JAXB/MOXy适应XMLElementWrapper

Question

我试图使用JAXB/MOXy映射由一组接口表示的域，这些接口具有一个独特的特性:所有多值元素都封装在Iterables中，而不是数组或Collection。下面是一个演示我的情况的玩具示例。

Iterable<Movie>**)** Actor.java (注意Actor.java的使用)

package test.moxy;

public interface Actor {

    public String getName();
    public void setName(String name);

    public Iterable<Movie> getMovies();
    public void setMovies(Iterable<Movie> movies);

}

Movie.java

package test.moxy;

public interface Movie {

    public String getTitle();
    public void setTitle(String title);

}

主类

package test.moxy;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

import org.eclipse.persistence.jaxb.JAXBContextProperties;
import org.xml.sax.InputSource;

public class TestBinding {

    public static void main(String[] args) throws FileNotFoundException, JAXBException {

        Class<?>[] types = new Class<?>[] { Actor.class, Movie.class };

        List<String> mappings = new ArrayList<String>();
        mappings.add("test/moxy/oxm.xml");

        Map<String, Object> properties = new HashMap<String, Object>();
        properties.put(JAXBContextProperties.OXM_METADATA_SOURCE, mappings);

        JAXBContext jc = JAXBContext.newInstance(types, properties);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        InputSource is = new InputSource(new FileInputStream("src/main/java/test/moxy/input.xml"));
        Actor actor = (Actor) unmarshaller.unmarshal(is);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(actor, System.out);

    }

}

input.xml

<?xml version="1.0" encoding="UTF-8"?>
<actor>
    <name>John Smith</name>
    <movies>
        <movie>
            <title>Smith's Trilogy - Part I</title>
        </movie>
        <movie>
            <title>Smith's Trilogy - Part II</title>
        </movie>
        <movie>
            <title>Smith's Trilogy - Part III</title>
        </movie>
    </movies>
</actor>

oxm.xml

<?xml version="1.0" encoding="UTF-8"?>
<xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="test.moxy" xml-mapping-metadata-complete="true">
    <java-types>
        <java-type name="Actor">
        <xml-root-element name="actor" />
            <xml-type prop-order="name movies" factory-class="test.moxy.ProxyFactory"
                factory-method="initActor" />
            <java-attributes>
                <xml-element java-attribute="name" />
                <xml-element java-attribute="movies" name="movie" >
                    <xml-element-wrapper name="movies" />
                </xml-element>
            </java-attributes>
        </java-type>
        <java-type name="Movie">
            <xml-root-element name="movie" />
            <xml-type factory-class="test.moxy.ProxyFactory"
                factory-method="initMovie" />
            <java-attributes>
                <xml-element java-attribute="title" />
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

ProxyFactory是一个标准工厂，如http://blog.bdoughan.com/2010/07/moxy-jaxb-map-interfaces-to-xml.html中的例子。

目前，我得到了以下JAXBException：异常描述:只允许在集合或数组属性上使用XmlElementWrapper，但电影不是集合或数组属性。

我尝试使用电影上的XMLAdapter在Iterable<T>和List<T>之间进行转换，但它似乎适用于每个movie元素，而不是movies包装器。我想知道我是否以及如何为包装指定某种类型的XMLAdapter？

Answer 1

正如异常声明的那样，您将无法用Iterable类型的属性映射@XmlElementWrapper。

Exception in thread "main" javax.xml.bind.JAXBException: 
Exception Description: XmlElementWrapper is only allowed on a collection or array property but [movies] is not a collection or array property.
 - with linked exception:
[Exception [EclipseLink-50015] (Eclipse Persistence Services - @VERSION@.@QUALIFIER@): org.eclipse.persistence.exceptions.JAXBException
Exception Description: XmlElementWrapper is only allowed on a collection or array property but [movies] is not a collection or array property.]
    at org.eclipse.persistence.jaxb.JAXBContext$TypeMappingInfoInput.createContextState(JAXBContext.java:1068)
    at org.eclipse.persistence.jaxb.JAXBContext.<init>(JAXBContext.java:182)

XmlAdapter (MoviesAdapter)

相反，我们将使用XmlAdapter将Iterable转换为我们可以映射的东西。在本例中，我们将组成一个名为Movies的类的实例，它具有List of Movie实例。

package test.moxy;

import java.util.*;
import javax.xml.bind.annotation.adapters.XmlAdapter;

public class MoviesAdapter extends XmlAdapter<MoviesAdapter.Movies, Iterable<Movie>> {

    public static class Movies {
        public List<Movie> movie = new ArrayList<Movie>();
    }

    @Override
    public Iterable<Movie> unmarshal(Movies v) throws Exception {
        return v.movie;
    }

    @Override
    public Movies marshal(Iterable<Movie> v) throws Exception {
        Movies movies = new Movies();
        for(Movie movie : v) {
            movies.movie.add(movie);
        }
        return movies;
    }

}

外部元数据(oxm.xml)

下面是引用oxm.xml的修改后的XmlAdapter。使用新的映射，Movies对象将导致movies元素的存在，因此我们不再需要@XmlElementWrapper元数据。

<?xml version="1.0" encoding="UTF-8"?>
<xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="test.moxy" xml-mapping-metadata-complete="true">
    <java-types>
        <java-type name="Actor">
        <xml-root-element name="actor" />
            <xml-type prop-order="name movies" factory-class="test.moxy.ProxyFactory"
                factory-method="initActor" />
            <java-attributes>
                <xml-element java-attribute="name" />
                <xml-element java-attribute="movies">
                    <xml-java-type-adapter value="test.moxy.MoviesAdapter"/>
                </xml-element>
            </java-attributes>
        </java-type>
        <java-type name="Movie">
            <xml-root-element name="movie" />
            <xml-type factory-class="test.moxy.ProxyFactory"
                factory-method="initMovie" />
            <java-attributes>
                <xml-element java-attribute="title" />
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>