Specifying root and child nodes with JAXB

问题

Staying within JAXB how would I refactor MyNote so that it conforms to:

<note>
    <to>Tove</to>
    <from>Jani</from>
    <heading>Reminder</heading>
    <body>Don't forget me this weekend!</body>
</note>

Which is well formed but not valid, to my understanding. Current output:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MyNotes>
    <Note>
        <note>XY3Z1RGEO9W79LALCS</note>
        <to>LJAY9RNMUGGENGNND9</to>
        <from>GOVSHVZ3GJWC864L7X</from>
        <heading>EX6LGVE5LGY4A6B9SK</heading>
        <body>L95WYQNMEU1MFDRBG4</body>
    </Note>
</MyNotes>

which is too flat, rather than nested as the example.

I believe this makes note the root element, with other elements being children nodes to note if I'm using correct terminology.

The MyNote class:

package net.bounceme.dur.jaxb.hello.world;

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

@XmlType(propOrder = {"note", "to", "from", "heading", "body"})
@XmlRootElement(name = "note")
public class MyNote {

    private String note;
    private String to;
    private String from;
    private String heading;
    private String body;

    public String getNote() {
        return note;
    }

    @XmlElement(name = "note")
    public void setNote(String note) {
        this.note = note;
    }

    public String getTo() {
        return to;
    }

    @XmlElement(name = "to")
    public void setTo(String to) {
        this.to = to;
    }

    public String getFrom() {
        return from;
    }

    @XmlElement(name = "from")
    public void setFrom(String from) {
        this.from = from;
    }

    public String getHeading() {
        return heading;
    }

    @XmlElement(name = "heading")
    public void setHeading(String heading) {
        this.heading = heading;
    }

    public String getBody() {
        return body;
    }

    @XmlElement(name = "body")
    public void setBody(String body) {
        this.body = body;
    }

    @Override
    public String toString() {
        return note + to + from + heading + body;
    }

}

The MyNotes class:

package net.bounceme.dur.jaxb.hello.world;

import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "MyNotes")
public class MyNotes {

    private static final Logger LOG = Logger.getLogger(MyNotes.class.getName());

    private List<MyNote> myNotes = new ArrayList<>();

    public MyNotes() {
    }

    public List<MyNote> getMyNotes() {
        LOG.info(myNotes.toString());
        return myNotes;
    }

    @XmlElement(name = "Note")
    public void setMyNotes(List<MyNote> myNotes) {
        LOG.info(myNotes.toString());
        this.myNotes = myNotes;
    }

    public void add(MyNote myNote) {
        LOG.info(myNote.toString());
        myNotes.add(myNote);
    }

    @Override
    public String toString() {
        StringBuffer str = new StringBuffer();
        for (MyNote note : this.myNotes) {
            str.append(note.toString());
        }
        return str.toString();
    }

}

exercising the MyNote and MyNotes classes:

    public MyNotes unmarshallMyNotesFromFile(URI uri) throws Exception {
        File file = new File(uri);
        JAXBContext jaxbContext = JAXBContext.newInstance(MyNotes.class);
        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
        MyNotes myNotes = (MyNotes) jaxbUnmarshaller.unmarshal(file);
        return myNotes;
    }

    public void marshallMyNotesAndWriteToFile(MyNotes notes, URI uri) throws Exception {
        JAXBContext jaxbContext = JAXBContext.newInstance(MyNotes.class);
        Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
        jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        jaxbMarshaller.marshal(notes, new File(uri));
        jaxbMarshaller.marshal(notes, System.out);
    }

I'm looking to grab this xml through the web; first need to match the structure to the example.

回答1:

You are very close. You need to change how you name your xmlElement for myNotes in MyNotes class. Also MyNote should not have a note field itself (according to your desired xml). Your edited classes would look like this (I also removed the logging statements for my convenience):

@XmlType(propOrder = { "to", "from", "heading", "body"})
@XmlRootElement(name = "note")
public class MyNote {

    private String to;
    private String from;
    private String heading;
    private String body;

    public String getTo() {
        return to;
    }

    @XmlElement(name = "to")
    public void setTo(String to) {
        this.to = to;
    }

    public String getFrom() {
        return from;
    }

    @XmlElement(name = "from")
    public void setFrom(String from) {
        this.from = from;
    }

    public String getHeading() {
        return heading;
    }

    @XmlElement(name = "heading")
    public void setHeading(String heading) {
        this.heading = heading;
    }

    public String getBody() {
        return body;
    }

    @XmlElement(name = "body")
    public void setBody(String body) {
        this.body = body;
    }

    @Override
    public String toString() {
        return  to + from + heading + body;
    }

}

and MyNotes:

@XmlRootElement(name = "MyNotes")
public class MyNotes {

    private List<MyNote> myNotes = new ArrayList<>();

    public MyNotes() {
    }

    public List<MyNote> getMyNotes() {
        return myNotes;
    }

    @XmlElement(name = "note")
    public void setMyNotes(List<MyNote> myNotes) {
        this.myNotes = myNotes;
    }

    public void add(MyNote myNote) {
        myNotes.add(myNote);
    }

    @Override
    public String toString() {
        StringBuffer str = new StringBuffer();
        for (MyNote note : this.myNotes) {
            str.append(note.toString());
        }
        return str.toString();
    }

}

来源：https://stackoverflow.com/questions/54084450/specifying-root-and-child-nodes-with-jaxb

标签

java

xml

jaxb

marshalling

well-formed