-
@Retention(RUNTIME) @Target({字段,METHOD}) public @interface XmlIDREF
将JavaBean属性映射到XML IDREF。
为了保持XML序列化和XML反序列化之间的对象图的引用完整性,需要通过引用或遏制来适当地封送对象引用。 注释
@XmlID
和@XmlIDREF
一起允许通过遏制或引用定制映射JavaBean属性的类型。用法
@XmlIDREF
注释可以与以下程序元素一起使用:- 一个JavaBean属性
- 非静态,非瞬态场
有关其他常见信息,请参阅javax.xml.bind.package javadoc中的“Package Specification”。
用法受以下限制:
- 如果字段或属性的类型是集合类型,则集合项目类型必须包含用
@XmlID
注释的属性或字段。 - 如果字段或属性是单值,则属性或字段的类型必须包含一个注释为
@XmlID
的属性或字段。注意:如果集合项目类型或属性类型(对于非集合类型)为java.lang.Object,则该实例必须包含带有
@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
,并XmlElements
。
示例:将JavaBean属性映射到
xs:IDREF
(即通过引用而不是通过遏制)//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:以下是遏制与参考的完整示例。
// By default, Customer maps to complex type
xs:Customer
public class Customer { // map JavaBean property type toxs:ID
@XmlID public String getCustomerID(); public void setCustomerID(String id); // .... other properties not shown } // By default, Invoice maps to a complex typexs: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 typexs: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>
- 从以下版本开始:
- 1.6,JAXB 2.0
- 另请参见:
-
XmlID