Annotation Type XmlElementDecl


@Retention(value=RUNTIME)
 @Target(value=METHOD)
public @interface XmlElementDecl

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 XmlRegistry.
  • The element factory method must take one parameter assignable to Object.

Example 1: Annotation on a factory method 

// Example: code fragment
     @XmlRegistry
     class ObjectFactory {
         @XmlElementDecl(name="foo")
         JAXBElement<String> createFoo(String s) { ... }
     }
<!-- XML input -->
       <foo>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: XML schema definition -->
     <xs:element name="foo" type="xs: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. 

<!-- Example: XML schema definition -->
     <xs:schema>
       <xs:complexType name="pea">
         <xs:choice maxOccurs="unbounded">
           <xs:element name="foo" type="xs:string"/>
           <xs:element name="bar" type="xs:string"/>
         </xs:choice>
       </xs:complexType>
       <xs:element name="foo" type="xs:int"/>
     </xs:schema>
// 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 createPeaFoo(String s);

         @XmlElementDecl(scope=Pea.class,name="bar")
         JAXBElement createPeaBar(String s);

         @XmlElementDecl(name="foo")
         JAXBElement 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".
Since:
JAXB 2.0
See Also:
XmlRegistry

Required Elements

Modifier and Type Required Element and Description
String name

local name of the XML element.

Optional Elements

Modifier and Type Optional Element and Description
String defaultValue

Default value of this element.
String namespace

namespace name of the XML element.
Class scope

scope of the mapping.
String substitutionHeadName

XML local name of a substitution group's head element.
String substitutionHeadNamespace

namespace name of a substitution group's head XML element.

Elements

name

public abstract String name

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 Also:
namespace()

scope

public abstract Class scope

scope of the mapping.

If this is not XmlElementDecl.GLOBAL, then this element declaration mapping is only active within the specified class.

Default:
javax.xml.bind.annotation.XmlElementDecl.GLOBAL.class

namespace

public abstract String namespace

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 Also:
name()
Default:
"##default"

substitutionHeadNamespace

public abstract String substitutionHeadNamespace

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 substitutionHeadName().

If 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 susbstitutionHeadName() is "".

If 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 XmlRegistry, is mapped.

If susbtitutionHeadName() is not "" and the value is not "##default", then the value is the namespace name.

See Also:
substitutionHeadName()
Default:
"##default"

substitutionHeadName

public abstract String substitutionHeadName

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 Also:
substitutionHeadNamespace()
Default:
""

defaultValue

public abstract String defaultValue

Default value of this element.

The 

' '
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.
Default:
"\u0000"

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https://docs.oracle.com/javase/8/docs/api/javax/xml/bind/annotation/XmlElementDecl.html