| /* | |
| * Copyright (c) 1999, 2024, 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.StreamCorruptedException; | |
| import java.io.Serializable; | |
| import java.io.ObjectOutputStream; | |
| import java.io.ObjectInputStream; | |
| import java.lang.reflect.Method; | |
| import java.util.Arrays; | |
| import java.util.Map; | |
| import java.util.WeakHashMap; | |
| import java.util.Objects; | |
| import static javax.management.ImmutableDescriptor.nonNullDescriptor; | |
| /** | |
| * <p>Describes the management interface exposed by an MBean; that is, | |
| * the set of attributes and operations which are available for | |
| * management operations. Instances of this class are immutable. | |
| * Subclasses may be mutable but this is not recommended.</p> | |
| * | |
| * <p id="info-changed">Usually the {@code MBeanInfo} for any given MBean does | |
| * not change over the lifetime of that MBean. Dynamic MBeans can change their | |
| * {@code MBeanInfo} and in that case it is recommended that they emit a {@link | |
| * Notification} with a {@linkplain Notification#getType() type} of {@code | |
| * "jmx.mbean.info.changed"} and a {@linkplain Notification#getUserData() | |
| * userData} that is the new {@code MBeanInfo}. This is not required, but | |
| * provides a conventional way for clients of the MBean to discover the change. | |
| * See also the <a href="Descriptor.html#immutableInfo">immutableInfo</a> and | |
| * <a href="Descriptor.html#infoTimeout">infoTimeout</a> fields in the {@code | |
| * MBeanInfo} {@link Descriptor}.</p> | |
| * | |
| * <p>The contents of the {@code MBeanInfo} for a Dynamic MBean | |
| * are determined by its {@link DynamicMBean#getMBeanInfo | |
| * getMBeanInfo()} method. This includes Open MBeans and Model | |
| * MBeans, which are kinds of Dynamic MBeans.</p> | |
| * | |
| * <p>The contents of the {@code MBeanInfo} for a Standard MBean | |
| * are determined by the MBean server as follows:</p> | |
| * | |
| * <ul> | |
| * | |
| * <li>{@link #getClassName()} returns the Java class name of the MBean | |
| * object; | |
| * | |
| * <li>{@link #getConstructors()} returns the list of all public | |
| * constructors in that object; | |
| * | |
| * <li>{@link #getAttributes()} returns the list of all attributes | |
| * whose existence is deduced from the presence in the MBean interface | |
| * of a <code>get<i>Name</i></code>, <code>is<i>Name</i></code>, or | |
| * <code>set<i>Name</i></code> method that conforms to the conventions | |
| * for Standard MBeans; | |
| * | |
| * <li>{@link #getOperations()} returns the list of all methods in | |
| * the MBean interface that do not represent attributes; | |
| * | |
| * <li>{@link #getNotifications()} returns an empty array if the MBean | |
| * does not implement the {@link NotificationBroadcaster} interface, | |
| * otherwise the result of calling {@link | |
| * NotificationBroadcaster#getNotificationInfo()} on it; | |
| * | |
| * <li>{@link #getDescriptor()} returns a descriptor containing the contents | |
| * of any descriptor annotations in the MBean interface (see | |
| * {@link DescriptorKey @DescriptorKey}). | |
| * | |
| * </ul> | |
| * | |
| * <p>The description returned by {@link #getDescription()} and the | |
| * descriptions of the contained attributes and operations are not specified.</p> | |
| * | |
| * <p>The remaining details of the {@code MBeanInfo} for a | |
| * Standard MBean are not specified. This includes the description of | |
| * any contained constructors, and notifications; the names | |
| * of parameters to constructors and operations; and the descriptions of | |
| * constructor parameters.</p> | |
| * | |
| * @since 1.5 | |
| */ | |
| public class MBeanInfo implements Cloneable, Serializable, DescriptorRead { | |
| /* Serial version */ | |
| static final long serialVersionUID = -6451021435135161911L; | |
| /** | |
| * @serial The Descriptor for the MBean. This field | |
| * can be null, which is equivalent to an empty Descriptor. | |
| */ | |
| private transient Descriptor descriptor; | |
| /** | |
| * @serial The human readable description of the class. | |
| */ | |
| private final String description; | |
| /** | |
| * @serial The MBean qualified name. | |
| */ | |
| private final String className; | |
| /** | |
