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如何将JAXB对象编组到org.w3c.dom.Document？

问题内容：

这给了我一个Document对象，它的顶层节点没有子节点：

public static Document getDocument(Object jaxb)
{
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    //dbf.setNamespaceAware(true);
    Document doc = dbf.newDocumentBuilder().newDocument();

    JAXBContext context = JAXBContext.newInstance(jaxb.getClass());
    context.createMarshaller().marshal(jaxb, doc);

    return doc;
}

这是变通方法，似乎效率更高，因为它先转换为String，然后转换为Document。

public static Document getDocument(Object jaxb)
{                           
    StringWriter writer = new StringWriter();       
    JAXBContext context = JAXBContext.newInstance(jaxb.getClass());
    context.createMarshaller().marshal(jaxb, writer);

    return DocumentBuilderFactory.newInstance().newDocumentBuilder().
parse(new InputSource(new StringReader(writer.toString()));
}

是否有可能完成我要完成的工作？


问题答案：

你在做什么应该工作。这是一个例子：

领域模型（Foo）

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Foo {

    private String bar;

    public String getBar() {
        return bar;
    }

    public void setBar(String bar) {
        this.bar = bar;
    }

}

演示版

import javax.xml.bind.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;

public class Demo {

    public static void main(String[] args) throws Exception {
        // Create the JAXBContext
        JAXBContext jc = JAXBContext.newInstance(Foo.class);

        // Create the Object
        Foo foo = new Foo();
        foo.setBar("Hello World");

        // Create the Document
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document document = db.newDocument();

        // Marshal the Object to a Document
        Marshaller marshaller = jc.createMarshaller();
        marshaller.marshal(foo, document);

        // Output the Document
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer t = tf.newTransformer();
        DOMSource source = new DOMSource(document);
        StreamResult result = new StreamResult(System.out);
        t.transform(source, result);
    }

}

输出量

<?xml version="1.0" encoding="UTF-8" standalone="no"?><foo><bar>Hello World</bar></foo>