XmlElementDecl (Java EE 5 SDK)

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摘要: REQUIRED | OPTIONAL	详细信息: ELEMENT

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javax.xml.bind.annotation Annotation Type XmlElementDecl

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@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</foo>

     // Example: code fragment corresponding to XML input
     JAXBElement<string> o =
     (JAXBElement</string><string>)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">
 </xs:element></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><xs:element name="bar" type="xs:string">
         </xs:element></xs:choice>
       </xs:complextype> 
       <xs:element name="foo" type="xs:int">
     </xs:element></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".

从以下版本开始:

JAXB 2.0

另请参见:

XmlRegistry

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Required Element Summary
String	name           local name of the XML element.

 

Optional Element Summary
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.

 

元素详细信息

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.

另请参见:

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.

默认值:

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

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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.

另请参见:

name()

默认值:

"##default"

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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.

另请参见:

substitutionHeadName()

默认值:

"##default"

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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.

另请参见:

substitutionHeadNamespace()

默认值:

""

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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.

默认值:

"\u0000"

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概述  软件包   类  树  已过时  索引  帮助		Java EE 5 SDK 深圳电信培训中心.徐海蛟老师.
上一个类   下一个类	框架    无框架
摘要: REQUIRED | OPTIONAL	详细信息: ELEMENT

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