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| javax.management.Descriptor
All known Subclasses: javax.management.modelmbean.DescriptorSupport, javax.management.ImmutableDescriptor,
| Descriptor | | public interface Descriptor extends Serializable,Cloneable(Code) | | Additional metadata for a JMX element. A
Descriptor is associated with a
MBeanInfo ,
MBeanAttributeInfo , etc.
It consists of a collection of fields. A field is a name and an
associated value.
Field names are not case-sensitive. The names
descriptorType ,
descriptortype , and
DESCRIPTORTYPE are all equivalent.
However, the case that was used when the field was first set is preserved
in the result of the
Descriptor.getFields and
Descriptor.getFieldNames methods.
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.
The Descriptor methods that could modify the contents
of the descriptor will throw an exception
for an immutable descriptor. Immutable descriptors are usually
instances of
ImmutableDescriptor or a subclass. Mutable
descriptors are usually instances of
javax.management.modelmbean.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
JMX class. For example, the field
defaultValue is represented
by the constant
JMX.DEFAULT_VALUE_FIELD .
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
example.com might
have the name
com.example.interestLevel .
Note that the values in the
defaultValue ,
legalValues ,
maxValue , and
minValue fields should
be consistent with the type returned by the
getType() method for the associated
MBeanAttributeInfo or
MBeanParameterInfo . For MXBeans, this means that they should be
of the mapped Java type, called opendata(J) in the MXBean type mapping rules.
| Name | Type | Used in | Meaning |
|---|
| defaultValue | Object |
MBeanAttributeInfo
MBeanParameterInfo |
Default value for an attribute or parameter. See
javax.management.openmbean . |
| 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
"1.3 Replaced by the Capacity attribute" . |
descriptionResource
BundleBaseName | String | Any |
The base name for the
ResourceBundle in which the key given in
the
descriptionResourceKey field can be found, for example
"com.example.myapp.MBeanResources" . The meaning of this
field is defined by this specification but the field is not set or
used by the JMX API itself. |
| descriptionResourceKey | String | Any |
A resource key for the description of this element. In
conjunction with the
descriptionResourceBundleBaseName ,
this can be used to find a localized version of the description.
The meaning of this field is defined by this specification but the
field is not set or used by the JMX API itself. |
| enabled | String |
MBeanAttributeInfo
MBeanNotificationInfo
MBeanOperationInfo |
The string
"true" or
"false" according as this
item is enabled. When an attribute or operation is not enabled, it
exists but cannot currently be accessed. A user interface might
present it as a greyed-out item. For example, an attribute might
only be meaningful after the
start() method of an MBean has
been called, and is otherwise disabled. Likewise, a notification
might be disabled if it cannot currently be emitted but could be in
other circumstances. |
| immutableInfo | String |
MBeanInfo |
The string
"true" or
"false" according as this
MBean's MBeanInfo is immutable. When this field is true,
the MBeanInfo for the given MBean is guaranteed not to change over
the lifetime of the MBean. Hence, a client can read it once and
cache the read value. When this field is false or absent, there is
no such guarantee, although that does not mean that the MBeanInfo
will necessarily change. |
| infoTimeout | String
Long | MBeanInfo |
The time in milli-seconds that the MBeanInfo can reasonably be
expected to be unchanged. The value can be a
Long or a
decimal string. This provides a hint from a DynamicMBean or any
MBean that does not define
immutableInfo as
true that the MBeanInfo is not likely to change within this period and
therefore can be cached. When this field is missing or has the
value zero, it is not recommended to cache the MBeanInfo unless it
has the
immutableInfo set to
true . |
| interfaceClassName |
String | MBeanInfo |
The Java interface name for a Standard MBean or MXBean, as
returned by
Class.getName . A Standard MBean or MXBean
registered directly in the MBean Server or created using the
StandardMBean class will have this field in its MBeanInfo
Descriptor. |
| legalValues |
| MBeanAttributeInfo
MBeanParameterInfo |
Legal values for an attribute or parameter. See
javax.management.openmbean . |
| maxValue | Object |
MBeanAttributeInfo
MBeanParameterInfo |
Maximum legal value for an attribute or parameter. See
javax.management.openmbean . |
| metricType | String |
MBeanAttributeInfo
MBeanOperationInfo |
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.
