GarbageCollectionNotificationInfo
, GcInfo
public interface CompositeDataView
A Java class can implement this interface to indicate how it is to be converted into a CompositeData
by the MXBean framework.
A typical way to use this class is to add extra items to the CompositeData
in addition to the ones that are declared in the CompositeType
supplied by the MXBean framework. To do this, you must create another CompositeType
that has all the same items, plus your extra items.
For example, suppose you have a class Measure
that consists of a String called units
and a value
that is either a long
or a double
. It might look like this:
public class Measure implements CompositeDataView { private String units; private Number value; // a Long or a Double public Measure(String units, Number value) { this.units = units; this.value = value; } public static Measure from(CompositeData cd) { return new Measure((String) cd.get("units"), (Number) cd.get("value")); } public String getUnits() { return units; } // Can't be called getValue(), because Number is not a valid type // in an MXBean, so the implied "value" property would be rejected. public Number _getValue() { return value; } public CompositeData toCompositeData(CompositeType ct) { try {List<String> itemNames = new ArrayList<String>(ct.keySet());
List<String> itemDescriptions = new ArrayList<String>();
List<OpenType<?>> itemTypes = new ArrayList<OpenType<?>>();
for (String item : itemNames) { itemDescriptions.add(ct.getDescription(item)); itemTypes.add(ct.getType(item)); } itemNames.add("value"); itemDescriptions.add("long or double value of the measure"); itemTypes.add((value instanceof Long) ? SimpleType.LONG : SimpleType.DOUBLE); CompositeType xct = new CompositeType(ct.getTypeName(), ct.getDescription(), itemNames.toArray(new String[0]), itemDescriptions.toArray(new String[0]), itemTypes.toArray(new OpenType<?>[0])); CompositeData cd = new CompositeDataSupport(xct, new String[] {"units", "value"}, new Object[] {units, value}); assert ct.isValue(cd); // check we've done it right return cd; } catch (Exception e) { throw new RuntimeException(e); } } }
The CompositeType
that will appear in the openType
field of the Descriptor
for an attribute or operation of this type will show only the units
item, but the actual CompositeData
that is generated will have both units
and value
.
Modifier and Type | Method | Description |
---|---|---|
CompositeData |
toCompositeData |
Return a CompositeData corresponding to the values in this object. |
CompositeData toCompositeData(CompositeType ct)
Return a CompositeData
corresponding to the values in this object. The returned value should usually be an instance of CompositeDataSupport
, or a class that serializes as a CompositeDataSupport
via a writeReplace
method. Otherwise, a remote client that receives the object might not be able to reconstruct it.
ct
- The expected CompositeType
of the returned value. If the returned value is cd
, then cd.getCompositeType().equals(ct)
should be true. Typically this will be because cd
is a CompositeDataSupport
constructed with ct
as its CompositeType
.CompositeData
.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.management/javax/management/openmbean/CompositeDataView.html