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MBeanServerInvocationHandler.javaAPI DocJava SE 6 API18974Tue Jun 10 00:26:14 BST 2008javax.management

MBeanServerInvocationHandler

public class MBeanServerInvocationHandler extends Object implements InvocationHandler

{@link InvocationHandler} that forwards methods in an MBean's management interface through the MBean server to the MBean.

Given an {@link MBeanServerConnection}, the {@link ObjectName} of an MBean within that MBean server, and a Java interface Intf that describes the management interface of the MBean using the patterns for a Standard MBean or an MXBean, this class can be used to construct a proxy for the MBean. The proxy implements the interface Intf such that all of its methods are forwarded through the MBean server to the MBean.

If the {@code InvocationHandler} is for an MXBean, then the parameters of a method are converted from the type declared in the MXBean interface into the corresponding mapped type, and the return value is converted from the mapped type into the declared type. For example, with the method
{@code public List reverse(List list);}
and given that the mapped type for {@code List} is {@code String[]}, a call to {@code proxy.reverse(someList)} will convert {@code someList} from a {@code List} to a {@code String[]}, call the MBean operation {@code reverse}, then convert the returned {@code String[]} into a {@code List}.

The method Object.toString(), Object.hashCode(), or Object.equals(Object), when invoked on a proxy using this invocation handler, is forwarded to the MBean server as a method on the proxied MBean only if it appears in one of the proxy's interfaces. For a proxy created with {@link JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class) JMX.newMBeanProxy} or {@link JMX#newMXBeanProxy(MBeanServerConnection, ObjectName, Class) JMX.newMXBeanProxy}, this means that the method must appear in the Standard MBean or MXBean interface. Otherwise these methods have the following behavior:

  • toString() returns a string representation of the proxy
  • hashCode() returns a hash code for the proxy such that two equal proxies have the same hash code
  • equals(Object) returns true if and only if the Object argument is of the same proxy class as this proxy, with an MBeanServerInvocationHandler that has the same MBeanServerConnection and ObjectName; if one of the {@code MBeanServerInvocationHandler}s was constructed with a {@code Class} argument then the other must have been constructed with the same {@code Class} for {@code equals} to return true.
since
1.5
since.unbundled
JMX 1.2

Fields Summary
private static final WeakHashMap
mxbeanProxies
private final MBeanServerConnection
connection
private final ObjectName
objectName
private final boolean
isMXBean
Constructors Summary
public MBeanServerInvocationHandler(MBeanServerConnection connection, ObjectName objectName)

Invocation handler that forwards methods through an MBean server to a Standard MBean. This constructor may be called instead of relying on {@link JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class) JMX.newMBeanProxy}, for instance if you need to supply a different {@link ClassLoader} to {@link Proxy#newProxyInstance Proxy.newProxyInstance}.

This constructor is not appropriate for an MXBean. Use {@link #MBeanServerInvocationHandler(MBeanServerConnection, ObjectName, boolean)} for that. This constructor is equivalent to {@code new MBeanServerInvocationHandler(connection, objectName, false)}.

param
connection the MBean server connection through which all methods of a proxy using this handler will be forwarded.
param
objectName the name of the MBean within the MBean server to which methods will be forwarded.


	this(connection, objectName, false);
public MBeanServerInvocationHandler(MBeanServerConnection connection, ObjectName objectName, boolean isMXBean)

Invocation handler that can forward methods through an MBean server to a Standard MBean or MXBean. This constructor may be called instead of relying on {@link JMX#newMXBeanProxy(MBeanServerConnection, ObjectName, Class) JMX.newMXBeanProxy}, for instance if you need to supply a different {@link ClassLoader} to {@link Proxy#newProxyInstance Proxy.newProxyInstance}.

param
connection the MBean server connection through which all methods of a proxy using this handler will be forwarded.
param
objectName the name of the MBean within the MBean server to which methods will be forwarded.
param
isMXBean if true, the proxy is for an {@link MXBean}, and appropriate mappings will be applied to method parameters and return values.
since
1.6

	if (connection == null) {
	    throw new IllegalArgumentException("Null connection");
	}
	if (objectName == null) {
	    throw new IllegalArgumentException("Null object name");
	}
	this.connection = connection;
	this.objectName = objectName;
        this.isMXBean = isMXBean;
Methods Summary
private java.lang.ObjectdoLocally(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args)

        final String methodName = method.getName();

        if (methodName.equals("equals")) {
            
            if (this == args[0]) {
                return true;
            }
            
            if (!(args[0] instanceof Proxy)) {
                return false;
            }
            
            final InvocationHandler ihandler =
                Proxy.getInvocationHandler(args[0]);
            
            if (ihandler == null ||
                !(ihandler instanceof MBeanServerInvocationHandler)) {
                return false;
            }
            
