xml解析JAXB：如何解组由多个标记或属性值组成的Java对象

Question

我正在从SAX解析器转换到JAXB，无法理解如何将多个标记/属性值解组为单个（可兼容）Java POJO

我有如下xml文件：

<item validFrom="1950" validUntil="1980">
    <description>some text</description>
</item>

“validFrom”和“validUntil”值应组成有效的“可变范围”POJO（见下面的定义）

我需要将其解组到的Java项定义是：

@XmlRootElement
@XmlAccessorType(XmlAcccessType.FIELD)
public class Item {
    // ??? need help mapping this to be composed from "validFrom", "validUntil" attributes
    private MutableRange validRange;

    @XmlElement
    private String description;
}

// assume all other boilerplate code exists
public class MutableRange {
    private int lowerBound;
    private int upperBound;
}

我曾尝试使用适配器，但它并没有同时捕获“from”和“until”两个值来创建可变范围实例。我尝试使用@XmlMixed但没有成功

JAXB规定的实现方法是什么

一旦解决了这个问题，我将用（XmlAdapter）扩展MutableRange，作为包装器来创建番石榴的不可变范围对象，用@XmlJavaTypeAdapter(MutableRange.class)将它映射到validRange

Answer 1

注意：我是EclipseLink JAXB (MOXy)领导和JAXB (JSR-222)专家组成员

您可以使用MOXy的@XmlPath扩展来映射此用例：

@XmlRootElement
@XmlAccessorType(XmlAcccessType.FIELD)
public class Item {
    @org.eclipse.persistence.oxm.annotations.XmlPath(".")
    private MutableRange validRange;

    @XmlElement
    private String description;
}

了解更多信息

• http://blog.bdoughan.com/2010/07/xpath-based-mapping.html
• http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html

Answer 2

我会使用以下简单的方法：

public interface MutableRange() {
    public int getLowerBound();
    public int getUpperBound();
    public void setLowerBound(int lowerBound);
    public void setUpperBound(int upperBound);
}

@XmlRootElement(name = "item")
@XmlAccessorType(XmlAccessType.NONE)
public class Item {
    @XmlAttribute(name = "validFrom")
    private int validFrom;
    @XmlAttribute(name = "validUntil")
    private int validUntil;
    @XmlElement(name = "description")
    private String description;

    public MutableRange getValidRange() {
        return new MutableRange() {
            public int getLowerBound() { return validFrom; }
            public int getUpperBound() { return validUntil; }
            public void setLowerBound(int lowerBound) { validFrom = lowerBound; }
            public void setUpperBound(int upperBound) { validUntil = upperBound; }
        }
    }

    public String getDescription() {
       return description;
    }
}