXServiceURL} looks like
 * <code>"service:jmx:<em>protocol</em>:<em>remainder</em>"</code>.
 * Then the factory will attempt to find the appropriate {@link
 * JMXConnectorProvider} for <code><em>protocol</em></code>.  Each
 * occurrence of the character <code>+</code> or <code>-</code> in
 * <code><em>protocol</em></code> is replaced by <code>.</code> or
 * <code>_</code>, respectively.</p>
 *
 * <p>A <em>provider package list</em> is searched for as follows:</p>
 *
 * <ol>
 *
 * <li>If the <code>environment</code> parameter to {@link
 * #newJMXConnector(JMXServiceURL, Map) newJMXConnector} contains the
 * key <code>jmx.remote.protocol.provider.pkgs</code> then the
 * associated value is the provider package list.
 *
 * <li>Otherwise, if the system property
 * <code>jmx.remote.protocol.provider.pkgs</code> exists, then its value
 * is the provider package list.
 *
 * <li>Otherwise, there is no provider package list.
 *
 * </ol>
 *
 * <p>The provider package list is a string that is interpreted as a
 * list of non-empty Java package names separated by vertical bars
 * (<code>|</code>).  If the string is empty, then so is the provider
 * package list.  If the provider package list is not a String, or if
 * it contains an element that is an empty string, a {@link
 * JMXProviderException} is thrown.</p>
 *
 * <p>If the provider package list exists and is not empty, then for
 * each element <code><em>pkg</em></code> of the list, the factory
 * will attempt to load the class
 *
 * <blockquote>
 * <code><em>pkg</em>.<em>protocol</em>.ClientProvider</code>
 * </blockquote>

 * <p>If the <code>environment</code> parameter to {@link
 * #newJMXConnector(JMXServiceURL, Map) newJMXConnector} contains the
 * key <code>jmx.remote.protocol.provider.class.loader</code> then the
 * associated value is the class loader to use to load the provider.
 * If the associated value is not an instance of {@link
 * java.lang.ClassLoader}, an {@link
 * java.lang.IllegalArgumentException} is thrown.</p>
 *
 * <p>If the <code>jmx.remote.protocol.provider.class.loader</code>
 * key is not present in the <code>environment</code> parameter, the
 * calling thread's context class loader is used.</p>
 *
 * <p>If the attempt to load this class produces a {@link
 * ClassNotFoundException}, the search for a handler continues with
 * the next element of the list.</p>
 *
 * <p>Otherwise, a problem with the provider found is signalled by a
 * {@link JMXProviderException} whose {@link
 * JMXProviderException#getCause() <em>cause</em>} indicates the underlying
 * exception, as follows:</p>
 *
 * <ul>
 *
 * <li>if the attempt to load the class produces an exception other
 * than <code>ClassNotFoundException</code>, that is the
 * <em>cause</em>;
 *
 * <li>if {@link Class#newInstance()} for the class produces an
 * exception, that is the <em>cause</em>.
 *
 * </ul>
 *
 * <p>If no provider is found by the above steps, including the
 * default case where there is no provider package list, then the
 * implementation will use its own provider for
 * <code><em>protocol</em></code>, or it will throw a
 * <code>MalformedURLException</code> if there is none.  An
 * implementation may choose to find providers by other means.  For
 * example, it may support the <a
 * href="{@docRoot}/../technotes/guides/jar/jar.html#Service Provider">
 * JAR conventions for service providers</a>, where the service
 * interface is <code>JMXConnectorProvider</code>.</p>
 *
 * <p>Every implementation must support the RMI connector protocols,
 * specified with the string <code>rmi</code> or
 * <code>iiop</code>.</p>
 *
 * <p>Once a provider is found, the result of the
 * <code>newJMXConnector</code> method is the result of calling {@link
 * JMXConnectorProvider#newJMXConnector(JMXServiceURL,Map) newJMXConnector}
 * on the provider.</p>
 *
 * <p>The <code>Map</code> parameter passed to the
 * <code>JMXConnectorProvider</code> is a new read-only
 * <code>Map</code> that contains all the entries that were in the
 * <code>environment</code> parameter to {@link
 * #newJMXConnector(JMXServiceURL,Map)
 * JMXConnectorFactory.newJMXConnector}, if there was one.
 * Additionally, if the
 * <code>jmx.remote.protocol.provider.class.loader</code> key is not
 * present in the <code>environment</code> parameter, it is added to
 * the new read-only <code>Map</code>.  The associated value is the
 * calling thread's context class loader.</p>
 *
 * @since 1.5
 */
public class JMXConnectorFactory {

    
Name of the attribute that specifies the default class
loader. This class loader is used to deserialize return values and
exceptions from remote MBeanServerConnection calls. The value associated with this attribute is an instance of ClassLoader.


