Can be implemented by an MBean in order to * carry out operations before and after being registered or unregistered from * the MBean Server. An MBean can also implement this interface in order * to get a reference to the MBean Server and/or its name within that * MBean Server.
* *As an alternative to implementing {@code MBeanRegistration}, if all that * is needed is the MBean Server or ObjectName then an MBean can use * resource injection.
* *If a field in the MBean object has type {@link ObjectName} and has
* the {@link javax.annotation.Resource @Resource} annotation,
* then the {@code ObjectName} under which the MBean is registered is
* assigned to that field during registration. Likewise, if a field has type
* {@link MBeanServer} and the @Resource annotation, then it will
* be set to the {@code MBeanServer} in which the MBean is registered.
For example:
* *
* public Configuration implements ConfigurationMBean {
* @Resource
* private volatile MBeanServer mbeanServer;
* @Resource
* private volatile ObjectName objectName;
* ...
* void unregisterSelf() throws Exception {
* mbeanServer.unregisterMBean(objectName);
* }
* }
*
*
* Resource injection can also be used on fields of type * {@link SendNotification} to simplify notification sending. Such a field * will get a reference to an object of type {@code SendNotification} when * the MBean is registered, and it can use this reference to send notifications. * For example:
* *
* public Configuration implements ConfigurationMBean {
* @Resource
* private volatile SendNotification sender;
* ...
* private void updated() {
* Notification n = new Notification(...);
* sender.sendNotification(n);
* }
* }
*
*
* A field to be injected must not be static. It is recommended that * such fields be declared {@code volatile}.
* *It is also possible to use the @Resource annotation on
* methods. Such a method must have a {@code void} return type and a single
* argument of the appropriate type, for example {@code ObjectName}.
Any number of fields and methods may have the @Resource
* annotation. All fields and methods with type {@code ObjectName}
* (for example) will receive the same {@code ObjectName} value.
Resource injection is available for all types of MBeans, not just * Standard MBeans.
* *If an MBean implements the {@link DynamicWrapperMBean} interface then * resource injection happens on the object returned by that interface's * {@link DynamicWrapperMBean#getWrappedObject() getWrappedObject()} method * rather than on the MBean object itself. * *
Resource injection happens after the {@link #preRegister preRegister}
* method is called (if any), and before the MBean is actually registered
* in the MBean Server. If a @Resource method throws
* an exception, the effect is the same as if {@code preRegister} had
* thrown the exception. In particular it will prevent the MBean from being
* registered.
Resource injection can be used on a field or method where the type
* is a parent of the injected type, if the injected type is explicitly
* specified in the @Resource annotation. For example:
* @Resource(type = MBeanServer.class) * private volatile MBeanServerConnection mbsc; ** *
Formally, suppose R is the type in the @Resource
* annotation and T is the type of the method parameter or field.
* Then one of R and T must be a subtype of the other
* (or they must be the same type). Injection happens if this subtype
* is {@code MBeanServer}, {@code ObjectName}, or {@code SendNotification}.
* Otherwise the @Resource annotation is ignored.
Resource injection in MBeans is new in version 2.0 of the JMX API.
* * @since 1.5 */ public interface MBeanRegistration { /** * Allows the MBean to perform any operations it needs before * being registered in the MBean Server. If the name of the MBean * is not specified, the MBean can provide a name for its * registration. If any exception is raised, the MBean will not be * registered in the MBean Server. * * @param server The MBean Server in which the MBean will be registered. * * @param name The object name of the MBean. This name is null if * the name parameter to one of thecreateMBean or
* registerMBean methods in the {@link MBeanServer}
* interface is null. In that case, this method must return a
* non-null ObjectName for the new MBean.
*
* @return The name under which the MBean is to be registered.
* This value must not be null. If the name
* parameter is not null, it will usually but not necessarily be
* the returned value.
*
* @exception java.lang.Exception This exception will be caught by
* the MBean Server and re-thrown as an {@link
* MBeanRegistrationException}.
*/
public ObjectName preRegister(MBeanServer server,
ObjectName name) throws java.lang.Exception;
/**
* Allows the MBean to perform any operations needed after having been
* registered in the MBean server or after the registration has failed.
* If the implementation of this method throws a {@link RuntimeException} * or an {@link Error}, the MBean Server will rethrow those inside * a {@link RuntimeMBeanException} or {@link RuntimeErrorException}, * respectively. However, throwing an exception in {@code postRegister} * will not change the state of the MBean: * if the MBean was already registered ({@code registrationDone} is * {@code true}), the MBean will remain registered.
*This might be confusing for the code calling {@code createMBean()} * or {@code registerMBean()}, as such code might assume that MBean * registration has failed when such an exception is raised. * Therefore it is recommended that implementations of * {@code postRegister} do not throw Runtime Exceptions or Errors if it * can be avoided.
* @param registrationDone Indicates whether or not the MBean has * been successfully registered in the MBean server. The value * false means that the registration phase has failed. */ public void postRegister(Boolean registrationDone); /** * Allows the MBean to perform any operations it needs before * being unregistered by the MBean server. * * @exception java.lang.Exception This exception will be caught by * the MBean server and re-thrown as an {@link * MBeanRegistrationException}. */ public void preDeregister() throws java.lang.Exception ; /** * Allows the MBean to perform any operations needed after having been * unregistered in the MBean server. *If the implementation of this method throws a {@link RuntimeException} * or an {@link Error}, the MBean Server will rethrow those inside * a {@link RuntimeMBeanException} or {@link RuntimeErrorException}, * respectively. However, throwing an excepption in {@code postDeregister} * will not change the state of the MBean: * the MBean was already successfully deregistered and will remain so.
*This might be confusing for the code calling * {@code unregisterMBean()}, as it might assume that MBean deregistration * has failed. Therefore it is recommended that implementations of * {@code postDeregister} do not throw Runtime Exceptions or Errors if it * can be avoided.
*/ public void postDeregister(); }