author | mchung |
Fri, 24 Aug 2012 22:55:49 -0700 | |
changeset 13589 | da4cb574f4a6 |
parent 5506 | 202f599c92aa |
child 14342 | 8435a30053c1 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 2007, 2008, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package com.sun.jmx.mbeanserver; |
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import java.io.InvalidObjectException; |
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import java.lang.reflect.Type; |
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import javax.management.openmbean.OpenDataException; |
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import javax.management.openmbean.OpenType; |
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/** |
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* <p>A custom mapping between Java types and Open types for use in MXBeans. |
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* To define such a mapping, subclass this class and define at least the |
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* {@link #fromOpenValue fromOpenValue} and {@link #toOpenValue toOpenValue} |
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* methods, and optionally the {@link #checkReconstructible} method. |
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* Then either use an {@link MXBeanMappingClass} annotation on your custom |
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* Java types, or include this MXBeanMapping in an |
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* {@link MXBeanMappingFactory}.</p> |
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* |
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* <p>For example, suppose we have a class {@code MyLinkedList}, which looks |
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* like this:</p> |
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* |
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* <pre> |
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* public class MyLinkedList { |
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* public MyLinkedList(String name, MyLinkedList next) {...} |
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* public String getName() {...} |
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* public MyLinkedList getNext() {...} |
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* } |
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* </pre> |
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* |
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* <p>This is not a valid type for MXBeans, because it contains a |
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* self-referential property "next" defined by the {@code getNext()} |
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* method. MXBeans do not support recursive types. So we would like |
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* to specify a mapping for {@code MyLinkedList} explicitly. When an |
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* MXBean interface contains {@code MyLinkedList}, that will be mapped |
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* into a {@code String[]}, which is a valid Open Type.</p> |
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* |
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* <p>To define this mapping, we first subclass {@code MXBeanMapping}:</p> |
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* |
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* <pre> |
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* public class MyLinkedListMapping extends MXBeanMapping { |
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* public MyLinkedListMapping(Type type) throws OpenDataException { |
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* super(MyLinkedList.class, ArrayType.getArrayType(SimpleType.STRING)); |
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* if (type != MyLinkedList.class) |
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* throw new OpenDataException("Mapping only valid for MyLinkedList"); |
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* } |
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* |
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* {@literal @Override} |
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* public Object fromOpenValue(Object openValue) throws InvalidObjectException { |
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* String[] array = (String[]) openValue; |
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* MyLinkedList list = null; |
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* for (int i = array.length - 1; i >= 0; i--) |
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* list = new MyLinkedList(array[i], list); |
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* return list; |
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* } |
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* |
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* {@literal @Override} |
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* public Object toOpenValue(Object javaValue) throws OpenDataException { |
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* ArrayList<String> array = new ArrayList<String>(); |
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* for (MyLinkedList list = (MyLinkedList) javaValue; list != null; |
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* list = list.getNext()) |
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* array.add(list.getName()); |
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* return array.toArray(new String[0]); |
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* } |
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* } |
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* </pre> |
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* |
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* <p>The call to the superclass constructor specifies what the |
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* original Java type is ({@code MyLinkedList.class}) and what Open |
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* Type it is mapped to ({@code |
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* ArrayType.getArrayType(SimpleType.STRING)}). The {@code |
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* fromOpenValue} method says how we go from the Open Type ({@code |
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* String[]}) to the Java type ({@code MyLinkedList}), and the {@code |
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* toOpenValue} method says how we go from the Java type to the Open |
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* Type.</p> |
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* |
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* <p>With this mapping defined, we can annotate the {@code MyLinkedList} |
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* class appropriately:</p> |
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* |
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* <pre> |
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* {@literal @MXBeanMappingClass}(MyLinkedListMapping.class) |
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* public class MyLinkedList {...} |
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* </pre> |
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* |
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* <p>Now we can use {@code MyLinkedList} in an MXBean interface and it |
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* will work.</p> |
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* |
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* <p>If we are unable to modify the {@code MyLinkedList} class, |
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* we can define an {@link MXBeanMappingFactory}. See the documentation |
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* of that class for further details.</p> |
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2cc4873fa29f
6734273: Minor updates to documentation of Custom MXBean Mappings
emcmanus
parents:
715
diff
changeset
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* |