/**
     * <p>Name of the attribute that specifies the default class
     * loader. This class loader is used to deserialize return values and
     * exceptions from remote <code>MBeanServerConnection</code>
     * calls.  The value associated with this attribute is an instance
     * of {@link ClassLoader}.</p>
     */
    public static final String DEFAULT_CLASS_LOADER =
        "jmx.remote.default.class.loader";

    
Name of the attribute that specifies the provider packages
that are consulted when looking for the handler for a protocol.
The value associated with this attribute is a string with
package names separated by vertical bars (|).


/**
     * <p>Name of the attribute that specifies the provider packages
     * that are consulted when looking for the handler for a protocol.
     * The value associated with this attribute is a string with
     * package names separated by vertical bars (<code>|</code>).</p>
     */
    public static final String PROTOCOL_PROVIDER_PACKAGES =
        "jmx.remote.protocol.provider.pkgs";

    
Name of the attribute that specifies the class loader for loading protocol providers. The value associated with this attribute is an instance of ClassLoader.


/**
     * <p>Name of the attribute that specifies the class
     * loader for loading protocol providers.
     * The value associated with this attribute is an instance
     * of {@link ClassLoader}.</p>
     */
    public static final String PROTOCOL_PROVIDER_CLASS_LOADER =
        "jmx.remote.protocol.provider.class.loader";

    private static final String PROTOCOL_PROVIDER_DEFAULT_PACKAGE =
        "com.sun.jmx.remote.protocol";

    private static final ClassLogger logger =
        new ClassLogger("javax.management.remote.misc", "JMXConnectorFactory");

    
There are no instances of this class.  
/** There are no instances of this class.  */
    private JMXConnectorFactory() {
    }

    
Creates a connection to the connector server at the given
address.


This method is equivalent to connect(serviceURL, null).


Params:
  • serviceURL – the address of the connector server to
connect to.
Throws:
Returns:a JMXConnector whose connect method has been called.
/**
     * <p>Creates a connection to the connector server at the given
     * address.</p>
     *
     * <p>This method is equivalent to {@link
     * #connect(JMXServiceURL,Map) connect(serviceURL, null)}.</p>
     *
     * @param serviceURL the address of the connector server to
     * connect to.
     *
     * @return a <code>JMXConnector</code> whose {@link
     * JMXConnector#connect connect} method has been called.
     *
     * @exception NullPointerException if <code>serviceURL</code> is null.
     *
     * @exception IOException if the connector client or the
     * connection cannot be made because of a communication problem.
     *
     * @exception SecurityException if the connection cannot be made
     * for security reasons.
     */
    public static JMXConnector connect(JMXServiceURL serviceURL)
            throws IOException {
        return connect(serviceURL, null);
    }

    
Creates a connection to the connector server at the given
address.


This method is equivalent to:


JMXConnector conn = JMXConnectorFactory.newJMXConnector(serviceURL,
                                                        environment);
conn.connect(environment);



Params:
  • serviceURL – the address of the connector server to connect to.
  • environment – a set of attributes to determine how the
connection is made.  This parameter can be null.  Keys in this
map must be Strings.  The appropriate type of each associated
value depends on the attribute.  The contents of
environment are not changed by this call.
Throws:
Returns:a JMXConnector representing the newly-made
connection.  Each successful call to this method produces a
different object.
/**
     * <p>Creates a connection to the connector server at the given
     * address.</p>
     *
     * <p>This method is equivalent to:</p>
     *
     * <pre>
     * JMXConnector conn = JMXConnectorFactory.newJMXConnector(serviceURL,
     *                                                         environment);
     * conn.connect(environment);
     * </pre>
     *
     * @param serviceURL the address of the connector server to connect to.
     *
     * @param environment a set of attributes to determine how the
     * connection is made.  This parameter can be null.  Keys in this
     * map must be Strings.  The appropriate type of each associated
     * value depends on the attribute.  The contents of
     * <code>environment</code> are not changed by this call.
     *
     * @return a <code>JMXConnector</code> representing the newly-made
     * connection.  Each successful call to this method produces a
     * different object.
     *
     * @exception NullPointerException if <code>serviceURL</code> is null.
     *
     * @exception IOException if the connector client or the
     * connection cannot be made because of a communication problem.
     *
     * @exception SecurityException if the connection cannot be made
     * for security reasons.
     */
    public static JMXConnector connect(JMXServiceURL serviceURL,
                                       Map<String,?> environment)
            throws IOException {
        if (serviceURL == null)
            throw new NullPointerException("Null JMXServiceURL");
        JMXConnector conn = newJMXConnector(serviceURL, environment);
        conn.connect(environment);
        return conn;
    }

    
Creates a connector client for the connector server at the given address. The resultant client is not connected until its connect method is called.