| * @serial The MBean attribute descriptors. | |
| */ | |
| private final MBeanAttributeInfo[] attributes; | |
| /** | |
| * @serial The MBean operation descriptors. | |
| */ | |
| private final MBeanOperationInfo[] operations; | |
| /** | |
| * @serial The MBean constructor descriptors. | |
| */ | |
| private final MBeanConstructorInfo[] constructors; | |
| /** | |
| * @serial The MBean notification descriptors. | |
| */ | |
| private final MBeanNotificationInfo[] notifications; | |
| private transient int hashCode; | |
| /** | |
| * <p>True if this class is known not to override the array-valued | |
| * getters of MBeanInfo. Obviously true for MBeanInfo itself, and true | |
| * for a subclass where we succeed in reflecting on the methods | |
| * and discover they are not overridden.</p> | |
| * | |
| * <p>The purpose of this variable is to avoid cloning the arrays | |
| * when doing operations like {@link #equals} where we know they | |
| * will not be changed. If a subclass overrides a getter, we | |
| * cannot access the corresponding array directly.</p> | |
| */ | |
| private final transient boolean arrayGettersSafe; | |
| /** | |
| * Constructs an {@code MBeanInfo}. | |
| * | |
| * @param className The name of the Java class of the MBean described | |
| * by this {@code MBeanInfo}. This value may be any | |
| * syntactically legal Java class name. It does not have to be a | |
| * Java class known to the MBean server or to the MBean's | |
| * ClassLoader. If it is a Java class known to the MBean's | |
| * ClassLoader, it is recommended but not required that the | |
| * class's public methods include those that would appear in a | |
| * Standard MBean implementing the attributes and operations in | |
| * this MBeanInfo. | |
| * @param description A human readable description of the MBean (optional). | |
| * @param attributes The list of exposed attributes of the MBean. | |
| * This may be null with the same effect as a zero-length array. | |
| * @param constructors The list of public constructors of the | |
| * MBean. This may be null with the same effect as a zero-length | |
| * array. | |
| * @param operations The list of operations of the MBean. This | |
| * may be null with the same effect as a zero-length array. | |
| * @param notifications The list of notifications emitted. This | |
| * may be null with the same effect as a zero-length array. | |
| */ | |
| public MBeanInfo(String className, | |
| String description, | |
| MBeanAttributeInfo[] attributes, | |
| MBeanConstructorInfo[] constructors, | |
| MBeanOperationInfo[] operations, | |
| MBeanNotificationInfo[] notifications) | |
| throws IllegalArgumentException { | |
| this(className, description, attributes, constructors, operations, | |
| notifications, null); | |
| } | |
| /** | |
| * Constructs an {@code MBeanInfo}. | |
| * | |
| * @param className The name of the Java class of the MBean described | |
| * by this {@code MBeanInfo}. This value may be any | |
| * syntactically legal Java class name. It does not have to be a | |
| * Java class known to the MBean server or to the MBean's | |
| * ClassLoader. If it is a Java class known to the MBean's | |
| * ClassLoader, it is recommended but not required that the | |
| * class's public methods include those that would appear in a | |
| * Standard MBean implementing the attributes and operations in | |
| * this MBeanInfo. | |
| * @param description A human readable description of the MBean (optional). | |
| * @param attributes The list of exposed attributes of the MBean. | |
| * This may be null with the same effect as a zero-length array. | |
| * @param constructors The list of public constructors of the | |
| * MBean. This may be null with the same effect as a zero-length | |
| * array. | |
| * @param operations The list of operations of the MBean. This | |
| * may be null with the same effect as a zero-length array. | |
| * @param notifications The list of notifications emitted. This | |
| * may be null with the same effect as a zero-length array. | |
| * @param descriptor The descriptor for the MBean. This may be null | |
| * which is equivalent to an empty descriptor. | |
| * | |
| * @since 1.6 | |
| */ | |
| public MBeanInfo(String className, | |
| String description, | |
| MBeanAttributeInfo[] attributes, | |
