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Usage:
* ** Some Java types do not map naturally to a XML representation, for * example HashMap or other non JavaBean classes. Conversely, * a XML repsentation may map to a Java type but an application may * choose to accesss the XML representation using another Java * type. For example, the schema to Java binding rules bind * xs:DateTime by default to XmlGregorianCalendar. But an application * may desire to bind xs:DateTime to a custom type, * MyXmlGregorianCalendar, for example. In both cases, there is a * mismatch between bound type , used by an application to * access XML content and the value type, that is mapped to an * XML representation. * *
* This abstract class defines methods for adapting a bound type to a value * type or vice versa. The methods are invoked by the JAXB binding * framework during marshaling and unmarshalling: * *
Example: Customized mapping of HashMap
*The following example illustrates the use of * @XmlAdapter and @XmlJavaTypeAdapter to * customize the mapping of a HashMap. * *
Step 1: Determine the desired XML representation for HashMap. * *
* <hashmap> * <entry key="id123">this is a value</entry> * <entry key="id312">this is another value</entry> * ... * </hashmap> ** *
Step 2: Determine the schema definition that the * desired XML representation shown above should follow. * *
* * <xs:complexType name="myHashMapType"> * <xs:sequence> * <xs:element name="entry" type="myHashMapEntryType" * minOccurs = "0" maxOccurs="unbounded"/> * </xs:sequence> * </xs:complexType> * * <xs:complexType name="myHashMapEntryType"> * <xs:simpleContent> * <xs:extension base="xs:string"> * <xs:attribute name="key" type="xs:int"/> * </xs:extension> * </xs:simpleContent> * </xs:complexType> * ** *
Step 3: Write value types that can generate the above * schema definition. * *
* public class MyHashMapType { * List<MyHashMapEntryType> entry; * } * * public class MyHashMapEntryType { * @XmlAttribute * public Integer key; * * @XmlValue * public String value; * } ** *
Step 4: Write the adapter that adapts the value type, * MyHashMapType to a bound type, HashMap, used by the application. * *
* public final class MyHashMapAdapter extends * XmlAdapter<MyHashMapType,HashMap> { ... } * ** *
Step 5: Use the adapter. * *
* public class Foo { * @XmlJavaTypeAdapter(MyHashMapAdapter.class) * HashMap hashmap; * ... * } ** * The above code fragment will map to the following schema: * *
* <xs:complexType name="Foo"> * <xs:sequence> * <xs:element name="hashmap" type="myHashMapType" * </xs:sequence> * </xs:complexType> ** * @param