public interface Descriptor extends Serializable, Cloneable
Field names are not case-sensitive. The names
DESCRIPTORTYPE are all equivalent.
However, the case that was used when the field was first set is preserved
in the result of the
Not all field names and values are predefined. New fields can be defined and added by any program.
A descriptor can be mutable or immutable.
An immutable descriptor, once created, never changes.
Descriptor methods that could modify the contents
of the descriptor will throw an exception
for an immutable descriptor. Immutable descriptors are usually
ImmutableDescriptor or a subclass. Mutable
descriptors are usually instances of
DescriptorSupport or a subclass.
Certain fields are used by the JMX implementation. This means
either that the presence of the field may change the behavior of
the JMX API or that the field may be set in descriptors returned by
the JMX API. These fields appear in italics in the table
below, and each one has a corresponding constant in the
class. For example, the field
defaultValue is represented
by the constant
Certain other fields have conventional meanings described in the table below but they are not required to be understood or set by the JMX implementation.
Field names defined by the JMX specification in this and all
future versions will never contain a period (.). Users can safely
create their own fields by including a period in the name and be
sure that these names will not collide with any future version of
the JMX API. It is recommended to follow the Java package naming
convention to avoid collisions between field names from different
origins. For example, a field created by
have the name
Note that the values in the
minValue fields should
be consistent with the type returned by the
method for the associated
MBeanParameterInfo. For MXBeans, this means that they should be
of the mapped Java type, called opendata(J) in the MXBean type mapping rules.
|Default value for an attribute or parameter. See
|deprecated||String||Any||An indication that this element of the information model is no
longer recommended for use. A set of MBeans defined by an
application is collectively called an information model.
The convention is for the value of this field to contain a string
that is the version of the model in which the element was first
deprecated, followed by a space, followed by an explanation of the
deprecation, for example
|String||Any||The base name for the
|descriptionResourceKey||String||Any||A resource key for the description of this element. In
conjunction with the
|exceptions||String||MBeanAttributeInfo, MBeanConstructorInfo, MBeanOperationInfo||The class names of the exceptions that can be thrown when invoking a
constructor or operation, or getting an attribute. The meaning of this field
is defined by this specification but the field is not set or used by the
JMX API itself. Exceptions thrown when
setting an attribute are specified by the field
|MBeanInfo||The time in milli-seconds that the MBeanInfo can reasonably be
expected to be unchanged. The value can be a |
|interfaceClassName||String||MBeanInfo||The Java interface name for a Standard MBean or MXBean, as
|Legal values for an attribute or parameter. See
|locale||String||Any||The locale of the description in this
|Maximum legal value for an attribute or parameter. See
|The type of a metric, one of the strings "counter" or "gauge". A metric is a measurement exported by an MBean, usually an attribute but sometimes the result of an operation. A metric that is a counter has a value that never decreases except by being reset to a starting value. Counter metrics are almost always non-negative integers. An example might be the number of requests received. A metric that is a gauge has a numeric value that can increase or decrease. Examples might be the number of open connections or a cache hit rate or a temperature reading.|
|Minimum legal value for an attribute or parameter. See
The Open Type of this element. In the case of
This field can be set for an
The original Java type of this element as it appeared in the
The format of this string is described in the section Type Names of the MXBean specification.
|setExceptions||String||MBeanAttributeInfo||The class names of the exceptions that can be thrown when setting
an attribute. The meaning of this field
is defined by this specification but the field is not set or used by the
JMX API itself. Exceptions thrown when getting an attribute are specified
by the field |
|MBeanNotificationInfo||The severity of this notification. It can be 0 to mean
unknown severity or a value from 1 to 6 representing decreasing
levels of severity. It can be represented as a decimal string or
|since||String||Any||The version of the information model in which this element
was introduced. A set of MBeans defined by an application is
collectively called an information model. The
application may also define versions of this model, and use the
|The units in which an attribute, parameter, or operation return
value is measured, for example
Some additional fields are defined by Model MBeans. See the
well as the chapter "Model MBeans" of the JMX
Specification. The following table summarizes these fields. Note
that when the Type in this table is Number, a String that is the decimal
representation of a Long can also be used.
Nothing prevents the use of these fields in MBeans that are not Model MBeans. The displayName, severity, and visibility fields are of interest outside Model MBeans, for example. But only Model MBeans have a predefined behavior for these fields.
