src/java.management/share/classes/javax/management/MBeanFeatureInfo.java
changeset 47216 71c04702a3d5
parent 37880 60ec48925dc6
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.management/share/classes/javax/management/MBeanFeatureInfo.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,265 @@
+/*
+ * Copyright (c) 1999, 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.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.io.StreamCorruptedException;
+import java.util.Objects;
+
+/**
+ * <p>Provides general information for an MBean descriptor object.
+ * The feature described can be an attribute, an operation, a
+ * parameter, or a notification.  Instances of this class are
+ * immutable.  Subclasses may be mutable but this is not
+ * recommended.</p>
+ *
+ * @since 1.5
+ */
+public class MBeanFeatureInfo implements Serializable, DescriptorRead {
+
+
+    /* Serial version */
+    static final long serialVersionUID = 3952882688968447265L;
+
+    /**
+     * The name of the feature.  It is recommended that subclasses call
+     * {@link #getName} rather than reading this field, and that they
+     * not change it.
+     *
+     * @serial The name of the feature.
+     */
+    protected String name;
+
+    /**
+     * The human-readable description of the feature.  It is
+     * recommended that subclasses call {@link #getDescription} rather
+     * than reading this field, and that they not change it.
+     *
+     * @serial The human-readable description of the feature.
+     */
+    protected String description;
+
+    /**
+     * @serial The Descriptor for this MBeanFeatureInfo.  This field
+     * can be null, which is equivalent to an empty Descriptor.
+     */
+    private transient Descriptor descriptor;
+
+
+    /**
+     * Constructs an <CODE>MBeanFeatureInfo</CODE> object.  This
+     * constructor is equivalent to {@code MBeanFeatureInfo(name,
+     * description, (Descriptor) null}.
+     *
+     * @param name The name of the feature.
+     * @param description A human readable description of the feature.
+     */
+    public MBeanFeatureInfo(String name, String description) {
+        this(name, description, null);
+    }
+
+    /**
+     * Constructs an <CODE>MBeanFeatureInfo</CODE> object.
+     *
+     * @param name The name of the feature.
+     * @param description A human readable description of the feature.
+     * @param descriptor The descriptor for the feature.  This may be null
+     * which is equivalent to an empty descriptor.
+     *
+     * @since 1.6
+     */
+    public MBeanFeatureInfo(String name, String description,
+                            Descriptor descriptor) {
+        this.name = name;
+        this.description = description;
+        this.descriptor = descriptor;
+    }
+
+    /**
+     * Returns the name of the feature.
+     *
+     * @return the name of the feature.
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * Returns the human-readable description of the feature.
+     *
+     * @return the human-readable description of the feature.
+     */
+    public String getDescription() {
+        return description;
+    }
+
+    /**
+     * Returns the descriptor for the feature.  Changing the returned value
+     * will have no affect on the original descriptor.
+     *
+     * @return a descriptor that is either immutable or a copy of the original.
+     *
+     * @since 1.6
+     */
+    public Descriptor getDescriptor() {
+        return (Descriptor) ImmutableDescriptor.nonNullDescriptor(descriptor).clone();
+    }
+
+    /**
+     * Compare this MBeanFeatureInfo to another.
+     *
+     * @param o the object to compare to.
+     *
+     * @return true if and only if <code>o</code> is an MBeanFeatureInfo such
+     * that its {@link #getName()}, {@link #getDescription()}, and
+     * {@link #getDescriptor()}
+     * values are equal (not necessarily identical) to those of this
+     * MBeanFeatureInfo.
+     */
+    public boolean equals(Object o) {
+        if (o == this)
+            return true;
+        if (!(o instanceof MBeanFeatureInfo))
+            return false;
+        MBeanFeatureInfo p = (MBeanFeatureInfo) o;
+        return (Objects.equals(p.getName(), getName()) &&
+                Objects.equals(p.getDescription(), getDescription()) &&
+                Objects.equals(p.getDescriptor(), getDescriptor()));
+    }
+
+    public int hashCode() {
+        return getName().hashCode() ^ getDescription().hashCode() ^
+               getDescriptor().hashCode();
+    }
+
+    /**
+     * Serializes an {@link MBeanFeatureInfo} to an {@link ObjectOutputStream}.
