001/*
002 * Text.java April 2007
003 *
004 * Copyright (C) 2007, 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.RetentionPolicy;
022import java.lang.annotation.Retention;
023
024/**
025 * The <code>Text</code> annotation is used to represent a field or
026 * method that appears as text within an XML element. Methods and
027 * fields annotated with this must represent primitive values, which
028 * means that the type is converted to and from an XML representation
029 * using a <code>Transform</code> object. For example, the primitive 
030 * types typically annotated could be strings, integers, or dates.  
031 * <p>
032 * One restriction on this annotation is that it can only appear once 
033 * within a schema class, and it can not appear with the another XML 
034 * element annotations, such as the <code>Element</code> annotation. 
035 * It can however appear with any number of <code>Attribute</code> 
036 * annotations.
037 * <pre>
038 * 
039 *    &lt;example one="value" two="value"&gt;
040 *       Example text value       
041 *    &lt;/example&gt;
042 * 
043 * </pre>
044 * Text values are used when an element containing attributes is
045 * used to wrap a text value with no child elements. This can be
046 * used in place of an element annotation to represent a primitive
047 * which is wrapped in a surrounding XML element.
048 * 
049 * @author Niall Gallagher
050 * 
051 * @see org.simpleframework.xml.transform.Transformer
052 */ 
053@Retention(RetentionPolicy.RUNTIME)
054public @interface Text {
055   
056   /**
057    * This is used to provide a default value for the text data if
058    * the annotated field or method is null. This ensures the the
059    * serialization process writes the text data with a value even
060    * if the value is null, and allows deserialization to determine
061    * whether the value within the object was null or not.
062    * 
063    * @return this returns the default attribute value to use
064    */
065   String empty() default "";
066   
067   /**
068    * This is used to determine whether the text is written within 
069    * CDATA block or not. If this is set to true then the text is
070    * written within a CDATA block, by default the text is output
071    * as escaped XML. Typically this is used for large text values.
072    * 
073    * @return true if the data is to be wrapped in a CDATA block
074    */
075   boolean data() default false;
076   
077   /**
078    * Determines whether the text value is required within the XML
079    * document. Any field marked as not required may not have its
080    * value set when the object is deserialized. If an object is to
081    * be serialized only a null attribute will not appear in XML.
082    * 
083    * @return true if the element is required, false otherwise
084    */
085   boolean required() default true; 
086}