XmlRootElement (Java EE 5)

用法

@XmlRootElement 注释可以与以下程序元素一起使用：

• 顶层类
• 枚举类型

有关其他公共信息，请参阅 javax.xml.bind.package javadoc 中的“包规范”。

当使用 @XmlRootElement 注释对顶层类或枚举类型进行注释时，类型值被表示为 XML 文档中的 XML 元素。

此注释可与以下注释一起使用： XmlType、XmlEnum、XmlAccessorType、 XmlAccessorOrder。

示例 1：将元素与 XML 模式类型关联

     // 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 </x>
       <y> 5 </y>
     </point>
 

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

示例 2：类型继承的正交性

某一类型上注释的元素声明不会被其派生类型继承。以下示例显示了这一点：

     // 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: 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>
 

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 </x>
       <y> 5 </y>
     </point>
 

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

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: 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>
 

Since:

JAXB2.0

Author:

Sekhar Vajjhala, Sun Microsystems, Inc.

abstract public String namespace()
XML 元素的名称空间名。

如果该值为 "##default"，那么 XML 名称空间名派生于类 (XmlSchema) 的包。如果没有对包命名，那么 XML 名称空间是默认的空名称空间。

英文文档：

namespace

public abstract String namespace

namespace name of the XML element.

If the value is "##default", then the XML namespace name is derived from the package of the class ( XmlSchema ). If the package is unnamed, then the XML namespace is the default empty namespace.

Default:

"##default"

abstract public String name()
XML 元素的本地名称。

如果值为 "##default"，则名称派生于类名称。

英文文档：

name

public abstract String name

local name of the XML element.

If the value is "##default", then the name is derived from the class name.

Default:

"##default"

Copyright 2007 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.