+     * @serialData
+     * For compatibility reasons, an object of this class is serialized as follows.
+     * <p>
+     * The method {@link ObjectOutputStream#defaultWriteObject defaultWriteObject()}
+     * is called first to serialize the object except the field {@code descriptor}
+     * which is declared as transient. The field {@code descriptor} is serialized
+     * as follows:
+     *     <ul>
+     *     <li>If {@code descriptor} is an instance of the class
+     *        {@link ImmutableDescriptor}, the method {@link ObjectOutputStream#write
+     *        write(int val)} is called to write a byte with the value {@code 1},
+     *        then the method {@link ObjectOutputStream#writeObject writeObject(Object obj)}
+     *        is called twice to serialize the field names and the field values of the
+     *        {@code descriptor}, respectively as a {@code String[]} and an
+     *        {@code Object[]};</li>
+     *     <li>Otherwise, the method {@link ObjectOutputStream#write write(int val)}
+     * is called to write a byte with the value {@code 0}, then the method
+     * {@link ObjectOutputStream#writeObject writeObject(Object obj)} is called
+     * to serialize directly the field {@code descriptor}.
+     *     </ul>
+     *
+     * @since 1.6
+     */
+    private void writeObject(ObjectOutputStream out) throws IOException {
+        out.defaultWriteObject();
+
+        if (descriptor != null &&
+            descriptor.getClass() == ImmutableDescriptor.class) {
+
+            out.write(1);
+
+            final String[] names = descriptor.getFieldNames();
+
+            out.writeObject(names);
+            out.writeObject(descriptor.getFieldValues(names));
+        } else {
+            out.write(0);
+
+            out.writeObject(descriptor);
+        }
+    }
+
+    /**
+     * Deserializes an {@link MBeanFeatureInfo} from an {@link ObjectInputStream}.
+     * @serialData
+     * For compatibility reasons, an object of this class is deserialized as follows.
+     * <p>
+     * The method {@link ObjectInputStream#defaultReadObject defaultReadObject()}
+     * is called first to deserialize the object except the field
+     * {@code descriptor}, which is not serialized in the default way. Then the method
+     * {@link ObjectInputStream#read read()} is called to read a byte, the field
+     * {@code descriptor} is deserialized according to the value of the byte value:
+     *    <ul>
+     *    <li>1. The method {@link ObjectInputStream#readObject readObject()}
+     *       is called twice to obtain the field names (a {@code String[]}) and
+     *       the field values (an {@code Object[]}) of the {@code descriptor}.
+     *       The two obtained values then are used to construct
+     *       an {@link ImmutableDescriptor} instance for the field
+     *       {@code descriptor};</li>
+     *    <li>0. The value for the field {@code descriptor} is obtained directly
+     *       by calling the method {@link ObjectInputStream#readObject readObject()}.
+     *       If the obtained value is null, the field {@code descriptor} is set to
+     *       {@link ImmutableDescriptor#EMPTY_DESCRIPTOR EMPTY_DESCRIPTOR};</li>
+     *    <li>-1. This means that there is no byte to read and that the object is from
+     *       an earlier version of the JMX API. The field {@code descriptor} is set
+     *       to {@link ImmutableDescriptor#EMPTY_DESCRIPTOR EMPTY_DESCRIPTOR}</li>
+     *    <li>Any other value. A {@link StreamCorruptedException} is thrown.</li>
+     *    </ul>
+     *
+     * @since 1.6
+     */
+    private void readObject(ObjectInputStream in)
+        throws IOException, ClassNotFoundException {
+
+        in.defaultReadObject();
+
+        switch (in.read()) {
+        case 1:
+            final String[] names = (String[])in.readObject();
+
+            final Object[] values = (Object[]) in.readObject();
+            descriptor = (names.length == 0) ?
+                ImmutableDescriptor.EMPTY_DESCRIPTOR :
+                new ImmutableDescriptor(names, values);
+
+            break;
+        case 0:
+            descriptor = (Descriptor)in.readObject();
+
+            if (descriptor == null) {
+                descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR;
+            }
+
+            break;
+        case -1: // from an earlier version of the JMX API
+            descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR;
+
+            break;
+        default:
+            throw new StreamCorruptedException("Got unexpected byte.");
+        }
+    }
+}