org.glassfish.gmbal.DescriptorFields Maven / Gradle / Ivy
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/*
* Copyright (c) 2007, 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.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/** 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 {@code CacheSize} of type
* {@code long}. The {@code DescriptorFields} annotation 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 interface looks like this:
*
*
* public interface CacheControlMBean {
* @DescriptorFields({"units=bytes", "since=1.5"})
* public long getCacheSize();
* }
*
*
* then the resulting {@code Descriptor} will contain the following
* fields:
*
*
* Name Value units "bytes" since "1.5"
*
* The {@code @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 {@code @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 {@code
* immutableInfo} field for an MBean. The fields from the annotations
* must be consistent with these fields provided by the implementation.
*
* {@literal @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
*/
@Documented
@Inherited // for @MBean and @MXBean classes
@Target({ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.FIELD,
ElementType.PARAMETER, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface DescriptorFields {
/**
*
The descriptor fields. Each element of the string looks like
* {@code "name=value"}.
*/
public String[] value();
}