JAXB/XSD：数字而不是元素名称

Question

我必须从xml文件创建Java对象（转换前我无法编辑），所以我认为最好创建一个XSD，然后通过JAXB取消marshall文件。问题是，该 XML 中有一些元素的格式如下所示：

<parent-element>
    <id-00001>...</id-00001>
    <id-00002>...</id-00002>
    ...
</parent-element>

所以基本上我有一个xml元素列表，元素的“名称”是列表中的顺序。每个列表中的元素数量可能不受限制。是否可以使用 JAXB 对此进行解构，或者我是否必须使用 XML 读取器并循环访问这些元素？“id-XXXXX”元素在内部都以相同的方式格式化，因此，如果将其格式化为“”，则可以没有任何问题。

提前致谢！

Answer 1

我猜你的有效载荷如下所示：XML<root>&nbsp; &nbsp; <parent-element>&nbsp; &nbsp; &nbsp; &nbsp; <id-00001>value 1</id-00001>&nbsp; &nbsp; &nbsp; &nbsp; <id-00002>value 2</id-00002>&nbsp; &nbsp; </parent-element></root>要读取具有动态名称的节点，我们需要编写自定义适配器（）。假设该模型如下所示：javax.xml.bind.annotation.adapters.XmlAdapter@XmlRootElement(name = "root")@XmlAccessorType(XmlAccessType.FIELD)class Root {&nbsp; &nbsp; @XmlElement(name = "parent-element")&nbsp; &nbsp; @XmlJavaTypeAdapter(IdsXmlAdapter.class)&nbsp; &nbsp; private MultiItemList list;&nbsp; &nbsp; // getters, setters, toString}class MultiItemList {&nbsp; &nbsp; private List<String> ids;&nbsp; &nbsp; // getters, setters, toString}对于上述和型号，自定义适配器可能如下所示：XMLPOJOclass IdsXmlAdapter extends XmlAdapter<Object, MultiItemList> {&nbsp; &nbsp; @Override&nbsp; &nbsp; public MultiItemList unmarshal(Object v) {&nbsp; &nbsp; &nbsp; &nbsp; Element element = (Element) v;&nbsp; &nbsp; &nbsp; &nbsp; NodeList childNodes = element.getChildNodes();&nbsp; &nbsp; &nbsp; &nbsp; List<String> ids = new ArrayList<>(childNodes.getLength());&nbsp; &nbsp; &nbsp; &nbsp; for (int i = 0; i < childNodes.getLength(); i++) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Node item = childNodes.item(i);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (item.getNodeName().equals("#text")) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; continue;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ids.add(item.getTextContent());&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; MultiItemList multiItemList = new MultiItemList();&nbsp; &nbsp; &nbsp; &nbsp; multiItemList.setIds(ids);&nbsp; &nbsp; &nbsp; &nbsp; return multiItemList;&nbsp; &nbsp; }&nbsp; &nbsp; @Override&nbsp; &nbsp; public Object marshal(MultiItemList v) throws Exception {&nbsp; &nbsp; &nbsp; &nbsp; return null; // Implement if needed&nbsp; &nbsp; }}用法示例：import org.w3c.dom.Element;import org.w3c.dom.Node;import org.w3c.dom.NodeList;import javax.xml.bind.JAXBContext;import javax.xml.bind.annotation.XmlAccessType;import javax.xml.bind.annotation.XmlAccessorType;import javax.xml.bind.annotation.XmlElement;import javax.xml.bind.annotation.XmlRootElement;import javax.xml.bind.annotation.adapters.XmlAdapter;import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;import java.io.File;import java.io.FileReader;import java.util.ArrayList;import java.util.List;public class JaxbApp {&nbsp; &nbsp; public static void main(String[] args) throws Exception {&nbsp; &nbsp; &nbsp; &nbsp; File xmlFile = new File("./resource/test.xml").getAbsoluteFile();&nbsp; &nbsp; &nbsp; &nbsp; JAXBContext jaxbContext = JAXBContext.newInstance(Root.class);&nbsp; &nbsp; &nbsp; &nbsp; Object unmarshal = jaxbContext.createUnmarshaller().unmarshal(new FileReader(xmlFile));&nbsp; &nbsp; &nbsp; &nbsp; System.out.println(unmarshal);&nbsp; &nbsp; }}指纹：Root{list=Root{ids=[value 1, value 2]}}请注意，由于异常，您无法直接实现适配器：XmlAdapter<Element, MultiItemList>Exception in thread "main" com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException: 1 counts of IllegalAnnotationExceptionsorg.w3c.dom.Element is an interface, and JAXB can't handle interfaces.&nbsp; &nbsp; this problem is related to the following location:&nbsp; &nbsp; &nbsp; &nbsp; at org.w3c.dom.Element

Answer 2

由于您的xml可能具有无限数量的“id元素”，因此创建匹配的POJO结构是很棘手的。您可以使用和适配器。 将不同的元素作为 dom 节点读取，您可以在适配器中处理它们。@XmlAnyElement@XmlAnyElement例如，使用下面给出的 xml：<parent-element>&nbsp; &nbsp; <id-00001>value 1</id-00001>&nbsp; &nbsp; <id-00002>value 2</id-00002></parent-element>您的根可能如下所示：@XmlRootElement(name = "parent-element")@XmlAccessorType(XmlAccessType.FIELD)public class Root {&nbsp; &nbsp; @XmlAnyElement&nbsp; &nbsp; @XmlJavaTypeAdapter(MyAdapter.class)&nbsp; &nbsp; private List<String> varyingElements;}和您的适配器，如下所示：public class MyAdapter extends XmlAdapter<Element, String> {&nbsp; &nbsp; @Override&nbsp; &nbsp; public Element marshal(String arg0) throws Exception {&nbsp; &nbsp; &nbsp; &nbsp; // do what you must&nbsp; &nbsp; &nbsp; &nbsp; return null;&nbsp; &nbsp; }&nbsp; &nbsp; @Override&nbsp; &nbsp; public String unmarshal(Element element) throws Exception {&nbsp; &nbsp; &nbsp; &nbsp; return element.getChildNodes().item(0).getNodeValue();&nbsp; &nbsp; }}元素如org.w3c.dom.Element