Java 更改 JAXB 编组器生成的 XML 标头

Altering the XML header produced by the JAXB marshaller

提问by JME

I am currently using the following code to marshal an object into an xml string

我目前正在使用以下代码将对象编组为 xml 字符串

    JAXBContext context;

    try {
        context = JAXBContext.newInstance(heartbeat.getClass());
        StringWriter writer = new StringWriter();
        Marshaller marshaller = context.createMarshaller();

        heartbeat.setHeader(header);
        heartbeat.setHeartbeatEvent(event);

        marshaller.marshal(heartbeat, writer);
        String stringXML = writer.toString();
        return stringXML;

    } catch (JAXBException e) {
        throw new RuntimeException("Problems generating XML in specified "
                + "encoding, underlying problem is " + e.getMessage(),
                e);
    }

Which produces the following header

产生以下标题

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

My desired output is the following

我想要的输出如下

<?xml version=\"1.0\"?>

By adding this to the marshaller

通过将其添加到编组器

marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.FALSE);
marshaller.setProperty("com.sun.xml.bind.xmlHeaders", "<?xml version=\"1.0\"?>");

I receive

我收到

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><?xml version="1.0"?>

and changing the JAXB_FRAGMENT property to TRUE removes the header entirely. I have been following the JAXB - Remove 'standalone="yes"' from generated XMLthread attempting to solve the problem but I have had no luck so far. Can someone please give me some insight on how to get my desired header from the JAXB marshaller?

并将 JAXB_FRAGMENT 属性更改为 TRUE 会完全删除标头。我一直在关注JAXB - 从生成的 XML线程中删除 'standalone="yes"'试图解决这个问题，但到目前为止我没有运气。有人能给我一些关于如何从 JAXB 编组器获取我想要的标头的见解吗？

采纳答案by bdoughan

When marshalling to an OutputStreamusing a combination of the following produces the expected output.

当编组到OutputStream使用以下组合时会产生预期的输出。

    marshaller.setProperty("com.sun.xml.bind.xmlHeaders", "<?xml version=\"1.0\"?>");
    marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true);

The problem you are seeing occurs when you marshal to a Writer, which appears to be a bug in the JAXB reference implementation. You can raise an issue at the link below:

当您编组到 时会出现您所看到的问题Writer，这似乎是 JAXB 参考实现中的一个错误。您可以通过以下链接提出问题：

• https://java.net/jira/browse/JAXB/

• https://java.net/jira/browse/JAXB/

---

---

You could always do:

你总是可以这样做：

JAXBContext context;

try {
    context = JAXBContext.newInstance(heartbeat.getClass());
    StringWriter writer = new StringWriter();
    writer.append("<?xml version=\"1.0\"?>");
    Marshaller marshaller = context.createMarshaller();
    marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true);

    heartbeat.setHeader(header);
    heartbeat.setHeartbeatEvent(event);

    marshaller.marshal(heartbeat, writer);
    String stringXML = writer.toString();
    return stringXML;

} catch (JAXBException e) {
    throw new RuntimeException("Problems generating XML in specified "
            + "encoding, underlying problem is " + e.getMessage(),
            e);
}

---

---

EclipseLink JAXB (MOXy)also supports the com.sun.xml.bind.xmlHeadersand it works correctly when marshalling to a Writer(I'm the MOXy lead)

EclipseLink JAXB (MOXy)也支持com.sun.xml.bind.xmlHeaders并且在编组到 a 时它可以正常工作Writer（我是 MOXy 的负责人）

• http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html

• http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html

回答by Gopi Krishna

This worked for me

这对我有用

marshaller.setProperty("com.sun.xml.internal.bind.xmlHeaders", "<?xml version=\"1.0\" encoding=\"UTF-8\"?>");

marshaller.setProperty("com.sun.xml.internal.bind.xmlHeaders", "<?xml version=\"1.0\" encoding=\"UTF-8\"?>");