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javax.xml.bind.annotation Annotation Type XmlIDREF
@Target(value={FIELD, METHOD})
将 JavaBean 属性映射到 XML IDREF。
要在 XML 序列化然后反序列化这一过程中保持对象图形的引用完整性,需要通过使用引用或容器适当地对对象引用进行编组。注释 @XmlID 和 @XmlIDREF 一起使用时允许通过容器或引用来实现 JavaBean 属性类型的自定义映射。
用法
@XmlIDREF 注释能够与以下程序元素一起使用:- JavaBean 属性
- 非 static、非 transient 字段
有关其他公共消息,请参阅 javax.xml.bind.package javadoc 中的“包规范”。
用法受到以下约束的限制:
- 如果字段或属性的类型是一个 collection 类型,则集合项类型必须包含一个用 @XmlID 注释的属性或字段。
- 如果字段或属性的类型是 single valued,则属性或字段的类型必须包含一个用 @XmlID 注释的属性或字段。
注:如果集合项类型或属性的类型(用于非 collection 类型)是 java.lang.Object,则该实例必须包含一个用 @XmlID 属性注释的属性/字段。
- 此注释可与以下注释一起使用:
XmlElement
、XmlAttribute
、XmlList
和XmlElements
。
示例:将 JavaBean 属性映射到 xs:IDREF(即通过引用而不是通过包含)。
//EXAMPLE: Code fragment public class Shipping { @XmlIDREF public Customer getCustomer(); public void setCustomer(Customer customer); .... } <!-- Example: XML Schema fragment --> <xs:complexType name="Shipping"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:IDREF"/> .... </xs:sequence> </xs:complexContent> </xs:complexType>
示例 2:以下是一个对比容器与引用的完整示例。
// By default, Customer maps to complex type xs:Customer public class Customer { // map JavaBean property type to xs:ID @XmlID public String getCustomerID(); public void setCustomerID(String id); // .... other properties not shown } // By default, Invoice maps to a complex type xs:Invoice public class Invoice { // map by reference @XmlIDREF public Customer getCustomer(); public void setCustomer(Customer customer); // .... other properties not shown here } // By default, Shipping maps to complex type xs:Shipping public class Shipping { // map by reference @XmlIDREF public Customer getCustomer(); public void setCustomer(Customer customer); } // at least one class must reference Customer by containment; // Customer instances won't be marshalled. @XmlElement(name="CustomerData") public class CustomerData { // map reference to Customer by containment by default. public Customer getCustomer(); // maps reference to Shipping by containment by default. public Shipping getShipping(); // maps reference to Invoice by containment by default. public Invoice getInvoice(); } <!-- XML Schema mapping for above code frament --> <xs:complexType name="Invoice"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:IDREF"/> .... </xs:sequence> </xs:complexContent> </xs:complexType> <xs:complexType name="Shipping"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:IDREF"/> .... </xs:sequence> </xs:complexContent> </xs:complexType> <xs:complexType name="Customer"> <xs:complexContent> <xs:sequence> .... </xs:sequence> <xs:attribute name="CustomerID" type="xs:ID"/> </xs:complexContent> </xs:complexType> <xs:complexType name="CustomerData"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:Customer"/> <xs:element name="shipping" type="xs:Shipping"/> <xs:element name="invoice" type="xs:Invoice"/> </xs:sequence> </xs:complexContent> </xs:complexType> <xs:element name"customerData" type="xs:CustomerData"/> <!-- Instance document conforming to the above XML Schema --> <customerData> <customer customerID="Alice"> .... </customer> <shipping customer="Alice"> .... </shipping> <invoice customer="Alice"> .... </invoice> </customerData>
示例 3:将列表映射到 IDREF 类型的重复元素。
// Code fragment public class Shipping { @XmlIDREF @XmlElement(name="Alice") public List customers; } <!-- XML schema fragment --> <xs:complexType name="Shipping"> <xs:sequence> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element name="Alice" type="xs:IDREF"/> </xs:choice> </xs:sequence> </xs:complexType>
示例 4:将列表映射到 IDREF 类型的元素列表。
//Code fragment public class Shipping { @XmlIDREF @XmlElements( @XmlElement(name="Alice", type="Customer.class") @XmlElement(name="John", type="InternationalCustomer.class") public List customers; } <!-- XML Schema fragment --> <xs:complexType name="Shipping"> <xs:sequence> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element name="Alice" type="xs:IDREF"/> <xs:element name="John" type="xs:IDREF"/> </xs:choice> </xs:sequence> </xs:complexType>
since | JAXB2.0 | |
version |
| |
See also | javax.xml.bind.annotation.XmlID |
Maps a JavaBean property to XML IDREF.
