java - JAXB 解码到列表

Question

我正在尝试将此 XML 解码为 Java 对象，即包含电子邮件地址列表的 Customer 对象。

<customer>
 <emailAddresses>janed@example.com</emailAddresses>
 <emailAddresses>jdoe@example.org</emailAddresses>
</customer>

列表出现问题，我得到了正确的列表项数 (2)，但 emailAddresses 标记的值为 null

Customer.java

@XmlRootElement( name = "customer" )
public class Customer
{
    private List<EmailAddress> emailAddresses;

    public Customer()
    {
        emailAddresses = new ArrayList<EmailAddress>();
    }

    public List<EmailAddress> getEmailAddresses()
    {
        return emailAddresses;
    }

    public void setEmailAddresses( List<EmailAddress> emailAddresses )
    {
        this.emailAddresses = emailAddresses;
    }
}

EmailAddress.java

public class EmailAddress
{
    private String emailAddresses;

    public String getEmailAddresses()
    {
        return emailAddresses;
    }

        public void setEmailAddresses( String emailAddresses )
    {
        this.emailAddresses = emailAddresses;
    }
}

单元测试失败

@Test
public void shouldDeserialiseCusomerXMLToObject() throws JAXBException
{
    String xml = "<customer>"
            + "    <emailAddresses>janed@example.com</emailAddresses>"
            + "    <emailAddresses>jdoe@example.org</emailAddresses>"
            + "</customer>";

    JAXBContext jaxbContext = JAXBContext.newInstance( Customer.class );
    Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();

    StringReader reader = new StringReader( xml );
    Customer msg = ( Customer ) jaxbUnmarshaller.unmarshal( reader );

    // This passes, I have 2 emailAddresses
    assertEquals( 2, msg.getEmailAddresses().size() );

    // This fails, I have a null pointer instead of the email address
    assertEquals( "janed@example.com", msg.getEmailAddresses().get( 0 ).getEmailAddresses() );
}

Answer 1

emailAddresses EmailAddress领域默认情况下被视为子元素，期望 XML 为:

<customer>
    <emailAddresses>
        <emailAddresses>janed@example.com</emailAddresses>
    </emailAddresses>
    <emailAddresses>
        <emailAddresses>jdoe@example.org</emailAddresses>
    </emailAddresses>
</customer>

自从你外<emailAddresses>元素不包含内部 <emailAddresses>元素，该字段从未被分配。

您想要emailAddresses EmailAddress领域是(外部)<emailAddresses>的值元素，所以你必须告诉 JAXB通过指定 @XmlValue 注释:

@XmlValue
public String getEmailAddresses()
{
    return emailAddresses;
}

<小时/>

@XmlValue与 @XmlAttribute 结合使用时，注释特别有用，支持这样的 XML:

<Person sex="male" age="25">John Doe</Person>

类将在哪里:

public class Person {
    public enum Sex {
        @XmlEnumValue("male")   MALE,
        @XmlEnumValue("female") FEMALE,
    }
    @XmlAttribute
    private Sex sex;
    @XmlAttribute
    private int age;
    @Value
    private String name;
}