| MBeanConstructorInfo[] constructors, | |
| MBeanOperationInfo[] operations, | |
| MBeanNotificationInfo[] notifications, | |
| Descriptor descriptor) | |
| throws IllegalArgumentException { | |
| this.className = className; | |
| this.description = description; | |
| if (attributes == null) | |
| attributes = MBeanAttributeInfo.NO_ATTRIBUTES; | |
| this.attributes = attributes; | |
| if (operations == null) | |
| operations = MBeanOperationInfo.NO_OPERATIONS; | |
| this.operations = operations; | |
| if (constructors == null) | |
| constructors = MBeanConstructorInfo.NO_CONSTRUCTORS; | |
| this.constructors = constructors; | |
| if (notifications == null) | |
| notifications = MBeanNotificationInfo.NO_NOTIFICATIONS; | |
| this.notifications = notifications; | |
| if (descriptor == null) | |
| descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR; | |
| this.descriptor = descriptor; | |
| this.arrayGettersSafe = | |
| arrayGettersSafe(this.getClass(), MBeanInfo.class); | |
| } | |
| /** | |
| * <p>Returns a shallow clone of this instance. | |
| * The clone is obtained by simply calling {@code super.clone()}, | |
| * thus calling the default native shallow cloning mechanism | |
| * implemented by {@code Object.clone()}. | |
| * No deeper cloning of any internal field is made.</p> | |
| * | |
| * <p>Since this class is immutable, the clone method is chiefly of | |
| * interest to subclasses.</p> | |
| */ | |
| @Override | |
| public Object clone () { | |
| try { | |
| return super.clone() ; | |
| } catch (CloneNotSupportedException e) { | |
| // should not happen as this class is cloneable | |
| return null; | |
| } | |
| } | |
| /** | |
| * Returns the name of the Java class of the MBean described by | |
| * this {@code MBeanInfo}. | |
| * | |
| * @return the class name. | |
| */ | |
| public String getClassName() { | |
| return className; | |
| } | |
| /** | |
| * Returns a human readable description of the MBean. | |
| * | |
| * @return the description. | |
| */ | |
| public String getDescription() { | |
| return description; | |
| } | |
| /** | |
| * Returns the list of attributes exposed for management. | |
| * Each attribute is described by an {@code MBeanAttributeInfo} object. | |
| * | |
| * The returned array is a shallow copy of the internal array, | |
| * which means that it is a copy of the internal array of | |
| * references to the {@code MBeanAttributeInfo} objects | |
| * but that each referenced {@code MBeanAttributeInfo} object is not copied. | |
| * | |
| * @return An array of {@code MBeanAttributeInfo} objects. | |
| */ | |
| public MBeanAttributeInfo[] getAttributes() { | |
| MBeanAttributeInfo[] as = nonNullAttributes(); | |
| if (as.length == 0) | |
| return as; | |
| else | |
| return as.clone(); | |
| } | |
| private MBeanAttributeInfo[] fastGetAttributes() { | |
| if (arrayGettersSafe) | |
| return nonNullAttributes(); | |
| else | |
| return getAttributes(); | |
| } | |
| /** | |
| * Return the value of the attributes field, or an empty array if | |
| * the field is null. This can't happen with a | |
| * normally-constructed instance of this class, but can if the | |
| * instance was deserialized from another implementation that | |
| * allows the field to be null. It would be simpler if we enforced | |
| * the class invariant that these fields cannot be null by writing | |
| * a readObject() method, but that would require us to define the | |
| * various array fields as non-final, which is annoying because | |
| * conceptually they are indeed final. | |
| */ | |
| private MBeanAttributeInfo[] nonNullAttributes() { | |
| return (attributes == null) ? | |
| MBeanAttributeInfo.NO_ATTRIBUTES : attributes; | |
| } | |
| /** | |
| * Returns the list of operations of the MBean. | |
| * Each operation is described by an {@code MBeanOperationInfo} object. | |
| * | |
| * The returned array is a shallow copy of the internal array, | |
| * which means that it is a copy of the internal array of | |
| * references to the {@code MBeanOperationInfo} objects | |
| * but that each referenced {@code MBeanOperationInfo} object is not copied. | |
| * | |
| * @return An array of {@code MBeanOperationInfo} objects. | |
| */ | |
| public MBeanOperationInfo[] getOperations() { | |
| MBeanOperationInfo[] os = nonNullOperations(); | |
