java – JAXB XML适配器通过注释工作,但不通过setAdapter

我了解所有关于如何使用 XMLAdapters到 convert unmappable types,或者只是改变某些对象如何序列化/反序列化为XML.如果我使用注释(包级别或其他方式),一切都会很好.问题是我正在尝试更改第三方对象的表示,我不能将源代码更改为(即为了注入注释).

这不应该是一个问题,考虑到Marshaller对象有一个方法manually adding adapters.不幸的是,无论我做什么,我不能得到这样的方式设置为“踢”.例如,我有一个类代表XYZ空间中的一个点(地心坐标).在我生产的XML中,我希望将其转换为lat / long / altitude(大地坐标).这是我的课程：

地心

package testJaxb;

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

@XmlRootElement
public class GeocentricCoordinate {
    // Units are in meters; see http://en.wikipedia.org/wiki/Geocentric_coordinates
    private double x;
    private double y;
    private double z;

    @XmlAttribute
    public double getX() {
        return x;
    }
    public void setX(double x) {
        this.x = x;
    }
    @XmlAttribute
    public double getY() {
        return y;
    }
    public void setY(double y) {
        this.y = y;
    }
    @XmlAttribute
    public double getZ() {
        return z;
    }
    public void setZ(double z) {
        this.z = z;
    }
}

大地

package testJaxb;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlRootElement;
/**
 * @see http://en.wikipedia.org/wiki/Geodetic_system
 */
@XmlRootElement
public class GeodeticCoordinate {

    private double latitude;
    private double longitude;
    // Meters
    private double altitude;

    public GeodeticCoordinate() {
        this(0,0);
    }

    public GeodeticCoordinate(double latitude,double longitude,double altitude) {
        super();
        this.latitude = latitude;
        this.longitude = longitude;
        this.altitude = altitude;
    }

    @XmlAttribute
    public double getLatitude() {
        return latitude;
    }
    public void setLatitude(double latitude) {
        this.latitude = latitude;
    }

    @XmlAttribute
    public double getLongitude() {
        return longitude;
    }

    public void setLongitude(double longitude) {
        this.longitude = longitude;
    }

    @XmlAttribute
    public double getAltitude() {
        return altitude;
    }
    public void setAltitude(double altitude) {
        this.altitude = altitude;
    }



}

GeocentricToGeodeticLocationAdapter

package testJaxb;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.adapters.XmlAdapter;


/**
 * One of our systems uses xyz coordinates to represent locations. Consumers of our XML would much
 * prefer lat/lon/altitude.  This handles converting between xyz and lat lon alt.  
 * 
 * @author ndunn
 *
 */
public class GeocentricToGeodeticLocationAdapter extends XmlAdapter<GeodeticCoordinate,GeocentricCoordinate> {

    @Override
    public GeodeticCoordinate marshal(GeocentricCoordinate arg0) throws Exception {
        // Todo: do a real coordinate transformation
        GeodeticCoordinate coordinate = new GeodeticCoordinate();
        coordinate.setLatitude(45);
        coordinate.setLongitude(45);
        coordinate.setAltitude(1000);
        return coordinate;
    }

    @Override
    public GeocentricCoordinate unmarshal(GeodeticCoordinate arg0) throws Exception {
        // Todo do a real coordinate transformation
        GeocentricCoordinate gcc = new GeocentricCoordinate();
        gcc.setX(100);
        gcc.setY(200);
        gcc.setZ(300);
        return gcc;
    }
}

ObjectWithLocation字段

package testJaxb; 
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class ObjectWithLocation {

    private GeocentricCoordinate location = new GeocentricCoordinate();

    public GeocentricCoordinate getLocation() {
        return location;
    }

    public void setLocation(GeocentricCoordinate location) {
        this.location = location;
    }


    public static void main(String[] args) {

        ObjectWithLocation object = new ObjectWithLocation();

        try {
            JAXBContext context = JAXBContext.newInstance(ObjectWithLocation.class,GeodeticCoordinate.class,GeocentricCoordinate.class);
            Marshaller marshaller = context.createMarshaller();

            marshaller.setAdapter(new GeocentricToGeodeticLocationAdapter());
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,true);

            marshaller.marshal(object,System.out);

        }
        catch (JAXBException jaxb) {
            jaxb.printstacktrace();
        }
    }
}

输出：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<objectWithLocation>
    <location z="0.0" y="0.0" x="0.0"/>
</objectWithLocation>

通过使用注释(在我的package-info.java文件中)：

@javax.xml.bind.annotation.adapters.XmlJavaTypeAdapters
({
@javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter(value=GeocentricToGeodeticLocationAdapter.class,type=GeocentricCoordinate.class),})

package package testJaxb;

我得到以下(所需)xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<objectWithLocation>
    <location longitude="45.0" latitude="45.0" altitude="1000.0"/>
</objectWithLocation>

所以我的问题是双重的.

>为什么适配器在注释时工作,但是通过setAdapter方法显式设置时不适用？
>如果我有类不能注释的类,并且我的package-info.java我不能修改以添加注释,我该如何解决这个问题？

解决方法

Marshaller上的setAdapter(XmlAdapter)用于传递已经使用@XmlJavaTypeAdapter注释的属性的初始化XmlAdapter.下面的链接是一个我利用这个行为的答案：

> Using JAXB to cross reference XmlIDs from two XML files

如果你想映射第三方类,你可以使用EclipseLink JAXB (MOXy)的XML映射文件(我是MOXy的主管)：

> http://bdoughan.blogspot.com/2010/12/extending-jaxb-representing-annotations.html