Params:
  • serviceURL – the address of the connector server to connect to.
  • environment – a set of attributes to determine how the
connection is made.  This parameter can be null.  Keys in this
map must be Strings.  The appropriate type of each associated
value depends on the attribute.  The contents of
environment are not changed by this call.
Throws:
Returns:a JMXConnector representing the new
connector client.  Each successful call to this method produces
a different object.
/**
     * <p>Creates a connector client for the connector server at the
     * given address.  The resultant client is not connected until its
     * {@link JMXConnector#connect(Map) connect} method is called.</p>
     *
     * @param serviceURL the address of the connector server to connect to.
     *
     * @param environment a set of attributes to determine how the
     * connection is made.  This parameter can be null.  Keys in this
     * map must be Strings.  The appropriate type of each associated
     * value depends on the attribute.  The contents of
     * <code>environment</code> are not changed by this call.
     *
     * @return a <code>JMXConnector</code> representing the new
     * connector client.  Each successful call to this method produces
     * a different object.
     *
     * @exception NullPointerException if <code>serviceURL</code> is null.
     *
     * @exception IOException if the connector client cannot be made
     * because of a communication problem.
     *
     * @exception MalformedURLException if there is no provider for the
     * protocol in <code>serviceURL</code>.
     *
     * @exception JMXProviderException if there is a provider for the
     * protocol in <code>serviceURL</code> but it cannot be used for
     * some reason.
     */
    public static JMXConnector newJMXConnector(JMXServiceURL serviceURL,
                                               Map<String,?> environment)
            throws IOException {
        Map<String, Object> envcopy;
        if (environment == null)
            envcopy = new HashMap<String, Object>();
        else {
            EnvHelp.checkAttributes(environment);
            envcopy = new HashMap<String, Object>(environment);
        }

        final ClassLoader loader = resolveClassLoader(envcopy);
        final Class<JMXConnectorProvider> targetInterface = JMXConnectorProvider.class;
        final String protocol = serviceURL.getProtocol();
        final String providerClassName = "ClientProvider";

        JMXConnectorProvider provider =
            getProvider(serviceURL, envcopy, providerClassName,
                        targetInterface, loader);

        IOException exception = null;
        if (provider == null) {
            // Loader is null when context class loader is set to null
            // and no loader has been provided in map.
            // com.sun.jmx.remote.util.Service class extracted from j2se
            // provider search algorithm doesn't handle well null classloader.
            if (loader != null) {
                try {
                    JMXConnector connection =
                        getConnectorAsService(loader, serviceURL, envcopy);
                    if (connection != null)
                        return connection;
                } catch (JMXProviderException e) {
                    throw e;
                } catch (IOException e) {
                    exception = e;
                }
            }
            provider =
                getProvider(protocol, PROTOCOL_PROVIDER_DEFAULT_PACKAGE,
                            JMXConnectorFactory.class.getClassLoader(),
                            providerClassName, targetInterface);
        }

        if (provider == null) {
            MalformedURLException e =
                new MalformedURLException("Unsupported protocol: " + protocol);
            if (exception == null) {
                throw e;
            } else {
                throw EnvHelp.initCause(e, exception);
            }
        }

        envcopy = Collections.unmodifiableMap(envcopy);

        return provider.newJMXConnector(serviceURL, envcopy);
    }

    private static String resolvePkgs(Map env) throws JMXProviderException {

        Object pkgsObject = null;

        if (env != null)
            pkgsObject = env.get(PROTOCOL_PROVIDER_PACKAGES);

        if (pkgsObject == null)
            pkgsObject =
                AccessController.doPrivileged(new PrivilegedAction<Object>() {
                    public Object run() {
                        return System.getProperty(PROTOCOL_PROVIDER_PACKAGES);
                    }
                });

        if (pkgsObject == null)
            return null;

        if (!(pkgsObject instanceof String)) {
            final String msg = "Value of " + PROTOCOL_PROVIDER_PACKAGES +
                " parameter is not a String: " +
                pkgsObject.getClass().getName();
            throw new JMXProviderException(msg);
        }

        final String pkgs = (String) pkgsObject;
        if (pkgs.trim().equals(""))
            return null;

