使用 JAXB 处理设计不佳的 XML

2022-01-19 00:00:00 java jaxb

我目前正在使用 JAXB 替换旧系统，但在解析 XML 时遇到了问题.系统的第一个要求是它必须是插入式替换，因此我无法修改 XML 的格式.下面是给我带来麻烦的 XML 部分.

I'm currently working on replacing a legacy system with JAXB and I'm running into problem with parsing the XML. The number one requirement of the system is that it must be a drop-in replacement so I cannot modify the format of the XML. Below is the XML section that is giving me trouble.

<xx>
    <s1>
        <X>-9999</X>
        <Y>-9999</Y>
    </s1>
    <s2>
        <X>-9999</X>
        <Y>-9999</Y>
   </s2>
</xx>

XML 的问题是所有 s# 对象都完全相同，最多可以有 256 个.JAXB 中有没有办法注释这样的标签，还是我必须创建 256 个单独的注释?任何帮助将不胜感激.

The issue with the XML is that all of the s# objects are the exact same and there can be up to 256 of them. Is there a way in JAXB to annotate such a tag or do I have to create 256 separate annotations? Any help would be most appreciated.

这里是 xx 对象的 java 代码.注意:该对象最初是在理解只有 2 个 s# 对象的情况下进行编程的，但此后发生了变化.

Here is the java code for the xx object. Note: the object was originally programmed with the understanding that there would only be 2 s# objects, but that since has changed.

@XmlRootElement(name="xx")

public class XMLXx implements Serializable {

    private static final long serialVersionUID = 4064597372833234503L;

    private XMLSite siteOne;
    private XMLSite siteTwo;

    @XmlElement(name="s1")
    public XMLSite getSiteOne() {
        return siteOne;
    }

    public void setSiteOne(XMLSite s1) {
        this.siteOne = s1;
    }

    @XmlElement(name="s2")
    public XMLSite getSiteTwo() {
        return siteTwo;
    }

    public void setSiteTwo(XMLSite s2) {
        this.siteTwo = s2;
    }
}

这里是 XMLSite 对象:

And here is the XMLSite object:

public class XMLSite implements Serializable {

    private static final long serialVersionUID = -4374405403222014476L;

    private Integer x;
    private Integer y;

    @XmlElement(name="X")
    public Integer getX() {
        return x;
    }

    public void setX(Integer x) {
        this.x = x;
    }

    @XmlElement(name="Y")
    public Integer getY() {
        return y;
    }

    public void setY(Integer y) {
        this.y = y;
    }
}

推荐答案

如果你想把 s# 处的项作为一个集合来处理:

If you want to handle at the s# items as a collection:

import java.io.Serializable;
import java.util.List;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="xx")
public class XMLXx implements Serializable {

    private static final long serialVersionUID = 4064597372833234503L;

    private List<XMLSite> sites;

    @XmlElement(name="s")
    public List<XMLSite> getSites() {
        return sites;
    }

    public void setSites(List<XMLSite> sites) {
        this.sites = sites;
    }

}

然后你可以做一些事情，比如欺骗 JAXB，让他们认为所有元素(s1、s2 等)实际上都称为 s:

Then you could do something like to fool JAXB into thinking all the elements (s1, s2, etc) are actually called s:

import java.io.FileInputStream;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;

public class Demo {

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

        XMLInputFactory xif = XMLInputFactory.newInstance();
        XMLStreamReader xsr = xif.createXMLStreamReader(new FileInputStream("input.xml"));
        xsr = new SiteStreamReaderDelegate(xsr);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        XMLXx object = (XMLXx) unmarshaller.unmarshal(xsr);
        System.out.println(object.getSites().size());

    }

    private static class SiteStreamReaderDelegate extends StreamReaderDelegate {

        public SiteStreamReaderDelegate(XMLStreamReader xsr) {
            super(xsr);
        }

        @Override
        public String getLocalName() {
            String localName = super.getLocalName();
            if(localName.startsWith("s")) {
                return "s";
            }
            return localName;
        }

    }
}

类似的例子见:

  • http://bdoughan.blogspot.com/2010/12/case-insensitive-unmarshalling.html

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