            final MBeanServerInvocationHandler handler =
                (MBeanServerInvocationHandler)ihandler;

            return connection.equals(handler.connection) &&
                objectName.equals(handler.objectName) &&
                proxy.getClass().equals(args[0].getClass());
        } else if (methodName.equals("toString")) {
            return (isMXBean ? "MX" : "M") + "BeanProxy(" +
		connection + "[" + objectName + "])";
        } else if (methodName.equals("hashCode")) {
            return objectName.hashCode()+connection.hashCode();
        }

	throw new RuntimeException("Unexpected method name: " + methodName);
private static com.sun.jmx.mbeanserver.MXBeanProxyfindMXBeanProxy(java.lang.Class mxbeanInterface)

        synchronized (mxbeanProxies) {
            WeakReference<MXBeanProxy> proxyRef =
                    mxbeanProxies.get(mxbeanInterface);
            MXBeanProxy p = (proxyRef == null) ? null : proxyRef.get();
            if (p == null) {
                p = new MXBeanProxy(mxbeanInterface);
                mxbeanProxies.put(mxbeanInterface,
                                  new WeakReference<MXBeanProxy>(p));
            }
            return p;
        }
public javax.management.MBeanServerConnectiongetMBeanServerConnection()

The MBean server connection through which the methods of a proxy using this handler are forwarded.

return
the MBean server connection.
since
1.6

        return connection;
public javax.management.ObjectNamegetObjectName()

The name of the MBean within the MBean server to which methods are forwarded.

return
the object name.
since
1.6

        return objectName;
public java.lang.Objectinvoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args)

        final Class methodClass = method.getDeclaringClass();

        if (methodClass.equals(NotificationBroadcaster.class)
            || methodClass.equals(NotificationEmitter.class))
            return invokeBroadcasterMethod(proxy, method, args);

        // local or not: equals, toString, hashCode
	if (shouldDoLocally(proxy, method))
            return doLocally(proxy, method, args);
        
        try {
            if (isMXBean) {
                MXBeanProxy p = findMXBeanProxy(methodClass);
                return p.invoke(connection, objectName, method, args);
            } else {
                final String methodName = method.getName();
                final Class[] paramTypes = method.getParameterTypes();
                final Class returnType = method.getReturnType();

                /* Inexplicably, InvocationHandler specifies that args is null
                   when the method takes no arguments rather than a
                   zero-length array.  */
                final int nargs = (args == null) ? 0 : args.length;

                if (methodName.startsWith("get")
                    && methodName.length() > 3
                    && nargs == 0
                    && !returnType.equals(Void.TYPE)) {
                    return connection.getAttribute(objectName,
                        methodName.substring(3));
                }

                if (methodName.startsWith("is")
                    && methodName.length() > 2
                    && nargs == 0
                    && (returnType.equals(Boolean.TYPE)
                    || returnType.equals(Boolean.class))) {
                    return connection.getAttribute(objectName,
                        methodName.substring(2));
                }

                if (methodName.startsWith("set")
                    && methodName.length() > 3
                    && nargs == 1
                    && returnType.equals(Void.TYPE)) {
                    Attribute attr = new Attribute(methodName.substring(3), args[0]);
                    connection.setAttribute(objectName, attr);
                    return null;
                }

                final String[] signature = new String[paramTypes.length];
                for (int i = 0; i < paramTypes.length; i++)
                    signature[i] = paramTypes[i].getName();
                return connection.invoke(objectName, methodName,
                                         args, signature);
            }
        } catch (MBeanException e) {
            throw e.getTargetException();
        } catch (RuntimeMBeanException re) {
            throw re.getTargetException();
        } catch (RuntimeErrorException rre) {
            throw rre.getTargetError();
        }
        /* The invoke may fail because it can't get to the MBean, with
           one of the these exceptions declared by
           MBeanServerConnection.invoke:
           - RemoteException: can't talk to MBeanServer;
           - InstanceNotFoundException: objectName is not registered;
           - ReflectionException: objectName is registered but does not
             have the method being invoked.
           In all of these cases, the exception will be wrapped by the
           proxy mechanism in an UndeclaredThrowableException unless
           it happens to be declared in the "throws" clause of the
           method being invoked on the proxy.
         */
private java.lang.ObjectinvokeBroadcasterMethod(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args)


         
                                               
        final String methodName = method.getName();
        final int nargs = (args == null) ? 0 : args.length;

        if (methodName.equals("addNotificationListener")) {
            /* The various throws of IllegalArgumentException here
               should not happen, since we know what the methods in
               NotificationBroadcaster and NotificationEmitter
               are.  */
            if (nargs != 3) {
                final String msg =
                    "Bad arg count to addNotificationListener: " + nargs;
                throw new IllegalArgumentException(msg);
            }
            /* Other inconsistencies will produce ClassCastException
               below.  */

