Java javax.xml.bind.annotation Annotation Type XmlRootElement（JDK8）

@Retention(value=RUNTIME)
 @Target(value=TYPE)
public @interface XmlRootElement

Maps a class or an enum type to an XML element.

Usage

The @XmlRootElement annotation can be used with the following program elements:

• a top level class
• an enum type

See "Package Specification" in javax.xml.bind.package javadoc for additional common information.

When a top level class or an enum type is annotated with the @XmlRootElement annotation, then its value is represented as XML element in an XML document.

This annotation can be used with the following annotations: XmlType, XmlEnum, XmlAccessorType, XmlAccessorOrder.

Example 1: Associate an element with XML Schema type

     // Example: Code fragment
     @XmlRootElement
     class Point {
        int x;
        int y;
        Point(int _x,int _y) {x=_x;y=_y;}
     }
 

     //Example: Code fragment corresponding to XML output
     marshal( new Point(3,5), System.out);
 

     <!-- Example: XML output -->
     <point>
       <x> 3 
       <y> 5 
     </point>
 

The annotation causes an global element declaration to be produced in the schema. The global element declaration is associated with the XML schema type to which the class is mapped.

     <!-- Example: XML schema definition -->
     <xs:element name="point" type="point"/>
     <xs:complexType name="point">
       <xs:sequence>
         <xs:element name="x" type="xs:int"/>
         <xs:element name="y" type="xs:int"/>
       </xs:sequence>
     </xs:complexType>
 

Example 2: Orthogonality to type inheritance

An element declaration annotated on a type is not inherited by its derived types. The following example shows this.

     // Example: Code fragment
     @XmlRootElement
     class Point3D extends Point {
         int z;
         Point3D(int _x,int _y,int _z) {super(_x,_y);z=_z;}
     }

     //Example: Code fragment corresponding to XML output *
     marshal( new Point3D(3,5,0), System.out );

     <!-- Example: XML output -->
     <!-- The element name is point3D not point -->
     <point3D>
       <x>3</x>
       <y>5</y>
       <z>0</z>
     </point3D>

     <!-- Example: XML schema definition -->
     <xs:element name="point3D" type="point3D"/>
     <xs:complexType name="point3D">
       <xs:complexContent>
         <xs:extension base="point">
           <xs:sequence>
             <xs:element name="z" type="xs:int"/>
           </xs:sequence>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
 

Example 3: Associate a global element with XML Schema type to which the class is mapped.

     //Example: Code fragment
     @XmlRootElement(name="PriceElement")
     public class USPrice {
         @XmlElement
         public java.math.BigDecimal price;
     }

     <!-- Example: XML schema definition -->
     <xs:element name="PriceElement" type="USPrice"/>
     <xs:complexType name="USPrice">
       <xs:sequence>
         <xs:element name="price" type="xs:decimal"/>
       </sequence>
     </xs:complexType>