| if (os.length == 0) | |
| return os; | |
| else | |
| return os.clone(); | |
| } | |
| private MBeanOperationInfo[] fastGetOperations() { | |
| if (arrayGettersSafe) | |
| return nonNullOperations(); | |
| else | |
| return getOperations(); | |
| } | |
| private MBeanOperationInfo[] nonNullOperations() { | |
| return (operations == null) ? | |
| MBeanOperationInfo.NO_OPERATIONS : operations; | |
| } | |
| /** | |
| * <p>Returns the list of the public constructors of the MBean. | |
| * Each constructor is described by an | |
| * {@code MBeanConstructorInfo} object.</p> | |
| * | |
| * <p>The returned array is a shallow copy of the internal array, | |
| * which means that it is a copy of the internal array of | |
| * references to the {@code MBeanConstructorInfo} objects but | |
| * that each referenced {@code MBeanConstructorInfo} object | |
| * is not copied.</p> | |
| * | |
| * <p>The returned list is not necessarily exhaustive. That is, | |
| * the MBean may have a public constructor that is not in the | |
| * list. In this case, the MBean server can construct another | |
| * instance of this MBean's class using that constructor, even | |
| * though it is not listed here.</p> | |
| * | |
| * @return An array of {@code MBeanConstructorInfo} objects. | |
| */ | |
| public MBeanConstructorInfo[] getConstructors() { | |
| MBeanConstructorInfo[] cs = nonNullConstructors(); | |
| if (cs.length == 0) | |
| return cs; | |
| else | |
| return cs.clone(); | |
| } | |
| private MBeanConstructorInfo[] fastGetConstructors() { | |
| if (arrayGettersSafe) | |
| return nonNullConstructors(); | |
| else | |
| return getConstructors(); | |
| } | |
| private MBeanConstructorInfo[] nonNullConstructors() { | |
| return (constructors == null) ? | |
| MBeanConstructorInfo.NO_CONSTRUCTORS : constructors; | |
| } | |
| /** | |
| * Returns the list of the notifications emitted by the MBean. | |
| * Each notification is described by an {@code MBeanNotificationInfo} object. | |
| * | |
| * The returned array is a shallow copy of the internal array, | |
| * which means that it is a copy of the internal array of | |
| * references to the {@code MBeanNotificationInfo} objects | |
| * but that each referenced {@code MBeanNotificationInfo} object is not copied. | |
| * | |
| * @return An array of {@code MBeanNotificationInfo} objects. | |
| */ | |
| public MBeanNotificationInfo[] getNotifications() { | |
| MBeanNotificationInfo[] ns = nonNullNotifications(); | |
| if (ns.length == 0) | |
| return ns; | |
| else | |
| return ns.clone(); | |
| } | |
| private MBeanNotificationInfo[] fastGetNotifications() { | |
| if (arrayGettersSafe) | |
| return nonNullNotifications(); | |
| else | |
| return getNotifications(); | |
| } | |
| private MBeanNotificationInfo[] nonNullNotifications() { | |
| return (notifications == null) ? | |
| MBeanNotificationInfo.NO_NOTIFICATIONS : notifications; | |
| } | |
| /** | |
| * Get the descriptor of this MBeanInfo. 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) nonNullDescriptor(descriptor).clone(); | |
| } | |
| @Override | |
| public String toString() { | |
| return | |
| getClass().getName() + "[" + | |
| "description=" + getDescription() + ", " + | |
| "attributes=" + Arrays.asList(fastGetAttributes()) + ", " + | |
| "constructors=" + Arrays.asList(fastGetConstructors()) + ", " + | |
| "operations=" + Arrays.asList(fastGetOperations()) + ", " + | |
| "notifications=" + Arrays.asList(fastGetNotifications()) + ", " + | |
| "descriptor=" + getDescriptor() + | |
| "]"; | |
| } | |
| /** | |
| * <p>Compare this MBeanInfo to another. Two MBeanInfo objects | |
| * are equal if and only if they return equal values for {@link | |
| * #getClassName()}, for {@link #getDescription()}, and for | |
| * {@link #getDescriptor()}, and the | |
| * arrays returned by the two objects for {@link | |
| * #getAttributes()}, {@link #getOperations()}, {@link | |
| * #getConstructors()}, and {@link #getNotifications()} are | |
| * pairwise equal. Here "equal" means {@link | |
| * Object#equals(Object)}, not identity.</p> | |
| * | |
| * <p>If two MBeanInfo objects return the same values in one of | |
| * their arrays but in a different order then they are not equal.</p> | |
| * | |
| * @param o the object to compare to. | |
