Commodity class to create a JMX loopback connection

JMXLoopback.java

import javax.management.MBeanServer;
import javax.management.MBeanServerConnection;
import javax.management.remote.*;
import java.io.IOException;
import java.lang.management.ManagementFactory;

/**
 * Utilitarian/commodity class to allow easy JMX testing by setting up a loopback connection
 * by wrapping the logic of a {@link JMXConnectorServer}.
 * <p/>
 * <p><b>DISCLAIMER :</b> this class is not self managed, you must ensure in your
 * code that you close things yourself. And this class is NOT thread-safe.</p>
 * <p/>
 * <p>
 * Example use of this class :
 * <pre>
 * &#x40;Before
 * public start_loopback() {
 *     jmxLoopback = new JMXLoopback(someMBeanServer);
 * }
 *
 * &#x40;After
 * public stop_loopback() {
 *     jmxLoopback.stop();
 * }
 *
 * &#x40;Test
 * public void that_definately_should_work_this_way() throws Exception {
 *     JMXConnector jmxConnetor = JMXConnectorFactory.connect(jmxLoopback.getActualJMXServiceUrl());
 *     MBeanServerConnection connection = jmx.getgetMBeanServerConnection();
 *
 *     // and so on...
 * }
 *     </pre>
 * </p>
 *
 * @see JMXConnectorServer
 * @see JMXConnectorServerFactory
 *
 * @author Brice Dutheil
 */
public class JMXLoopback {

    private static JMXConnectorServer connectorServer;
    private MBeanServer mBeanServer;
    private JMXConnector connector;

    /**
     * Creates the JMX loopback using the platform MBean server and start it.
     *
     * @throws IOException Thrown if the JMXConnectorServer cannot be created or started.
     * @see java.lang.management.ManagementFactory#getPlatformMBeanServer()
     * @see #JMXLoopback(javax.management.MBeanServer)
     */
    public JMXLoopback() throws IOException {
        this(ManagementFactory.getPlatformMBeanServer());
    }

    /**
     * Creates the JMX loopback using the given MBean server and start it.
     *
     * @param mBeanServer The MBeanServer used to create the loopback
     * @throws IOException Thrown if the JMXConnectorServer cannot be created or started.
     */
    public JMXLoopback(MBeanServer mBeanServer) throws IOException {
        this.mBeanServer = mBeanServer;

        init(mBeanServer);
    }

    private void init(MBeanServer mBeanServer) throws IOException {
        connectorServer = JMXConnectorServerFactory.newJMXConnectorServer(
                new JMXServiceURL("service:jmx:rmi://"),
                null,
                mBeanServer
        );

        connectorServer.start();
    }

    /**
     * Stop the loopback.
     *
     * @throws IOException Thrown if the JMXConnectorServer could not be stopped cleanly.
     */
    public void terminate() throws IOException {
        if (connector != null) {
            connector.close();
        }
        connectorServer.stop();
    }

    /**
     * Return the actual JMX service URL that should be used when creating your JMXConnector.
     *
     * @return The actual JMX service URL
     * @see javax.management.remote.JMXConnector
     * @see javax.management.remote.JMXConnectorFactory
     */
    public JMXServiceURL getActualJMXServiceUrl() {
        return connectorServer.getAddress();
    }


    /**
     * Commodity method to get the actual MBean server of ths loopback.
     *
     * @return The actual MBeanServer
     */
    public MBeanServer getActualMBeanServer() {
        return connectorServer.getMBeanServer();
    }

    /**
     * Create a new MBeanServerConnection using the loopback.
     *
     * <p>
     *     This creates internally a new JMXConnector. If a connection was already created,
     *     this closes the current connector and creates a new one. This connector will be
     *     closed when calling {@link #terminate()}.
     * </p>
     *
     * @return A new MBeanServerConnection
     * @throws IOException Thrown if there is a problem when connecting or creation the connection.
     */
    public MBeanServerConnection createMBeanServerConnection() throws IOException {
        if (connector != null) {
            connector.close();
            connector = null;
        }
        connector = JMXConnectorFactory.connect(connectorServer.getAddress());
        return connector.getMBeanServerConnection();
    }
}