Provides the definition of the ModelMBean classes. A Model
MBean is an MBean that acts as a bridge between the management
interface and the underlying managed resource. Both the
management interface and the managed resource are specified as
Java objects. The same Model MBean implementation can be
reused many times with different management interfaces and
managed resources, and it can provide common functionality
such as persistence and caching.
A Model MBean implements the ModelMBean
interface.
It is a DynamicMBean
whose getMBeanInfo
method returns an object implementing ModelMBeanInfo
.
Every MBean has an MBeanInfo
with information about the MBean itself, and its
attributes, operations, constructors, and notifications. A
Model MBean augments this MBeanInfo
with Descriptor
s that encode
additional information in the form of (key,value) pairs.
Usually, Descriptor
s are instances of DescriptorSupport
.
The class RequiredModelMBean
provides a standard Model MBean
implementation.
The following example shows a Model MBean being used to make
the get
method of a HashMap
available for management through an MBean server. No other
methods are available through the MBean server. There is
nothing special about HashMap
here. Public
methods from any public class can be exposed for management in
the same way.
import java.lang.reflect.Method;
import java.util.HashMap;
import javax.management.*;
import javax.management.modelmbean.*;
// ...
MBeanServer mbs = MBeanServerFactory.createMBeanServer();
// The MBean Server
HashMap map = new HashMap();
// The resource that will be managed
// Construct the management interface for the Model MBean
Method getMethod = HashMap.class.getMethod("get", new Class[] {Object.class});
ModelMBeanOperationInfo getInfo =
new ModelMBeanOperationInfo("Get value for key", getMethod);
ModelMBeanInfo mmbi =
new ModelMBeanInfoSupport(HashMap.class.getName(),
"Map of keys and values",
null, // no attributes
null, // no constructors
new ModelMBeanOperationInfo[] {getInfo},
null); // no notifications
// Make the Model MBean and link it to the resource
ModelMBean mmb = new RequiredModelMBean(mmbi);
mmb.setManagedResource(map, "ObjectReference");
// Register the Model MBean in the MBean Server
ObjectName mapName = new ObjectName(":type=Map,name=whatever");
mbs.registerMBean(mmb, mapName);
// Resource can evolve independently of the MBean
map.put("key", "value");
// Can access the "get" method through the MBean Server
mbs.invoke(mapName, "get", new Object[] {"key"}, new String[] {Object.class.getName()});
// returns "value"