|class||String||ModelMBeanOperationInfo||Class where method is defined (fully qualified).|
|How long cached value is valid: <0 never, =0 always, >0 seconds.|
|default||Object||ModelMBeanAttributeInfo||Default value for attribute.|
|descriptorType||String||Any||Type of descriptor, "mbean", "attribute", "constructor", "operation", or "notification".|
|displayName||String||Any||Human readable name of this item.|
|export||String||ModelMBeanInfo||Name to be used to export/expose this MBean so that it is findable by other JMX Agents.|
|getMethod||String||ModelMBeanAttributeInfo||Name of operation descriptor for get method.|
|When value was set.|
|t or T: log all notifications, f or F: log no notifications.|
|Fully qualified filename to log events to.|
|messageID||String||ModelMBeanNotificationInfo||Unique key for message text (to allow translation, analysis).|
|messageText||String||ModelMBeanNotificationInfo||Text of notification.|
|name||String||Any||Name of this item.|
|persistFile||String||ModelMBeanInfo||File name into which the MBean should be persisted.|
|persistLocation||String||ModelMBeanInfo||The fully qualified directory name where the MBean should be persisted (if appropriate).|
|Frequency of persist cycle in seconds. Used when persistPolicy is "OnTimer" or "NoMoreOftenThan".|
|One of: OnUpdate|OnTimer|NoMoreOftenThan|OnUnregister|Always|Never. See the section "MBean Descriptor Fields" in the JMX specification document.|
|presentationString||String||Any||XML formatted string to allow presentation of data.|
|protocolMap||Descriptor||ModelMBeanAttributeInfo||See the section "Protocol Map Support" in the JMX specification document. Mappings must be appropriate for the attribute and entries can be updated or augmented at runtime.|
|One of "constructor", "operation", "getter", or "setter".|
|setMethod||String||ModelMBeanAttributeInfo||Name of operation descriptor for set method.|
|severity||Number||ModelMBeanNotificationInfo||0-6 where 0: unknown; 1: non-recoverable; 2: critical, failure; 3: major, severe; 4: minor, marginal, error; 5: warning; 6: normal, cleared, informative|
|targetObject||Object||ModelMBeanOperationInfo||Object on which to execute this method.|
|targetType||String||ModelMBeanOperationInfo||type of object reference for targetObject. Can be: ObjectReference | Handle | EJBHandle | IOR | RMIReference.|
|Current (cached) value for attribute or operation.|
|visibility||Number||Any||1-4 where 1: always visible, 4: rarely visible.|
|Modifier and Type||Method and Description|
Returns a descriptor which is equal to this descriptor.
Compares this descriptor to the given object.
Returns all the field names in the descriptor.
Returns all of the fields contained in this descriptor as a string array.
Returns the value for a specific field name, or null if no value is present for that name.
Returns all the field values in the descriptor as an array of Objects.
Returns the hash code value for this descriptor.
Returns true if all of the fields have legal values given their names.
Removes a field from the descriptor.
Sets the value for a specific field name.
Sets all fields in the field names array to the new value with the same index in the field values array.
Object getFieldValue(String fieldName) throws RuntimeOperationsException
fieldName- the field name.
RuntimeOperationsException- if the field name is illegal.
void setField(String fieldName, Object fieldValue) throws RuntimeOperationsException
Sets the value for a specific field name. This will modify an existing field or add a new field.
The field value will be validated before it is set. If it is not valid, then an exception will be thrown. The meaning of validity is dependent on the descriptor implementation.
fieldName- The field name to be set. Cannot be null or empty.
fieldValue- The field value to be set for the field name. Can be null if that is a valid value for the field.
RuntimeOperationsException- if the field name or field value is illegal (wrapped exception is
IllegalArgumentException); or if the descriptor is immutable (wrapped exception is
fieldNamesString array parameter.
fieldNames- String array of the names of the fields that the values should be returned for. If the array is empty then an empty array will be returned. If the array is null then all values will be returned, as if the parameter were the array returned by
getFieldNames(). If a field name in the array does not exist, including the case where it is null or the empty string, then null is returned for the matching array element being returned.
fieldNamesis empty, you will get an empty array.
void removeField(String fieldName)
fieldName- String name of the field to be removed. If the field name is illegal or the field is not found, no exception is thrown.
RuntimeOperationsException- if a field of the given name exists and the descriptor is immutable. The wrapped exception will be an
void setFields(String fieldNames, Object fieldValues) throws RuntimeOperationsException
Sets all fields in the field names array to the new value with the same index in the field values array. Array sizes must match.
The field value will be validated before it is set. If it is not valid, then an exception will be thrown. If the arrays are empty, then no change will take effect.
fieldNames- String array of field names. The array and array elements cannot be null.
fieldValues- Object array of the corresponding field values. The array cannot be null. Elements of the array can be null.
RuntimeOperationsException- if the change fails for any reason. Wrapped exception is
fieldValuesis null, or if the arrays are of different lengths, or if there is an illegal value in one of them. Wrapped exception is
UnsupportedOperationExceptionif the descriptor is immutable, and the call would change its contents.
Object clone() throws RuntimeOperationsException
Returns a descriptor which is equal to this descriptor. Changes to the returned descriptor will have no effect on this descriptor, and vice versa. If this descriptor is immutable, it may fulfill this condition by returning itself.
RuntimeOperationsException- for illegal value for field names or field values. If the descriptor construction fails for any reason, this exception will be thrown.
boolean isValid() throws RuntimeOperationsException
RuntimeOperationsException- If the validity checking fails for any reason, this exception will be thrown. The method returns false if the descriptor is not valid, but throws this exception if the attempt to determine validity fails.
boolean equals(Object obj)
Compares this descriptor to the given object. The objects are equal if the given object is also a Descriptor, and if the two Descriptors have the same field names (possibly differing in case) and the same associated values. The respective values for a field in the two Descriptors are equal if the following conditions hold:
Arrays.deepEquals(Object,Object)must return true.
Object.equals(Object)must return true.
Returns the hash code value for this descriptor. The hash
code is computed as the sum of the hash codes for each field in
the descriptor. The hash code of a field with name
n.toLowerCase().hashCode() ^ h.
h is the hash code of
v, computed as
vis null then
vis a primitive array then
his computed using the appropriate overloading of
vis an object array then
his computed using
Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2022, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.