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/* * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.xml.bind; import javax.xml.namespace.QName; import java.io.Serializable; /** * <p>JAXB representation of an Xml Element.</p> * * <p>This class represents information about an Xml Element from both the element * declaration within a schema and the element instance value within an xml document * with the following properties * <ul> * <li>element's xml tag <b><tt>name</tt></b></li> * <li><b><tt>value</tt></b> represents the element instance's atttribute(s) and content model</li> * <li>element declaration's <b><tt>declaredType</tt></b> (<tt>xs:element @type</tt> attribute)</li> * <li><b><tt>scope</tt></b> of element declaration</li> * <li>boolean <b><tt>nil</tt></b> property. (element instance's <tt><b>xsi:nil</b></tt> attribute)</li> * </ul> * * <p>The <tt>declaredType</tt> and <tt>scope</tt> property are the * JAXB class binding for the xml type definition. * </p> * * <p><b><tt>Scope</tt></b> is either {@link GlobalScope} or the Java class representing the * complex type definition containing the schema element declaration. * </p> * * <p>There is a property constraint that if <b><tt>value</tt></b> is <tt>null</tt>, * then <tt>nil</tt> must be <tt>true</tt>. The converse is not true to enable * representing a nil element with attribute(s). If <tt>nil</tt> is true, it is possible * that <tt>value</tt> is non-null so it can hold the value of the attributes * associated with a nil element. * </p> * * @author Kohsuke Kawaguchi, Joe Fialli * @since JAXB 2.0 */ public class JAXBElement<T> implements Serializable { /** xml element tag name */ final protected QName name; /** Java datatype binding for xml element declaration's type. */ final protected Class<T> declaredType; /** Scope of xml element declaration representing this xml element instance. * Can be one of the following values: * - {@link GlobalScope} for global xml element declaration. * - local element declaration has a scope set to the Java class * representation of complex type defintion containing * xml element declaration. */ final protected Class scope; /** xml element value. Represents content model and attributes of an xml element instance. */ protected T value; /** true iff the xml element instance has xsi:nil="true". */ protected boolean nil = false; /** * Designates global scope for an xml element. */ public static final class GlobalScope {} /** * <p>Construct an xml element instance.</p> * * @param name Java binding of xml element tag name * @param declaredType Java binding of xml element declaration's type * @param scope * Java binding of scope of xml element declaration. * Passing null is the same as passing <tt>GlobalScope.class</tt> * @param value * Java instance representing xml element's value. * @see #getScope() * @see #isTypeSubstituted() */ public JAXBElement(QName name, Class<T> declaredType, Class scope, T value) { if(declaredType==null || name==null) throw new IllegalArgumentException(); this.declaredType = declaredType; if(scope==null) scope = GlobalScope.class; this.scope = scope; this.name = name; setValue(value); } /** * Construct an xml element instance. * * This is just a convenience method for <tt>new JAXBElement(name,declaredType,GlobalScope.class,value)</tt> */ public JAXBElement(QName name, Class<T> declaredType, T value ) { this(name,declaredType,GlobalScope.class,value); } /** * Returns the Java binding of the xml element declaration's type attribute. */ public Class<T> getDeclaredType() { return declaredType; } /** * Returns the xml element tag name. */ public QName getName() { return name; } /** * <p>Set the content model and attributes of this xml element.</p> * * <p>When this property is set to <tt>null</tt>, <tt>isNil()</tt> must by <tt>true</tt>. * Details of constraint are described at {@link #isNil()}.</p> * * @see #isTypeSubstituted() */ public void setValue(T t) { this.value = t; } /** * <p>Return the content model and attribute values for this element.</p> * * <p>See {@link #isNil()} for a description of a property constraint when * this value is <tt>null</tt></p> */ public T getValue() { return value; } /** * Returns scope of xml element declaration. * * @see #isGlobalScope() * @return <tt>GlobalScope.class</tt> if this element is of global scope. */ public Class getScope() { return scope; } /** * <p>Returns <tt>true</tt> iff this element instance content model * is nil.</p> * * <p>This property always returns <tt>true</tt> when {@link #getValue()} is null. * Note that the converse is not true, when this property is <tt>true</tt>, * {@link #getValue()} can contain a non-null value for attribute(s). It is * valid for a nil xml element to have attribute(s).</p> */ public boolean isNil() { return (value == null) || nil; } /** * <p>Set whether this element has nil content.</p> * * @see #isNil() */ public void setNil(boolean value) { this.nil = value; } /* Convenience methods * (Not necessary but they do unambiguously conceptualize * the rationale behind this class' fields.) */ /** * Returns true iff this xml element declaration is global. */ public boolean isGlobalScope() { return this.scope == GlobalScope.class; } /** * Returns true iff this xml element instance's value has a different * type than xml element declaration's declared type. */ public boolean isTypeSubstituted() { if(value==null) return false; return value.getClass() != declaredType; } private static final long serialVersionUID = 1L; }