使用 JAXB 從 XML 字符串創建對象

Question

如何使用以下代碼解組 XML 字符串並將其映射到下面的 JAXB 對象？

JAXBContext jaxbContext = JAXBContext.newInstance(Person.class);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
Person person = (Person) unmarshaller.unmarshal("xml string here");

---

@XmlRootElement(name = "Person")
public class Person {
    @XmlElement(name = "First-Name")
    String firstName;
    @XmlElement(name = "Last-Name")
    String lastName;
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

Answer 1

要傳遞 XML 內容，您需要將內容包裝在Reader ，然后對其進行解組：

JAXBContext jaxbContext = JAXBContext.newInstance(Person.class);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();

StringReader reader = new StringReader("xml string here");
Person person = (Person) unmarshaller.unmarshal(reader);

Answer 2

或者如果你想要一個簡單的單線：

Person person = JAXB.unmarshal(new StringReader("<?xml ..."), Person.class);

Answer 3

沒有unmarshal(String)方法。 您應該使用Reader ：

Person person = (Person) unmarshaller.unmarshal(new StringReader("xml string"));

但通常您是從某個地方獲取該字符串，例如文件。 如果是這種情況，最好通過FileReader本身。

Answer 4

如果您已經有了 xml，並且有多個屬性，您可以按如下方式處理：

String output = "<ciudads><ciudad><idCiudad>1</idCiudad>
<nomCiudad>BOGOTA</nomCiudad></ciudad><ciudad><idCiudad>6</idCiudad>
<nomCiudad>Pereira</nomCiudad></ciudads>";
DocumentBuilder db = DocumentBuilderFactory.newInstance()
    .newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(output));

Document doc = db.parse(is);
NodeList nodes = ((org.w3c.dom.Document) doc)
    .getElementsByTagName("ciudad");

for (int i = 0; i < nodes.getLength(); i++) {           
    Ciudad ciudad = new Ciudad();
    Element element = (Element) nodes.item(i);

    NodeList name = element.getElementsByTagName("idCiudad");
    Element element2 = (Element) name.item(0);
    ciudad.setIdCiudad(Integer
        .valueOf(getCharacterDataFromElement(element2)));

    NodeList title = element.getElementsByTagName("nomCiudad");
    element2 = (Element) title.item(0);
    ciudad.setNombre(getCharacterDataFromElement(element2));

    ciudades.getPartnerAccount().add(ciudad);
}
}

for (Ciudad ciudad1 : ciudades.getPartnerAccount()) {
System.out.println(ciudad1.getIdCiudad());
System.out.println(ciudad1.getNombre());
}

方法 getCharacterDataFromElement 是

public static String getCharacterDataFromElement(Element e) {
Node child = e.getFirstChild();
if (child instanceof CharacterData) {
CharacterData cd = (CharacterData) child;

return cd.getData();
}
return "";
}

Answer 5

If you want to parse using InputStreams

public Object xmlToObject(String xmlDataString) {
        Object converted = null;
        try {
        
            JAXBContext jc = JAXBContext.newInstance(Response.class);
        
            Unmarshaller unmarshaller = jc.createUnmarshaller();
            InputStream stream = new ByteArrayInputStream(xmlDataString.getBytes(StandardCharsets.UTF_8));
            
            converted = unmarshaller.unmarshal(stream);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
        return converted;
    }