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/*
* Copyright (c) 2005, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.glassfish.gmbal;
import java.lang.annotation.*;
/** This is taken directly from JDK 7 in order to support this feature in
* JDK 5.
*
* Meta-annotation that describes how an annotation element relates
* to a field in 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.
*
* (The DescriptorFields annotation
* provides another way to add fields to a {@code Descriptor}. See
* the documentation for that annotation for a comparison of the
* two possibilities.)
*
* Consider this annotation for example:
*
*
* @Documented
* @Target(ElementType.METHOD)
* @Retention(RetentionPolicy.RUNTIME)
* public @interface Units {
* @DescriptorKey("units")
* String value();
* }
*
*
* and this use of the annotation:
*
*
* public interface CacheControlMBean {
* @Units("bytes")
* public long getCacheSize();
* }
*
*
* When a Standard MBean is made from the {@code CacheControlMBean},
* the usual rules mean that it will have an attribute called
* {@code CacheSize} of type {@code long}. The {@code @Units}
* annotation, given the above definition, will ensure that the
* MBeanAttributeInfo for this attribute will have a
* {@code Descriptor} that has a field called {@code units} with
* corresponding value {@code bytes}.
*
* Similarly, if the annotation looks like this:
*
*
* @Documented
* @Target(ElementType.METHOD)
* @Retention(RetentionPolicy.RUNTIME)
* public @interface Units {
* @DescriptorKey("units")
* String value();
*
* @DescriptorKey("descriptionResourceKey")
* String resourceKey() default "";
*
* @DescriptorKey("descriptionResourceBundleBaseName")
* String resourceBundleBaseName() default "";
* }
*
*
* and it is used like this:
*
*
* public interface CacheControlMBean {
* @Units("bytes",
* resourceKey="bytes.key",
* resourceBundleBaseName="com.example.foo.MBeanResources")
* public long getCacheSize();
* }
*
*
* then the resulting {@code Descriptor} will contain the following
* fields:
*
*
* Name Value units "bytes" descriptionResourceKey "bytes.key" descriptionResourceBundleBaseName
* "com.example.foo.MBeanResources"
*
* An annotation such as {@code @Units} 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 are 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 {@code @DescriptorKey} annotations in
* the method in the child interface are considered.
*
*
The Descriptor fields contributed in this way by different
* annotations on the same program element must be consistent with
* each other and with any fields contributed by a
* DescriptorFields annotation. 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 {@code
* immutableInfo} field for an MBean. The fields from the annotations
* must be consistent with these fields provided by the implementation.
*
* An annotation element to be converted into a descriptor field
* can be of any type allowed by the Java language, except an annotation
* or an array of annotations. The value of the field is derived from
* the value of the annotation element as follows:
*
*
* Annotation element Descriptor field Primitive value ({@code 5}, {@code false}, etc)
* Wrapped value ({@code Integer.valueOf(5)},
* {@code Boolean.FALSE}, etc) Class constant (e.g. {@code Thread.class})
* Class name from Class.getName()
* (e.g. {@code "java.lang.Thread"}) Enum constant (e.g. ElementType.FIELD)
* Constant name from Enum.name()
* (e.g. {@code "FIELD"}) Array of class constants or enum constants
* String array derived by applying these rules to each
* element Value of any other type
* ({@code String}, {@code String[]}, {@code int[]}, etc)
* The same value
*
* @since 1.6
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD, ElementType.FIELD })
public @interface DescriptorKey {
String value();
/**
* Do not include this field in the Descriptor if the annotation
* element has its default value. For example, suppose {@code @Units} is
* defined like this:
*
*
* @Documented
* @Target(ElementType.METHOD)
* @Retention(RetentionPolicy.RUNTIME)
* public @interface Units {
* @DescriptorKey("units")
* String value();
*
* @DescriptorKey(value = "descriptionResourceKey",
* omitIfDefault = true)
* String resourceKey() default "";
*
* @DescriptorKey(value = "descriptionResourceBundleBaseName",
* omitIfDefault = true)
* String resourceBundleBaseName() default "";
* }
*
*
* Then consider a usage such as {@code @Units("bytes")} or
* {@code @Units(value = "bytes", resourceKey = "")}, where the
* {@code resourceKey} and {@code resourceBundleBaseNames} elements
* have their default values. In this case the Descriptor resulting
* from these annotations will not include a {@code descriptionResourceKey}
* or {@code descriptionResourceBundleBaseName} field.
*/
boolean omitIfDefault() default false;
}