使用JAXB从两个XML文件交叉引用XmlID

Question

我正在尝试将两个不同的XML文件编组/解组到POJOS.第一个XML文件如下所示:

--Network.xml--
<Network>
  <Nodes>
    <Node id="ROD" />
    <Node id="KFI" />
    <Node id="JND" />
  </Nodes>
  <Arcs>
    <Arc fromNode="ROD" />
    <Arc fromNode="JND" />
  </Arcs>
</Network>
---------

使用@XmlID和@XmlIDREF注释,我可以成功填充Arc类以指向它引用的正确节点.

但是,我还必须解析这个XML:

--NetworkInputs.xml--
<NetworkInputs>
  <Flows>
    <Flow toNode="JND" />
    <Flow toNode="ROD" />
  </Flows>
</NetworkInputs>
------

目前,我的程序成功解组了Network对象,但是Network和NetworkInput之间没有连接,允许JAXB"看到"Network中存在的节点.我希望我的Flow对象指向Network类中的正确Node.

我基本上想要这样做:http: //old.nabble.com/JAXB-Unmarshalling-and-XmlIDREF-using-different-stores-td14035248.html

我尝试实现这个:http: //weblogs.java.net/blog/kohsuke/archive/2005/08/pluggable_ididr.html 它只是不起作用,因为我无法获取我填充的网络的节点数据静态上下文.

甚至可以做这样的事情吗？

Answer 1

这可以使用XmlAdapter完成.诀窍是需要使用Network.xml中的所有节点初始化XmlAdapter并将其传递给与NetworkInputs.xml一起使用的Unmarshaller:

import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Network.class, NetworkInputs.class);

        File networkXML = new File("Network.xml");
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        Network network = (Network) unmarshaller.unmarshal(networkXML);

        File networkInputsXML = new File("NetworkInputs.xml");
        Unmarshaller unmarshaller2 = jc.createUnmarshaller();
        NodeAdapter nodeAdapter = new NodeAdapter();
        for(Node node : network.getNodes()) {
            nodeAdapter.getNodes().put(node.getId(), node);
        }
        unmarshaller2.setAdapter(nodeAdapter);
        NetworkInputs networkInputs = (NetworkInputs) unmarshaller2.unmarshal(networkInputsXML);

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

诀窍是使用XmlAdapter映射Flow上的toNode属性:

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

public class Flow {

    private Node toNode;

    @XmlAttribute
    @XmlJavaTypeAdapter(NodeAdapter.class)
    public Node getToNode() {
        return toNode;
    }

    public void setToNode(Node toNode) {
        this.toNode = toNode;
    }

}

适配器将如下所示.诀窍是我们将一个知道所有节点的已配置XmlAdapter传递给unmarshaller:

import java.util.HashMap;
import java.util.Map;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class NodeAdapter extends XmlAdapter<String, Node>{

    private Map<String, Node> nodes = new HashMap<String, Node>();

    public Map<String, Node> getNodes() {
        return nodes;
    }

    @Override
    public Node unmarshal(String v) throws Exception {
        return nodes.get(v);
    }

    @Override
    public String marshal(Node v) throws Exception {
        return v.getId();
    }

}