            NotificationListener listener = (NotificationListener) args[0];
            NotificationFilter filter = (NotificationFilter) args[1];
            Object handback = args[2];
            connection.addNotificationListener(objectName,
                                               listener,
                                               filter,
                                               handback);
            return null;

        } else if (methodName.equals("removeNotificationListener")) {

            /* NullPointerException if method with no args, but that
               shouldn't happen because removeNL does have args.  */
            NotificationListener listener = (NotificationListener) args[0];

            switch (nargs) {
            case 1:
                connection.removeNotificationListener(objectName, listener);
                return null;

            case 3:
                NotificationFilter filter = (NotificationFilter) args[1];
                Object handback = args[2];
                connection.removeNotificationListener(objectName,
                                                      listener,
                                                      filter,
                                                      handback);
                return null;

            default:
                final String msg =
                    "Bad arg count to removeNotificationListener: " + nargs;
                throw new IllegalArgumentException(msg);
            }

        } else if (methodName.equals("getNotificationInfo")) {

            if (args != null) {
                throw new IllegalArgumentException("getNotificationInfo has " +
                                                   "args");
            }

            MBeanInfo info = connection.getMBeanInfo(objectName);
            return info.getNotifications();

        } else {
            throw new IllegalArgumentException("Bad method name: " +
                                               methodName);
        }
private static booleanisLocal(java.lang.Object proxy, java.lang.reflect.Method method)

        final Class[] interfaces = proxy.getClass().getInterfaces();
        if(interfaces == null) {
            return true;
        }

	final String methodName = method.getName();
	final Class[] params = method.getParameterTypes();
	for (Class intf : interfaces) {
            try {
                intf.getMethod(methodName, params);
                return false; // found method in one of our interfaces
            } catch (NoSuchMethodException nsme) {
                // OK.
            }
        }

        return true;  // did not find in any interface
public booleanisMXBean()

If true, the proxy is for an MXBean, and appropriate mappings are applied to method parameters and return values.

return
whether the proxy is for an MXBean.
since
1.6

        return isMXBean;
public static TnewProxyInstance(javax.management.MBeanServerConnection connection, javax.management.ObjectName objectName, java.lang.Class interfaceClass, boolean notificationBroadcaster)

Return a proxy that implements the given interface by forwarding its methods through the given MBean server to the named MBean. As of 1.6, the methods {@link JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class)} and {@link JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class, boolean)} are preferred to this method.

This method is equivalent to {@link Proxy#newProxyInstance Proxy.newProxyInstance}(interfaceClass.getClassLoader(), interfaces, handler). Here handler is the result of {@link #MBeanServerInvocationHandler new MBeanServerInvocationHandler(connection, objectName)}, and interfaces is an array that has one element if notificationBroadcaster is false and two if it is true. The first element of interfaces is interfaceClass and the second, if present, is NotificationEmitter.class.

param
connection the MBean server to forward to.
param
objectName the name of the MBean within connection to forward to.
param
interfaceClass the management interface that the MBean exports, which will also be implemented by the returned proxy.
param
notificationBroadcaster make the returned proxy implement {@link NotificationEmitter} by forwarding its methods via connection. A call to {@link NotificationBroadcaster#addNotificationListener} on the proxy will result in a call to {@link MBeanServerConnection#addNotificationListener(ObjectName, NotificationListener, NotificationFilter, Object)}, and likewise for the other methods of {@link NotificationBroadcaster} and {@link NotificationEmitter}.
param
allows the compiler to know that if the {@code interfaceClass} parameter is {@code MyMBean.class}, for example, then the return type is {@code MyMBean}.
return
the new proxy instance.
see
JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class)

	final InvocationHandler handler =
	    new MBeanServerInvocationHandler(connection, objectName);
	final Class[] interfaces;
	if (notificationBroadcaster) {
	    interfaces =
		new Class[] {interfaceClass, NotificationEmitter.class};
	} else
	    interfaces = new Class[] {interfaceClass};

	Object proxy =
	    Proxy.newProxyInstance(interfaceClass.getClassLoader(),
				   interfaces,
				   handler);
	return interfaceClass.cast(proxy);
private booleanshouldDoLocally(java.lang.Object proxy, java.lang.reflect.Method method)

	final String methodName = method.getName();
	if ((methodName.equals("hashCode") || methodName.equals("toString"))
	    && method.getParameterTypes().length == 0
	    && isLocal(proxy, method))
	    return true;
	if (methodName.equals("equals")
	    && Arrays.equals(method.getParameterTypes(),
			     new Class[] {Object.class})
	    && isLocal(proxy, method))
	    return true;
	return false;