Annotation Type DescriptorFields
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@Documented @Inherited @Target({CONSTRUCTOR,METHOD,FIELD,PARAMETER,TYPE}) @Retention(RUNTIME) public @interface DescriptorFields
This is taken directly from JDK 7 in order to support this feature in JDK 5.Annotation that adds fields to a Descriptor. This can be the Descriptor for an MBean, or for an attribute, operation, or constructor in an MBean, or for a parameter of an operation or constructor.
Consider this Standard MBean interface, for example:
public interface CacheControlMBean { @DescriptorFields("units=bytes") public long getCacheSize(); }
When a Standard MBean is made using this interface, the usual rules mean that it will have an attribute called
CacheSize
of typelong
. TheDescriptorFields
annotation will ensure that the MBeanAttributeInfo for this attribute will have aDescriptor
that has a field calledunits
with corresponding valuebytes
.Similarly, if the interface looks like this:
public interface CacheControlMBean { @DescriptorFields({"units=bytes", "since=1.5"}) public long getCacheSize(); }
then the resulting
Descriptor
will contain the following fields:Descriptor
fieldsName Value units "bytes" since "1.5" The
@DescriptorFields
annotation can be applied to:- a Standard MBean or MXBean interface;
- a method in such an interface;
- a parameter of a method in a Standard MBean or MXBean interface when that method is an operation (not a getter or setter for an attribute);
- a public constructor in the class that implements a Standard MBean or MXBean;
- a parameter in such a constructor.
Other uses of the annotation will either fail to compile or be ignored.
Interface annotations are checked only on the exact interface that defines the management interface of a Standard MBean or an MXBean, not on its parent interfaces. Method annotations are checked only in the most specific interface in which the method appears; in other words, if a child interface overrides a method from a parent interface, only
@DescriptorFields
annotations in the method in the child interface are considered.The Descriptor fields contributed in this way must be consistent with each other and with any fields contributed by DescriptorKey annotations. That is, two different annotations, or two members of the same annotation, must not define a different value for the same Descriptor field. Fields from annotations on a getter method must also be consistent with fields from annotations on the corresponding setter method.
The Descriptor resulting from these annotations will be merged with any Descriptor fields provided by the implementation, such as the
immutableInfo
field for an MBean. The fields from the annotations must be consistent with these fields provided by the implementation.@DescriptorFields and @DescriptorKey
The DescriptorKey annotation provides another way to use annotations to define Descriptor fields.
@DescriptorKey
requires more work but is also more robust, because there is less risk of mistakes such as misspelling the name of the field or giving an invalid value.@DescriptorFields
is more convenient but includes those risks.@DescriptorFields
is more appropriate for occasional use, but for a Descriptor field that you add in many places, you should consider a purpose-built annotation using@DescriptorKey
.- Since:
- 1.7
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Required Element Summary
Required Elements Modifier and Type Required Element Description java.lang.String[]
value
The descriptor fields.
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