| | minValue | Object |
MBeanAttributeInfo
MBeanParameterInfo |
Minimum legal value for an attribute or parameter. See
javax.management.openmbean . |
| mxbean | String |
MBeanInfo |
The string
"true" or
"false" according as this
MBean is an
MXBean . A Standard MBean or MXBean registered
directly with the MBean Server or created using the
StandardMBean class will have this field in its MBeanInfo
Descriptor. |
| openType |
OpenType |
MBeanAttributeInfo
MBeanOperationInfo
MBeanParameterInfo |
The Open Type of this element. In the case of
MBeanAttributeInfo and
MBeanParameterInfo , this is the
Open Type of the attribute or parameter. In the case of
MBeanOperationInfo , it is the Open Type of the return value. This
field is set in the Descriptor for all instances of
OpenMBeanAttributeInfoSupport ,
OpenMBeanOperationInfoSupport , and
OpenMBeanParameterInfoSupport . It is also set for attributes,
operations, and parameters of MXBeans.
This field can be set for an
MBeanNotificationInfo , in
which case it indicates the Open Type that the
Notification.getUserData user data will have. |
| originalType | String |
MBeanAttributeInfo
MBeanOperationInfo
MBeanParameterInfo |
The original Java type of this element as it appeared in the
MXBean interface method that produced this
MBeanAttributeInfo (etc). For example, a method
public
MemoryUsage getHeapMemoryUsage();
in an MXBean interface defines an attribute called
HeapMemoryUsage of type
CompositeData . The
originalType field in the Descriptor for this attribute will have
the value
"java.lang.management.MemoryUsage" .
The format of this string is described in the section Type Names of the MXBean
specification.
| | severity | String
Integer |
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
an
Integer . |
| 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
"since" field to record the version in which an element
first appeared. |
| units | String |
MBeanAttributeInfo
MBeanParameterInfo
MBeanOperationInfo |
The units in which an attribute, parameter, or operation return
value is measured, for example
"bytes" or
"seconds" . |
Some additional fields are defined by Model MBeans. See
javax.management.modelmbean.ModelMBeanInfo ModelMBeanInfo and related classes and the chapter "Model MBeans" of the
JMX Specification.
since:
1.5 |
| Method Summary | |
| public Object | clone()
Returns a descriptor which is equal to this descriptor.
Changes to the returned descriptor will have no effect on this
descriptor, and vice versa. | | public boolean | equals(Object obj)
Compares this descriptor to the given object. | | public String[] | getFieldNames()
Returns all the field names in the descriptor.
String array of field names. | | public Object | getFieldValue(String fieldName)
Returns the value for a specific field name, or null if no value
is present for that name.
Parameters:
fieldName - the field name. | | public Object[] | getFieldValues(String... fieldNames)
Returns all the field values in the descriptor as an array of Objects. | | public String[] | getFields()
Returns all of the fields contained in this descriptor as a string array.
String array of fields in the format fieldName=fieldValue
If the value of a field is not a String, then the toString() methodwill be called on it and the returned value, enclosed in parentheses,used as the value for the field in the returned array. | | public int | hashCode()
Returns the hash code value for this descriptor. | | public boolean | isValid()
Returns true if all of the fields have legal values given their
names. | | public void | removeField(String fieldName)
Removes a field from the descriptor.
Parameters:
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.
exception:
RuntimeOperationsException - if a field of the given nameexists and the descriptor is immutable. | | public void | setField(String fieldName, Object fieldValue)
Sets the value for a specific field name. | | public void | setFields(String[] fieldNames, Object[] fieldValues)
Sets all fields in the field names array to the new value with
the same index in the field values array. |
| clone | | public Object clone() throws RuntimeOperationsException(Code) | | 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.
exception:
RuntimeOperationsException - for illegal value for field namesor field values.If the descriptor construction fails for any reason, this exception willbe thrown. A descriptor which is equal to this descriptor. |
| equals | | public boolean equals(Object obj)(Code) | | 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:
- If one value is null then the other must be too.
