001/*
002 * Version.java July 2008
003 *
004 * Copyright (C) 2008, Niall Gallagher <niallg@users.sf.net>
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 
015 * implied. See the License for the specific language governing 
016 * permissions and limitations under the License.
017 */
018
019package org.simpleframework.xml;
020
021import java.lang.annotation.Retention;
022import java.lang.annotation.RetentionPolicy;
023
024/**
025 * The <code>Version</code> annotation is used to specify an attribute
026 * that is used to represent a revision of the class XML schema. This
027 * annotation can annotate only floating point types such as double, 
028 * float, and the java primitive object types. This can not be used to
029 * annotate strings, enumerations or other primitive types.
030 * 
031 * @author Niall Gallagher
032 */
033@Retention(RetentionPolicy.RUNTIME)
034public @interface Version {
035   
036   /**
037    * This represents the name of the XML attribute. Annotated fields
038    * or methods can optionally provide the name of the XML attribute
039    * they represent. If a name is not provided then the field or 
040    * method name is used in its place. A name can be specified if 
041    * the field or method name is not suitable for the XML attribute.
042    * 
043    * @return the name of the XML attribute this represents
044    */
045   String name() default "";
046
047   /**
048    * This represents the revision of the class. A revision is used
049    * by the deserialization process to determine how to match the
050    * annotated fields and methods to the XML elements and attributes.
051    * If the version deserialized is different to the annotated 
052    * revision then annotated fields and methods are not required 
053    * and if there are excessive XML nodes they are ignored.
054    * 
055    * @return this returns the version of the XML class schema
056    */
057   double revision() default 1.0;
058   
059   /**
060    * Determines whether the version is required within an XML
061    * element. Any field marked as not required will not have its
062    * value set when the object is deserialized. This is written
063    * only if the version is not the same as the default version.
064    * 
065    * @return true if the version is required, false otherwise
066    */
067   boolean required() default false;
068}