jakarta.xml.bind.annotation.XmlElementDecl Maven / Gradle / Ivy
/*
* Copyright (c) 2004, 2021 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package jakarta.xml.bind.annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static java.lang.annotation.ElementType.METHOD;
/**
* Maps a factory method to a XML element.
*
* Usage
*
* The annotation creates a mapping between an XML schema element
* declaration and a element factory method that returns a
* JAXBElement instance representing the element
* declaration. Typically, the element factory method is generated
* (and annotated) from a schema into the ObjectFactory class in a
* Java package that represents the binding of the element
* declaration's target namespace. Thus, while the annotation syntax
* allows @XmlElementDecl to be used on any method, semantically
* its use is restricted to annotation of element factory method.
*
* The usage is subject to the following constraints:
*
*
* - The class containing the element factory method annotated
* with @XmlElementDecl must be marked with {@link
* XmlRegistry}.
* - The element factory method must take one parameter
* assignable to {@link Object}.
*
*
* Example 1: Annotation on a factory method
*
* // Example: code fragment
* @XmlRegistry
* class ObjectFactory {
* @XmlElementDecl(name="foo")
* JAXBElement<String> createFoo(String s) { ... }
* }
*
* {@code
*
*
* string
*
* // Example: code fragment corresponding to XML input
* JAXBElement o =
* (JAXBElement)unmarshaller.unmarshal(aboveDocument);
* // print JAXBElement instance to show values
* System.out.println(o.getName()); // prints "{}foo"
* System.out.println(o.getValue()); // prints "string"
* System.out.println(o.getValue().getClass()); // prints "java.lang.String"
*
*
*
*
* Example 2: Element declaration with non local scope
*
* The following example illustrates the use of scope annotation
* parameter in binding of element declaration in schema derived
* code.
*
* The following example may be replaced in a future revision of
* this javadoc.
*
*
{@code
*
*
*
*
*
*
*
* }
*
* // Example: expected default binding
* class Pea {
* @XmlElementRefs({
* @XmlElementRef(name="foo",type=JAXBElement.class)
* @XmlElementRef(name="bar",type=JAXBElement.class)
* })
* List<JAXBElement<String>> fooOrBar;
* }
*
* @XmlRegistry
* class ObjectFactory {
* @XmlElementDecl(scope=Pea.class,name="foo")
* JAXBElement<String> createPeaFoo(String s);
*
* @XmlElementDecl(scope=Pea.class,name="bar")
* JAXBElement<String> createPeaBar(String s);
*
* @XmlElementDecl(name="foo")
* JAXBElement<Integer> createFoo(Integer i);
* }
*
*
* Without scope createFoo and createPeaFoo would become ambiguous
* since both of them map to a XML schema element with the same local
* name "foo".
*
* @see XmlRegistry
* @since 1.6, JAXB 2.0
*/
@Retention(RUNTIME)
@Target({METHOD})
public @interface XmlElementDecl {
/**
* scope of the mapping.
*
*
* If this is not {@link XmlElementDecl.GLOBAL}, then this element
* declaration mapping is only active within the specified class.
*/
Class scope() default GLOBAL.class;
/**
* namespace name of the XML element.
*
* If the value is "##default", then the value is the namespace
* name for the package of the class containing this factory method.
*
* @see #name()
*/
String namespace() default "##default";
/**
* local name of the XML element.
*
*
* Note to reviewers: There is no default name; since
* the annotation is on a factory method, it is not clear that the
* method name can be derived from the factory method name.
* @see #namespace()
*/
String name();
/**
* namespace name of a substitution group's head XML element.
*
* This specifies the namespace name of the XML element whose local
* name is specified by {@code substitutionHeadName()}.
*
* If {@code susbtitutionHeadName()} is "", then this
* value can only be "##default". But the value is ignored since
* since this element is not part of susbtitution group when the
* value of {@code susbstitutionHeadName()} is "".
*
* If {@code susbtitutionHeadName()} is not "" and the value is
* "##default", then the namespace name is the namespace name to
* which the package of the containing class, marked with {@link
* XmlRegistry }, is mapped.
*
* If {@code susbtitutionHeadName()} is not "" and the value is
* not "##default", then the value is the namespace name.
*
* @see #substitutionHeadName()
*/
String substitutionHeadNamespace() default "##default";
/**
* XML local name of a substitution group's head element.
*
* If the value is "", then this element is not part of any
* substitution group.
*
* @see #substitutionHeadNamespace()
*/
String substitutionHeadName() default "";
/**
* Default value of this element.
*
*
* The
'\u0000'
value specified as a default of this annotation element
* is used as a poor-man's substitute for null to allow implementations
* to recognize the 'no default value' state.
*/
String defaultValue() default "\u0000";
/**
* Used in {@link XmlElementDecl#scope()} to
* signal that the declaration is in the global scope.
*/
final class GLOBAL {
private GLOBAL() {}
}
}