Reading Element attribute value using XStream

问题

I am not able lookup attribute value of an element. My XML is

<Person>
          <BirthDate>2008-01-04</BirthDate>
          <FirstName>Affo</FirstName>
          <Gender tc="200">Male</Gender>
          <LastName></LastName>
          <Occupation>false</Occupation>
          <Age>4</Age>
</Person>

I am interested in <Gender tc="200">Male</Gender>. My POJO looks like this:

    private String FirstName;
    private String LastName;
    private String Occupation;
    @XStreamAsAttribute
    @XStreamAlias("tc")
    private String genderTC;
    private String Gender;
    private String birthDate;
    private int age;

From XML is

            XStream stream = new XStream(new DomDriver());
        stream.processAnnotations(PersonType.class);
        PersonType person = (PersonType) stream.fromXML(file);

        System.out.println(person.getFirstName());
        System.out.println(person.getGenderTC());
        System.out.println(person.getGender());

Here for person.getGenderTC() I am getting null. Interesting part is when I reversed the process and generated the xml using same PersonType pojo, I got following XML:

<Person tc="111">
  <FirstName>Himanshu</FirstName>
  <Gender>M</Gender>
  <Age>28</Age>
</Person>

回答1:

@BlaiseDoughan That's great and I appreciate your support. Can you please tell me how can I integrate EclipseLink MOXy with my project without using jaxb.properties? What are the libraries/JARs to include? In between I am aware of EclipseLink JAXB (MOXy) implementation to get attribute. My only hunch is jaxb.properties file.

Person

Below is how you could use MOXy's @XmlPath annotation to do the mapping you are looking for:

package forum11417620;

import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.XmlPath;

@XmlRootElement(name="Person")
@XmlAccessorType(XmlAccessType.FIELD)
public class Person {

    @XmlElement(name="FirstName")
    private String firstName;

    @XmlElement(name="LastName")
    private String lastName;

    @XmlElement(name="Occupation")
    private String occupation;

    @XmlPath("Gender/@tc")
    private String genderTC;

    @XmlPath("Gender/text()")
    private String gender;

    @XmlElement(name="BirthDate")
    private String birthDate;

    @XmlElement(name="Age")
    private int age;

}

Demo

Below is an example of how you can bootstrap a MOXy JAXBContext without a jaxb.properties file.

package forum11417620;

import java.io.File;
import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.JAXBContextFactory;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContextFactory.createContext(new Class[] {Person.class}, null);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum11417620/input.xml");
        Person person = (Person) unmarshaller.unmarshal(xml);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(person, System.out);
    }

}

input.xml/Output

<?xml version="1.0" encoding="UTF-8"?>
<Person>
   <FirstName>Affo</FirstName>
   <LastName></LastName>
   <Occupation>false</Occupation>
   <Gender tc="200">Male</Gender>
   <BirthDate>2008-01-04</BirthDate>
   <Age>4</Age>
</Person>

Required Binaries (from http://www.eclipse.org/eclipselink/downloads/)

Option #1 - EclipseLink JAR (from Installer Zip)

eclipselink.jar

Option #2 - MOXy bundles (from OSGi Bundles Zip)

org.eclipse.persistence.moxy.jar
org.eclipse.persistence.core.jar
org.eclipse.persistence.asm.jar

Maven

I have example pom.xml files on Git Hub as part of some examples from my blog:

https://github.com/bdoughan

回答2:

As you have it, this code:

@XStreamAsAttribute 
@XStreamAlias("tc") 
private String genderTC;

is expecting the attribute tc to be on the enclosing Person node of the XML.

I think you need to define a second pojo type to deserialize the Gender data, including the genderTC attribute as well as the Gender element.

来源：https://stackoverflow.com/questions/11417620/reading-element-attribute-value-using-xstream

标签

java

xml

xstream