是否可以使用JAXB（或JAXB + StAX）编组XML的一部分？ [英] Can a part of XML be marshalled using JAXB (or JAXB + StAX)?

问题描述

我有一个非常庞大的XML结构。
我想通过解组一个元素然后应用业务逻辑来更新这个XML的部分。

I have an XML structure which is very huge. I want to update the parts of this XML, by unmarshalling one element and then applying business logic.

我能够将子元素解组成POJO 。我想在Java中对这个POJO进行更改，然后在同一位置将其更新回XML。

I am able to unmarshal a child element into a POJO. I want to make changes to this POJO in Java and then update it back to the XML at the same location.

这在JAXB中是否可行？或者使用JAXB + StAX的组合。

Is this possible in JAXB? Or by using the combination of JAXB + StAX.

示例结构：

 <folder id="c5718b36-bab1-4c08-8f75-8e2f9aee42c5" name="Folder-1">
        <description> folder Desc</description>
        <createdBy>User2</createdBy>
        <hidden>false</hidden>

        <file id="4f2efb42-0604-4878-9e1e-ae90d66fb836" name="File-1">
            <description>file desc</description>
            <createdBy>User1</createdBy>
            <hidden>false</hidden>
        </file>
 </folder>

在上面的例子中，我能够将'file'元素解组为POJO。我想对此POJO进行更改，然后在XML文件中的正确位置更新它。

In the above example, I am able to unmarshal a 'file' element into a POJO. I want to make changes to this POJO and then update the same in the XML file at its correct location.

如何完成此操作？

请帮帮我。
谢谢。

Please help me. Thanks.

推荐答案

您可以使用JAXB和StAX执行以下操作：

You could do the following with JAXB and StAX:

import javax.xml.bind.*;
import javax.xml.stream.*;
import javax.xml.stream.events.XMLEvent;
import java.io.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        XMLInputFactory xif = XMLInputFactory.newFactory();
        XMLOutputFactory xof = XMLOutputFactory.newFactory();

        try(
           FileInputStream in = new FileInputStream("in.xml");
           FileOutputStream out = new FileOutputStream("out.xml");
        ) {
            XMLEventReader xer = xif.createXMLEventReader(in);
            XMLEventWriter xew = xof.createXMLEventWriter(out);

            JAXBContext jc = JAXBContext.newInstance(File.class);
            Unmarshaller unmarshaller = jc.createUnmarshaller();
            Marshaller marshaller = jc.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true);

            while(xer.hasNext()) {
                if(xer.peek().isStartElement() && xer.peek().asStartElement().getName().getLocalPart().equals("file")) {
                    // Unmarshal the File object from the XMLEventReader
                    File file = (File) unmarshaller.unmarshal(xer);

                    // Modify the File object
                    file.description = "NEW DESCRIPTION";

                    // Marshal the File object to the XMLEventWriter
                    marshaller.marshal(file, xew);
                } else {
                    // Copy node from reader to writer
                    xew.add(xer.nextEvent());
                }
            }
        }
    }

}

这篇关于是否可以使用JAXB（或JAXB + StAX）编组XML的一部分？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！