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| − | {{EclipseLink_UserGuide
| + | '''[[Image:Elug_draft_icon.png|Warning]] This page is obsolete. Please see ''[http://www.eclipse.org/eclipselink/documentation/2.4/ Developing JAXB Applications Using EclipseLink MOXy]'' for current information.''' |
| − | |info=y
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| − | |api=y
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| − | |apis=* [http://www.eclipse.org/eclipselink/api/latest/org/eclipse/persistence/mappings/XmlElementRef.html XmlElementRef]
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| − | * [http://www.eclipse.org/eclipselink/api/latest/org/eclipse/persistence/mappings/XXmlRootElement.html XXmlRootElement]
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| − | }}
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| − | =Substitution Groups =
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| − | With JAXB, you can use the element ''name'', instead of using the '''xsi:type''' attribute, to represent inheritance by using XML schema '''substitution groups'''. JAXB leverages existing XML schema concepts to produce very portable XML documents.
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| − | In this example, the Java model contains an abstract superclass for all types of contact information:
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| − | <source lang="Java">
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| − | package blog.inheritance;
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| − | public abstract class ContactInfo {
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| − | }
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| − | </source>
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| − | The '''Address''' and '''PhoneNumber''' classes are the concrete implementations of '''ContactInfo'''. Both classes use the '''@XmlRootElement''' annotation because the element name is used as the inheritance indicator.
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| − | <source lang="Java">
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| − | package blog.inheritance;
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| − | import javax.xml.bind.annotation.XmlRootElement;
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| − | @XmlRootElement
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| − | public class Address extends ContactInfo {
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| − |
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| − | private String street;
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| − | public String getStreet() {
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| − | return street;
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| − | }
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| − | public void setStreet(String street) {
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| − | this.street = street;
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| − | }
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| − | }
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| − | @XmlRootElement
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| − | public class PhoneNumber extends ContactInfo {
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| − |
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| − | }
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| − | </source>
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| − | Because the '''Customer''' object can have different types of contact information, the property refers to the superclass. The '''contactInfo''' property contains the '''@XmlElementRef''' annotation to specify that the value type will be derived from the element name (and namespace URI).
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| − | <source lang="Java">
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| − | package blog.inheritance;
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| − |
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| − | import javax.xml.bind.annotation.XmlElementRef;
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| − | import javax.xml.bind.annotation.XmlRootElement;
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| − |
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| − | @XmlRootElement
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| − | public class Customer {
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| − |
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| − | private ContactInfo contactInfo;
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| − |
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| − | @XmlElementRef
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| − | public ContactInfo getContactInfo() {
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| − | return contactInfo;
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| − | }
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| − |
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| − | public void setContactInfo(ContactInfo contactInfo) {
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| − | this.contactInfo = contactInfo;
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| − | }
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| − |
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| − | }
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| − | </source>
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| − | This schema represents the JAXB view of the object model. The schema type inheritance matches the Java class inheritance.
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| − | <source lang="xml">
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| − | <xs:schema version="1.0" xmlns:xs="http://www.w3.org/2001/XMLSchema">
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| − |
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| − | <xs:element name="customer" type="customer"/>
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| − |
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| − | <xs:element name="contactInfo" type="contactInfo"/>
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| − |
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| − | <xs:element name="address" type="address"
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| − | substitutionGroup="contactInfo"/>
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| − |
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| − | <xs:element name="phoneNumber" type="phoneNumber"
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| − | substitutionGroup="contactInfo"/>
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| − |
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| − | <xs:complexType name="customer">
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| − | <xs:sequence>
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| − | <xs:element ref="contactInfo"/>
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| − | </xs:sequence>
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| − | </xs:complexType>
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| − |
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| − | <xs:complexType name="contactInfo" abstract="true">
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| − | <xs:sequence/>
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| − | </xs:complexType>
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| − |
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| − | <xs:complexType name="address">
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| − | <xs:complexContent>
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| − | <xs:extension base="contactInfo">
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| − | <xs:sequence>
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| − | <xs:element name="street" type="xs:string" minOccurs="0"/>
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| − | </xs:sequence>
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| − | </xs:extension>
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| − | </xs:complexContent>
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| − | </xs:complexType>
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| − |
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| − | <xs:complexType name="phoneNumber">
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| − | <xs:complexContent>
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| − | <xs:extension base="contactInfo">
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| − | <xs:sequence/>
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| − | </xs:extension>
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| − | </xs:complexContent>
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| − | </xs:complexType>
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| − |
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| − | </xs:schema>
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| − | | + | |
| − | </source>
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| − | Notice that each '''type''' has a corresponding global element. Additionally, the '''address''' and '''phoneNumber''' elements may be substituted for the '''contactInfo''' element.
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| − | ==Example ==
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| − | This example code demonstrates using the '''xsi:type''' attribute to represent inheritance:
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| − | <source lang="Java">
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| − | package blog.inheritance;
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| − |
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| − | import javax.xml.bind.JAXBContext;
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| − | import javax.xml.bind.Marshaller;
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| − |
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| − | public class Demo {
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| − |
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| − | public static void main(String[] args) throws Exception {
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| − | Customer customer = new Customer();
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| − | Address address = new Address();
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| − | address.setStreet("1 A Street");
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| − | customer.setContactInfo(address);
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| − |
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| − | JAXBContext jc = JAXBContext.newInstance(Customer.class, Address.class, PhoneNumber.class);
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| − |
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| − | Marshaller marshaller = jc.createMarshaller();
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| − | marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
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| − | marshaller.marshal(customer, System.out);
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| − | }
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| − |
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| − | }
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| − | The example produces the following XML:
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| − | <source lang="xml">
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| − |
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| − | <customer>
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| − | <address>
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| − | <street>1 A Street</street>
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| − | </address>
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| − | </customer>
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| − | </source>
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| − | Notice that the '''Address''' object is marshalled to the '''address''' element.
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| − | {{EclipseLink_MOXy
| + | |
| − | |previous=[[EclipseLink/UserGuide/MOXy/Advanced_XML_Schema_Concepts/Handling_Null_Values|Handling Null Values]]
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| − | |next =[[EclipseLink/UserGuide/MOXy/Advanced_XML_Schema_Concepts/Wildcard_Content|Wildcard Content]]
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| − | |up =[[EclipseLink/UserGuide/MOXy/Advanced XML Schema Concepts|Advanced XML Schema Concepts]]
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| − | |version=2.2.0
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| − | }}
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This page is obsolete. Please see Developing JAXB Applications Using EclipseLink MOXy for current information.