        // pkgs may not contain an empty element
        if (pkgs.startsWith("|") || pkgs.endsWith("|") ||
            pkgs.indexOf("||") >= 0) {
            final String msg = "Value of " + PROTOCOL_PROVIDER_PACKAGES +
                " contains an empty element: " + pkgs;
            throw new JMXProviderException(msg);
        }

        return pkgs;
    }

    static <T> T getProvider(JMXServiceURL serviceURL,
                             final Map<String, Object> environment,
                             String providerClassName,
                             Class<T> targetInterface,
                             final ClassLoader loader)
            throws IOException {

        final String protocol = serviceURL.getProtocol();

        final String pkgs = resolvePkgs(environment);

        T instance = null;

        if (pkgs != null) {
            instance =
                getProvider(protocol, pkgs, loader, providerClassName,
                            targetInterface);

            if (instance != null) {
                boolean needsWrap = (loader != instance.getClass().getClassLoader());
                environment.put(PROTOCOL_PROVIDER_CLASS_LOADER, needsWrap ? wrap(loader) : loader);
            }
        }

        return instance;
    }

    static <T> Iterator<T> getProviderIterator(final Class<T> providerClass,
                                               final ClassLoader loader) {
       ServiceLoader<T> serviceLoader =
                ServiceLoader.load(providerClass,
                loader);
       return serviceLoader.iterator();
    }

    private static ClassLoader wrap(final ClassLoader parent) {
        return parent != null ? AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
            public ClassLoader run() {
                return new ClassLoader(parent) {
                    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
                        ReflectUtil.checkPackageAccess(name);
                        return super.loadClass(name, resolve);
                    }
                };
            }
        }) : null;
    }

    private static JMXConnector getConnectorAsService(ClassLoader loader,
                                                      JMXServiceURL url,
                                                      Map<String, ?> map)
        throws IOException {

        Iterator<JMXConnectorProvider> providers =
                getProviderIterator(JMXConnectorProvider.class, loader);
        JMXConnector connection = null;
        IOException exception = null;
        while(providers.hasNext()) {
            try {
                connection = providers.next().newJMXConnector(url, map);
                return connection;
            } catch (JMXProviderException e) {
                throw e;
            } catch (Exception e) {
                if (logger.traceOn())
                    logger.trace("getConnectorAsService",
                                 "URL[" + url +
                                 "] Service provider exception: " + e);
                if (!(e instanceof MalformedURLException)) {
                    if (exception == null) {
                        if (exception instanceof IOException) {
                            exception = (IOException) e;
                        } else {
                            exception = EnvHelp.initCause(
                                new IOException(e.getMessage()), e);
                        }
                    }
                }
                continue;
            }
        }
        if (exception == null)
            return null;
        else
            throw exception;
    }

    static <T> T getProvider(String protocol,
                              String pkgs,
                              ClassLoader loader,
                              String providerClassName,
                              Class<T> targetInterface)
            throws IOException {

        StringTokenizer tokenizer = new StringTokenizer(pkgs, "|");

        while (tokenizer.hasMoreTokens()) {
            String pkg = tokenizer.nextToken();
            String className = (pkg + "." + protocol2package(protocol) +
                                "." + providerClassName);
            Class<?> providerClass;
            try {
                providerClass = Class.forName(className, true, loader);
            } catch (ClassNotFoundException e) {
                //Add trace.
                continue;
            }

            if (!targetInterface.isAssignableFrom(providerClass)) {
                final String msg =
                    "Provider class does not implement " +
                    targetInterface.getName() + ": " +
                    providerClass.getName();
                throw new JMXProviderException(msg);
            }

            // We have just proved that this cast is correct
            Class<? extends T> providerClassT = Util.cast(providerClass);
            try {
                return providerClassT.newInstance();
            } catch (Exception e) {
                final String msg =
                    "Exception when instantiating provider [" + className +
                    "]";
                throw new JMXProviderException(msg, e);
            }
        }

        return null;
    }

    static ClassLoader resolveClassLoader(Map environment) {
        ClassLoader loader = null;

        if (environment != null) {
            try {
                loader = (ClassLoader)
                    environment.get(PROTOCOL_PROVIDER_CLASS_LOADER);
            } catch (ClassCastException e) {
                final String msg =
                    "The ClassLoader supplied in the environment map using " +
                    "the " + PROTOCOL_PROVIDER_CLASS_LOADER +
                    " attribute is not an instance of java.lang.ClassLoader";
                throw new IllegalArgumentException(msg);
            }
        }

        if (loader == null) {
            loader = Thread.currentThread().getContextClassLoader();
        }

        return loader;
    }

    private static String protocol2package(String protocol) {
        return protocol.replace('+', '.').replace('-', '_');
    }
}