To preserve referential integrity of an object graph across XML serialization followed by a XML deserialization, requires an object reference to be marshalled by reference or containment appropriately. Annotations @XmlID and @XmlIDREF together allow a customized mapping of a JavaBean property's type by containment or reference.
Usage
The @XmlIDREF annotation can be used with the following program elements:- a JavaBean property
- non static, non transient field
See "Package Specification" in javax.xml.bind.package javadoc for additional common information.
The usage is subject to the following constraints:
- If the type of the field or property is a collection type, then the collection item type must contain a property or field annotated with @XmlID.
- If the field or property is single valued, then the type of
the property or field must contain a property or field
annotated with @XmlID.
Note: If the collection item type or the type of the property (for non collection type) is java.lang.Object, then the instance must contain a property/field annotated with @XmlID attribute.
- This annotation can be used with the following annotations:
XmlElement
,XmlAttribute
,XmlList
, andXmlElements
.
Example: Map a JavaBean property to xs:IDREF (i.e. by reference rather than by containment)
//EXAMPLE: Code fragment public class Shipping { @XmlIDREF public Customer getCustomer(); public void setCustomer(Customer customer); .... } <!-- Example: XML Schema fragment --> <xs:complexType name="Shipping"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:IDREF"/> .... </xs:sequence> </xs:complexContent> </xs:complexType>
Example 2: The following is a complete example of containment versus reference.
// By default, Customer maps to complex type xs:Customer public class Customer { // map JavaBean property type to xs:ID @XmlID public String getCustomerID(); public void setCustomerID(String id); // .... other properties not shown } // By default, Invoice maps to a complex type xs:Invoice public class Invoice { // map by reference @XmlIDREF public Customer getCustomer(); public void setCustomer(Customer customer); // .... other properties not shown here } // By default, Shipping maps to complex type xs:Shipping public class Shipping { // map by reference @XmlIDREF public Customer getCustomer(); public void setCustomer(Customer customer); } // at least one class must reference Customer by containment; // Customer instances won't be marshalled. @XmlElement(name="CustomerData") public class CustomerData { // map reference to Customer by containment by default. public Customer getCustomer(); // maps reference to Shipping by containment by default. public Shipping getShipping(); // maps reference to Invoice by containment by default. public Invoice getInvoice(); } <!-- XML Schema mapping for above code frament --> <xs:complexType name="Invoice"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:IDREF"/> .... </xs:sequence> </xs:complexContent> </xs:complexType> <xs:complexType name="Shipping"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:IDREF"/> .... </xs:sequence> </xs:complexContent> </xs:complexType> <xs:complexType name="Customer"> <xs:complexContent> <xs:sequence> .... </xs:sequence> <xs:attribute name="CustomerID" type="xs:ID"/> </xs:complexContent> </xs:complexType> <xs:complexType name="CustomerData"> <xs:complexContent> <xs:sequence> <xs:element name="customer" type="xs:Customer"/> <xs:element name="shipping" type="xs:Shipping"/> <xs:element name="invoice" type="xs:Invoice"/> </xs:sequence> </xs:complexContent> </xs:complexType> <xs:element name"customerData" type="xs:CustomerData"/> <!-- Instance document conforming to the above XML Schema --> <customerData> <customer customerID="Alice"> .... </customer> <shipping customer="Alice"> .... </shipping> <invoice customer="Alice"> .... </invoice> </customerData>
Example 3: Mapping List to repeating element of type IDREF
// Code fragment public class Shipping { @XmlIDREF @XmlElement(name="Alice") public List customers; } <!-- XML schema fragment --> <xs:complexType name="Shipping"> <xs:sequence> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element name="Alice" type="xs:IDREF"/> </xs:choice> </xs:sequence> </xs:complexType>
Example 4: Mapping a List to a list of elements of type IDREF.
//Code fragment public class Shipping { @XmlIDREF @XmlElements( @XmlElement(name="Alice", type="Customer.class") @XmlElement(name="John", type="InternationalCustomer.class") public List customers; } <!-- XML Schema fragment --> <xs:complexType name="Shipping"> <xs:sequence> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element name="Alice" type="xs:IDREF"/> <xs:element name="John" type="xs:IDREF"/> </xs:choice> </xs:sequence> </xs:complexType>
- Since:
- JAXB2.0
- Version:
- $Revision: 1.12 $
- Author:
- Sekhar Vajjhala, Sun Microsystems, Inc.
- See Also:
XmlID
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