在不进行包装类的情况下，如何封送Jaxb元素列表? [英] How would I marshal a List of Jaxb Elements without making a wrapper class?

问题描述

实际组成编写器并将每个元素附加到字符串上的简短操作.有没有一种方法可以让JAXB编组器编组对象列表，而我可以在其中列出顶层元素的名称?

Short of actually making up a writer and appending each element onto the string. Is there a way to get the JAXB marshaller to marshall a list of objects where I can just give it the name of the top element?

我觉得我对此很了解

//http://blog.bdoughan.com/2012/07/jaxb-no-annotations-required.html
public <T> String jaxb(Collection<T> o, Class<T> clazz, String plural){
    try {
        ArrayList<T> al = new ArrayList<T>(o.size());
        al.addAll(o);
        JAXBContext jc = JAXBContext.newInstance(ArrayList.class);
        JAXBElement<ArrayList> amenity = new JAXBElement(new QName(plural), ArrayList.class, al);
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        StringWriter writer = new StringWriter();
        marshaller.marshal(amenity, writer);
        return writer.toString();
    } catch (JAXBException e) {
        throw new RuntimeException(e);
    }
}

但是结果仍然是一个空列表

but the result is still coming back as an empty list

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

有没有一种方法，而不仅仅是将xml字符串手动粘贴到一起?

Is there a way to do this without just manually pasting strings of xml together?

在Michael Glavassevich的帮助下，我已经做了一个警告，单个元素是< Item> s

With some help from Michael Glavassevich I've been able to do this with one caveat, the individual elements are <Item>s

//http://blog.bdoughan.com/2012/07/jaxb-no-annotations-required.html
@SuppressWarnings({ "unchecked", "rawtypes" })
public <T> String jaxb(Collection<T> elements, Class<T> elementClass, String plural){
    try {
        T[] array = (T[]) Array.newInstance(elementClass, elements.size());
        elements.toArray(array);
        JAXBContext jc = JAXBContext.newInstance(array.getClass());
        JAXBElement<T[]> topElement = new JAXBElement(new QName(plural), array.getClass(), array);
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        StringWriter writer = new StringWriter();
        marshaller.marshal(topElement, writer);
        return writer.toString();
    } catch (JAXBException e) {
        throw new RuntimeException(e);
    }
}

结果变为

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Basketballs>
    <item>basketball one</item>
    <item>basketball two</item>
</Basketballs>

推荐答案

如果不想创建包装类，可以将集合转换为数组，然后将该数组放入 JAXBElement 然后将其封送.

If you don't want to create a wrapper class you could convert the collection into an array, place that array in a JAXBElement and then marshal it.

例如:

public class JAXBArrayWriter {

    public static class Item {
        @XmlValue
        protected String value;

        public Item() {}

        public Item(String value) {
            this.value = value;
        }
    }

    public static void main (String [] args) throws Exception {
        List<Item> items = new ArrayList<Item>();
        items.add(new Item("one"));
        items.add(new Item("two"));
        JAXBContext jc = JAXBContext.newInstance(Item[].class);
        JAXBElement<Item[]> root = new JAXBElement<Item[]>(new QName("items"), 
                Item[].class, items.toArray(new Item[items.size()]));
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        StringWriter writer = new StringWriter();
        marshaller.marshal(root, writer);
        System.out.println(writer.toString());
    }
}

它将产生以下文档:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<items>
    <item>one</item>
    <item>two</item>
</items>

这篇关于在不进行包装类的情况下，如何封送Jaxb元素列表?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！