| * | |
| * @return true if and only if {@code o} is an MBeanInfo that is equal | |
| * to this one according to the rules above. | |
| */ | |
| @Override | |
| public boolean equals(Object o) { | |
| if (o == this) | |
| return true; | |
| if (!(o instanceof MBeanInfo)) | |
| return false; | |
| MBeanInfo p = (MBeanInfo) o; | |
| if (!isEqual(getClassName(), p.getClassName()) || | |
| !isEqual(getDescription(), p.getDescription()) || | |
| !getDescriptor().equals(p.getDescriptor())) { | |
| return false; | |
| } | |
| return | |
| (Arrays.equals(p.fastGetAttributes(), fastGetAttributes()) && | |
| Arrays.equals(p.fastGetOperations(), fastGetOperations()) && | |
| Arrays.equals(p.fastGetConstructors(), fastGetConstructors()) && | |
| Arrays.equals(p.fastGetNotifications(), fastGetNotifications())); | |
| } | |
| @Override | |
| public int hashCode() { | |
| /* Since computing the hashCode is quite expensive, we cache it. | |
| If by some terrible misfortune the computed value is 0, the | |
| caching won't work and we will recompute it every time. | |
| We don't bother synchronizing, because, at worst, n different | |
| threads will compute the same hashCode at the same time. */ | |
| if (hashCode != 0) | |
| return hashCode; | |
| hashCode = Objects.hash(getClassName(), getDescriptor()) | |
| ^ Arrays.hashCode(fastGetAttributes()) | |
| ^ Arrays.hashCode(fastGetOperations()) | |
| ^ Arrays.hashCode(fastGetConstructors()) | |
| ^ Arrays.hashCode(fastGetNotifications()); | |
| return hashCode; | |
| } | |
| /** | |
| * Cached results of previous calls to arrayGettersSafe. This is | |
| * a WeakHashMap so that we don't prevent a class from being | |
| * garbage collected just because we know whether it's immutable. | |
| */ | |
| private static final Map<Class<?>, Boolean> arrayGettersSafeMap = | |
| new WeakHashMap<>(); | |
| /** | |
| * Return true if {@code subclass} is known to preserve the | |
| * immutability of {@code immutableClass}. The class | |
| * {@code immutableClass} is a reference class that is known | |
| * to be immutable. The subclass {@code subclass} is | |
| * considered immutable if it does not override any public method | |
| * of {@code immutableClass} whose name begins with "get". | |
| * This is obviously not an infallible test for immutability, | |
| * but it works for the public interfaces of the MBean*Info classes. | |
| */ | |
| @SuppressWarnings("removal") | |
| static boolean arrayGettersSafe(Class<?> subclass, Class<?> immutableClass) { | |
| if (subclass == immutableClass) | |
| return true; | |
| synchronized (arrayGettersSafeMap) { | |
| Boolean safe = arrayGettersSafeMap.get(subclass); | |
| if (safe == null) { | |
| try { | |
| safe = arrayGettersSafeHelper(subclass, immutableClass); | |
| } catch (Exception e) { | |
| /* We don't know, so we assume it isn't. */ | |
| safe = false; | |
| } | |
| arrayGettersSafeMap.put(subclass, safe); | |
| } | |
| return safe; | |
| } | |
| } | |
| private static boolean arrayGettersSafeHelper(Class<?> subclass, Class<?> immutableClass) { | |
| Method[] methods = immutableClass.getMethods(); | |
| for (int i = 0; i < methods.length; i++) { | |
| Method method = methods[i]; | |
| String methodName = method.getName(); | |
| if (methodName.startsWith("get") && | |
| method.getParameterTypes().length == 0 && | |
| method.getReturnType().isArray()) { | |
| try { | |
| Method submethod = | |
| subclass.getMethod(methodName); | |
| if (!submethod.equals(method)) | |
| return false; | |
| } catch (NoSuchMethodException e) { | |
| return false; | |
| } | |
| } | |
| } | |
| return true; | |
| } | |
| private static boolean isEqual(String s1, String s2) { | |
| boolean ret; | |
| if (s1 == null) { | |
| ret = (s2 == null); | |
| } else { | |
| ret = s1.equals(s2); | |
| } | |
| return ret; | |
| } | |
| /** | |
| * Serializes an {@link MBeanInfo} 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 the field {@code descriptor} directly. | |
| * </ul> | |
| * | |
| * @since 1.6 | |
| */ | |
| private void writeObject(ObjectOutputStream out) throws IOException { | |
| out.defaultWriteObject(); | |
| if (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 MBeanInfo} 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."); | |
| } | |
| } | |
| } |