1 /* 2 * Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package javax.xml.bind; 27 28 import javax.xml.namespace.QName; 29 import java.io.Serializable; 30 31 /** 32 * <p>JAXB representation of an Xml Element.</p> 33 * 34 * <p>This class represents information about an Xml Element from both the element 35 * declaration within a schema and the element instance value within an xml document 36 * with the following properties 37 * <ul> 38 * <li>element's xml tag <b><tt>name</tt></b></li> 39 * <li><b><tt>value</tt></b> represents the element instance's atttribute(s) and content model</li> 40 * <li>element declaration's <b><tt>declaredType</tt></b> (<tt>xs:element @type</tt> attribute)</li> 41 * <li><b><tt>scope</tt></b> of element declaration</li> 42 * <li>boolean <b><tt>nil</tt></b> property. (element instance's <tt><b>xsi:nil</b></tt> attribute)</li> 43 * </ul> 44 * 45 * <p>The <tt>declaredType</tt> and <tt>scope</tt> property are the 46 * JAXB class binding for the xml type definition. 47 * </p> 48 * 49 * <p><b><tt>Scope</tt></b> is either {@link GlobalScope} or the Java class representing the 50 * complex type definition containing the schema element declaration. 51 * </p> 52 * 53 * <p>There is a property constraint that if <b><tt>value</tt></b> is <tt>null</tt>, 54 * then <tt>nil</tt> must be <tt>true</tt>. The converse is not true to enable 55 * representing a nil element with attribute(s). If <tt>nil</tt> is true, it is possible 56 * that <tt>value</tt> is non-null so it can hold the value of the attributes 57 * associated with a nil element. 58 * </p> 59 * 60 * @author Kohsuke Kawaguchi, Joe Fialli 61 * @since JAXB 2.0 62 */ 63 64 public class JAXBElement<T> implements Serializable { 65 66 /** xml element tag name */ 67 final protected QName name; 68 69 /** Java datatype binding for xml element declaration's type. */ 70 final protected Class<T> declaredType; 71 72 /** Scope of xml element declaration representing this xml element instance. 73 * Can be one of the following values: 74 * - {@link GlobalScope} for global xml element declaration. 75 * - local element declaration has a scope set to the Java class 76 * representation of complex type defintion containing 77 * xml element declaration. 78 */ 79 final protected Class scope; 80 81 /** xml element value. 82 Represents content model and attributes of an xml element instance. */ 83 protected T value; 84 85 /** true iff the xml element instance has xsi:nil="true". */ 86 protected boolean nil = false; 87 88 /** 89 * Designates global scope for an xml element. 90 */ 91 public static final class GlobalScope {} 92 93 /** 94 * <p>Construct an xml element instance.</p> 95 * 96 * @param name Java binding of xml element tag name 97 * @param declaredType Java binding of xml element declaration's type 98 * @param scope 99 * Java binding of scope of xml element declaration. 100 * Passing null is the same as passing <tt>GlobalScope.class</tt> 101 * @param value 102 * Java instance representing xml element's value. 103 * @see #getScope() 104 * @see #isTypeSubstituted() 105 */ 106 public JAXBElement(QName name, 107 Class<T> declaredType, 108 Class scope, 109 T value) { 110 if(declaredType==null || name==null) 111 throw new IllegalArgumentException(); 112 this.declaredType = declaredType; 113 if(scope==null) scope = GlobalScope.class; 114 this.scope = scope; 115 this.name = name; 116 setValue(value); 117 } 118 119 /** 120 * Construct an xml element instance. 121 * 122 * This is just a convenience method for <tt>new JAXBElement(name,declaredType,GlobalScope.class,value)</tt> 123 */ 124 public JAXBElement(QName name, Class<T> declaredType, T value ) { 125 this(name,declaredType,GlobalScope.class,value); 126 } 127 128 /** 129 * Returns the Java binding of the xml element declaration's type attribute. 130 */ 131 public Class<T> getDeclaredType() { 132 return declaredType; 133 } 134 135 /** 136 * Returns the xml element tag name. 137 */ 138 public QName getName() { 139 return name; 140 } 141 142 /** 143 * <p>Set the content model and attributes of this xml element.</p> 144 * 145 * <p>When this property is set to <tt>null</tt>, <tt>isNil()</tt> must by <tt>true</tt>. 146 * Details of constraint are described at {@link #isNil()}.</p> 147 * 148 * @see #isTypeSubstituted() 149 */ 150 public void setValue(T t) { 151 this.value = t; 152 } 153 154 /** 155 * <p>Return the content model and attribute values for this element.</p> 156 * 157 * <p>See {@link #isNil()} for a description of a property constraint when 158 * this value is <tt>null</tt></p> 159 */ 160 public T getValue() { 161 return value; 162 } 163 164 /** 165 * Returns scope of xml element declaration. 166 * 167 * @see #isGlobalScope() 168 * @return <tt>GlobalScope.class</tt> if this element is of global scope. 169 */ 170 public Class getScope() { 171 return scope; 172 } 173 174 /** 175 * <p>Returns <tt>true</tt> iff this element instance content model 176 * is nil.</p> 177 * 178 * <p>This property always returns <tt>true</tt> when {@link #getValue()} is null. 179 * Note that the converse is not true, when this property is <tt>true</tt>, 180 * {@link #getValue()} can contain a non-null value for attribute(s). It is 181 * valid for a nil xml element to have attribute(s).</p> 182 */ 183 public boolean isNil() { 184 return (value == null) || nil; 185 } 186 187 /** 188 * <p>Set whether this element has nil content.</p> 189 * 190 * @see #isNil() 191 */ 192 public void setNil(boolean value) { 193 this.nil = value; 194 } 195 196 /* Convenience methods 197 * (Not necessary but they do unambiguously conceptualize 198 * the rationale behind this class' fields.) 199 */ 200 201 /** 202 * Returns true iff this xml element declaration is global. 203 */ 204 public boolean isGlobalScope() { 205 return this.scope == GlobalScope.class; 206 } 207 208 /** 209 * Returns true iff this xml element instance's value has a different 210 * type than xml element declaration's declared type. 211 */ 212 public boolean isTypeSubstituted() { 213 if(value==null) return false; 214 return value.getClass() != declaredType; 215 } 216 217 private static final long serialVersionUID = 1L; 218 }