Java example source code file (DescriptorKey.java)

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Java - Java tags/keywords

annotation, descriptorkey, documented, string

The DescriptorKey.java Java example source code

/*
 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javax.management;

import java.lang.annotation.*;

/**
 * <p>Meta-annotation that describes how an annotation element relates
 * to a field in a {@link 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.</p>
 *
 * <p>Consider this annotation for example:

 *
 * <pre>
 * @Documented
 * @Target(ElementType.METHOD)
 * @Retention(RetentionPolicy.RUNTIME)
 * public @interface Units {
 *     <b>@DescriptorKey("units")
 *     String value();
 * }
 * </pre>
 *
 * <p>and this use of the annotation:

 *
 * <pre>
 * public interface CacheControlMBean {
 *     <b>@Units("bytes")
 *     public long getCacheSize();
 * }
 * </pre>
 *
 * <p>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
 * {@link MBeanAttributeInfo} for this attribute will have a
 * {@code Descriptor} that has a field called {@code units} with
 * corresponding value {@code bytes}.</p>
 *
 * <p>Similarly, if the annotation looks like this:

 *
 * <pre>
 * @Documented
 * @Target(ElementType.METHOD)
 * @Retention(RetentionPolicy.RUNTIME)
 * public @interface Units {
 *     <b>@DescriptorKey("units")
 *     String value();
 *
 *     <b>@DescriptorKey("descriptionResourceKey")
 *     String resourceKey() default "";
 *
 *     <b>@DescriptorKey("descriptionResourceBundleBaseName")
 *     String resourceBundleBaseName() default "";
 * }
 * </pre>
 *
 * <p>and it is used like this:

 *
 * <pre>
 * public interface CacheControlMBean {
 *     <b>@Units("bytes",
 *            resourceKey="bytes.key",
 *            resourceBundleBaseName="com.example.foo.MBeanResources")</b>
 *     public long getCacheSize();
 * }
 * </pre>
 *
 * <p>then the resulting {@code Descriptor} will contain the following
 * fields:</p>
 *
 * <table border="2" summary="Descriptor Fields">
 * <tr>