- If one value is a primitive array then the other must be a primitive
array of the same type with the same elements.
- If one value is an object array then the other must be too and
Arrays.deepEquals(Object[]Object[]) must return true.
- Otherwise
Object.equals(Object) must return true.
Parameters:
obj - the object to compare with. true if the objects are the same; false otherwise.
since:
1.6 |
| getFieldNames | | public String[] getFieldNames()(Code) | | Returns all the field names in the descriptor.
String array of field names. If the descriptor is empty,you will get an empty array. |
| getFieldValue | | public Object getFieldValue(String fieldName) throws RuntimeOperationsException(Code) | | Returns the value for a specific field name, or null if no value
is present for that name.
Parameters:
fieldName - the field name. the corresponding value, or null if the field is not present.
exception:
RuntimeOperationsException - if the field name is illegal. |
| getFieldValues | | public Object[] getFieldValues(String... fieldNames)(Code) | | Returns all the field values in the descriptor as an array of Objects. The
returned values are in the same order as the
fieldNames String array parameter.
Parameters:
fieldNames - String array of the names of the fields thatthe values should be returned for. If the array is empty thenan empty array will be returned. If the array is null then allvalues will be returned, as if the parameter were the arrayreturned by Descriptor.getFieldNames(). If a field name in thearray does not exist, including the case where it is null orthe empty string, then null is returned for the matching arrayelement being returned. Object array of field values. If the list of fieldNames is empty, you will get an empty array. |
| getFields | | public String[] getFields()(Code) | | Returns all of the fields contained in this descriptor as a string array.
String array of fields in the format fieldName=fieldValue
If the value of a field is not a String, then the toString() methodwill be called on it and the returned value, enclosed in parentheses,used as the value for the field in the returned array. If the valueof a field is null, then the value of the field in the returned arraywill be empty. If the descriptor is empty, you will getan empty array.
See Also: Descriptor.setFields |
| hashCode | | public int hashCode()(Code) | | 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 and value
v is
n.toLowerCase().hashCode() ^ h .
Here
h is the hash code of
v , computed as
follows:
- If
v is null then
h is 0.
- If
v is a primitive array then
h is computed using
the appropriate overloading of
java.util.Arrays.hashCode .
- If
v is an object array then
h is computed using
Arrays.deepHashCode(Object[]) .
- Otherwise
h is
v.hashCode() .
A hash code value for this object.
since:
1.6 |
| isValid | | public boolean isValid() throws RuntimeOperationsException(Code) | | Returns true if all of the fields have legal values given their
names.
true if the values are legal.
exception:
RuntimeOperationsException - If the validity checking fails forany reason, this exception will be thrown.The method returns false if the descriptor is not valid, but throwsthis exception if the attempt to determine validity fails. |
| removeField | | public void removeField(String fieldName)(Code) | | Removes a field from the descriptor.
Parameters:
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.
exception:
RuntimeOperationsException - if a field of the given nameexists and the descriptor is immutable. The wrapped exception willbe an UnsupportedOperationException. |
| setField | | public void setField(String fieldName, Object fieldValue) throws RuntimeOperationsException(Code) | | 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.
Parameters:
fieldName - The field name to be set. Cannot be null or empty.
Parameters:
fieldValue - The field value to be set for the fieldname. Can be null if that is a valid value for the field.
exception:
RuntimeOperationsException - if the field name or field valueis illegal (wrapped exception is IllegalArgumentException); orif the descriptor is immutable (wrapped exception isUnsupportedOperationException). |
| setFields | | public void setFields(String[] fieldNames, Object[] fieldValues) throws RuntimeOperationsException(Code) | | 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.
Parameters:
fieldNames - String array of field names. The array and arrayelements cannot be null.
Parameters:
fieldValues - Object array of the corresponding field values.The array cannot be null. Elements of the array can be null.
throws:
RuntimeOperationsException - if the change fails for any reason.Wrapped exception is IllegalArgumentException if fieldNames or fieldValues is null, or ifthe arrays are of different lengths, or if there is anillegal value in one of them.Wrapped exception is UnsupportedOperationExceptionif the descriptor is immutable, and the call would changeits contents.
See Also: Descriptor.getFields |
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