2cc4873fa29f
6734273: Minor updates to documentation of Custom MXBean Mappings
emcmanus
parents:
715
diff
changeset
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* @see <a href="../MXBean.html#custom">MXBean specification, section |
2cc4873fa29f
6734273: Minor updates to documentation of Custom MXBean Mappings
emcmanus
parents:
715
diff
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* "Custom MXBean type mappings"</a> |
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*/ |
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public abstract class MXBeanMapping { |
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private final Type javaType; |
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private final OpenType<?> openType; |
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private final Class<?> openClass; |
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/** |
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* <p>Construct a mapping between the given Java type and the given |
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* Open Type.</p> |
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* |
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* @param javaType the Java type (for example, {@code MyLinkedList}). |
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* @param openType the Open Type (for example, {@code |
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* ArrayType.getArrayType(SimpleType.STRING)}) |
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* |
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* @throws NullPointerException if either argument is null. |
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*/ |
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protected MXBeanMapping(Type javaType, OpenType<?> openType) { |
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if (javaType == null || openType == null) |
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throw new NullPointerException("Null argument"); |
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this.javaType = javaType; |
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this.openType = openType; |
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this.openClass = makeOpenClass(javaType, openType); |
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} |
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/** |
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* <p>The Java type that was supplied to the constructor.</p> |
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* @return the Java type that was supplied to the constructor. |
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*/ |
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public final Type getJavaType() { |
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return javaType; |
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} |
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/** |
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* <p>The Open Type that was supplied to the constructor.</p> |
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* @return the Open Type that was supplied to the constructor. |
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*/ |
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public final OpenType<?> getOpenType() { |
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return openType; |
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} |
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/** |
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* <p>The Java class that corresponds to instances of the |
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* {@linkplain #getOpenType() Open Type} for this mapping.</p> |
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* @return the Java class that corresponds to instances of the |
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* Open Type for this mapping. |
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* @see OpenType#getClassName |
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*/ |
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public final Class<?> getOpenClass() { |
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return openClass; |
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} |
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private static Class<?> makeOpenClass(Type javaType, OpenType<?> openType) { |
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if (javaType instanceof Class<?> && ((Class<?>) javaType).isPrimitive()) |
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return (Class<?>) javaType; |
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try { |
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String className = openType.getClassName(); |
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7193339: Prepare system classes be defined by a non-null module loader
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return Class.forName(className, false, MXBeanMapping.class.getClassLoader()); |
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} catch (ClassNotFoundException e) { |
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throw new RuntimeException(e); // should not happen |
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} |
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} |
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/** |
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* <p>Convert an instance of the Open Type into the Java type. |
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* @param openValue the value to be converted. |
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* @return the converted value. |
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* @throws InvalidObjectException if the value cannot be converted. |
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*/ |
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public abstract Object fromOpenValue(Object openValue) |
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throws InvalidObjectException; |
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/** |
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* <p>Convert an instance of the Java type into the Open Type. |
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* @param javaValue the value to be converted. |
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* @return the converted value. |
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* @throws OpenDataException if the value cannot be converted. |
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*/ |
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public abstract Object toOpenValue(Object javaValue) |
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throws OpenDataException; |
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/** |
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* <p>Throw an appropriate InvalidObjectException if we will not |
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* be able to convert back from the open data to the original Java |
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* object. The {@link #fromOpenValue fromOpenValue} throws an |
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* exception if a given open data value cannot be converted. This |
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* method throws an exception if <em>no</em> open data values can |
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* be converted. The default implementation of this method never |
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* throws an exception. Subclasses can override it as |
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* appropriate.</p> |
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* @throws InvalidObjectException if {@code fromOpenValue} will throw |
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* an exception no matter what its argument is. |
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*/ |
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public void checkReconstructible() throws InvalidObjectException {} |
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} |