Question

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);
    }

产生以下标题

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

我想要的输出如下

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

将此添加到编组

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

我收到了

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

并将JAXB_FRAGMENT属性更改为TRUE会完全删除标头。我一直在关注尝试解决问题的JAXB - Remove 'standalone="yes"' from generated XML线程，但到目前为止我没有运气。有人可以给我一些关于如何从JAXB marshaller获取所需标题的见解吗？

Answer 1

使用以下组合编组到OutputStream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);

当您编组到Writer时，您看到的问题就出现了，这似乎是JAXB参考实现中的错误。您可以通过以下链接提出问题：

https://java.net/jira/browse/JAXB/

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)也支持com.sun.xml.bind.xmlHeaders，当它编组为Writer时，它可以正常工作（我是MOXy领导）

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

Answer 2

这对我有用

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

更改JAXB marshaller生成的XML标头

2 个答案: