jaxb unmarshal to object by type
Question
I want to parse out different types based on xml, when header=1 then User, header=2 then Order etc. for example:
<entity>
<header>1</header>
<body>
<userId>1</userId>
<userName>jonh</userName>
...
<body>
</entity>
<entity>
<header>2</header>
<body>
<orderId>1</orderId>
<orderNo>20200101</orderNo>
...
<body>
</entity>
How to implement this function?
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
Object object = unmarshaller.unmarshal(xml);
2 answers
solution1
0 2020-09-17 11:46:41
I would try this: provide the type when unmarshalling. So maybe do something like this: create a transient facade object:
public class XmlEntityFacade {
private int header;
private Object body;
//getters and setters...
}
And then cast this type while unmarshalling:
...
XmlEntityFacade facade = (XmlEntityFacade) unmarshaller.unmarshal(xml);
Then you can access the value of the by calling .getHeader() and body with .getBody() (getters that you have provided XmlEntityFacade class). And then depending on the value cast the required type to the Object.
solution2
0 2020-09-18 14:06:03
public class TwiceUnmarshalTest {
@Data
@ToString
public static abstract class HeaderResponse {
private String header;
}
@XmlRootElement(name = "entity")
@XmlAccessorType(XmlAccessType.FIELD)
public static class XmlHeaderResponse extends HeaderResponse {
}
private final String xml = "<entity>" +
" <header>2</header>" +
" <body>" +
" <orderId>1</orderId>" +
" <orderNo>2020</orderNo>" +
" </body>" +
"</entity>";
@SuppressWarnings("unchecked")
public static <T> T unmarshal(Reader reader, Class<T> typeClass) throws Exception {
JAXBContext jaxbContext = JAXBContext.newInstance(typeClass);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
return (T) unmarshaller.unmarshal(reader);
}
@Test
public void headerResponse() throws Exception {
HeaderResponse response = unmarshal(new StringReader(xml), XmlHeaderResponse.class);
System.out.println(response);
}
@ToString(callSuper = true)
public static abstract class Response<T> extends HeaderResponse {
@XmlAnyElement(lax = true)
public T body;
}
@Data
@XmlRootElement(name = "body")
public static class Order {
private String orderId;
private String orderNo;
}
@XmlRootElement(name = "entity")
@XmlSeeAlso({Order.class})
public static class OrderResponse extends Response<Order> {
}
@Test
public void response() throws Exception {
XmlHeaderResponse response = unmarshal(new StringReader(xml), XmlHeaderResponse.class);
System.out.println(response);
//TwiceUnmarshalTest.HeaderResponse(header=2)
if (response.getHeader().equals("2")) {
OrderResponse orderResponse = unmarshal(new StringReader(xml), OrderResponse.class);
System.out.println(orderResponse);
//TwiceUnmarshalTest.Response(super=TwiceUnmarshalTest.HeaderResponse(header=2), body=TwiceUnmarshalTest.Order(orderId=1, orderNo=2020))
}
}
}
unmarshal twice, just get the header first, then get the entity. Not very good but can be used.
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