如何告诉JAXB忽略父类的属性

2019年8月3日 349次阅读

我面临着JAXB的以下问题：看起来JAXB正在分析从最深的子类到父类的属性,并且子属性具有优先级.我想以某种方式改变这种行为.特别是：

儿童班：

package test.sub;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlTransient;


@XmlAccessorType(XmlAccessType.NONE)
public class BasicDocument {

    private String comment;

    public String getComment() {
        return comment;
    }

    public void setComment(String cost) {
        this.comment = cost;
    }
}

父类：

package test;

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

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

import test.sub.BasicDocument;

@XmlRootElement(name="Description", namespace="http://www.w3.org/1999/02/22-rdf-syntax-ns#")
@XmlAccessorType(XmlAccessType.PROPERTY)
class Document extends BasicDocument {

    private String identifier;

    @XmlElement(name = "identifier", namespace = "http://purl.org/dc/terms/")
    public String getIdentifier() {
        return identifier;
    }

    public void setIdentifier(String identifier) {
        this.identifier = identifier;
    }

    @Override
    @XmlElement(name = "abstract", namespace = "http://purl.org/dc/terms/")
    public String getComment() {
        return super.getComment();
    }

    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
    }
}

编组工作正常：

Document document = new Document();

document.setIdentifier("12A");
document.setComment("special");

StringWriter w = new StringWriter();

jaxbContext.createMarshaller().marshal(document, new StreamResult(w));

System.out.println(w);

输出：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns2:Description xmlns:ns2="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns="http://purl.org/dc/terms/">
    <abstract>special</abstract>
    <identifier>12A</identifier>
</ns2:Description>

但是编组会忽略子BasicDocument类中的属性(t.xml正好是上面的XML)：

JAXBContext jaxbContext = JAXBContext.newInstance(Document.class);

Document document = (Document) jaxbContext.createUnmarshaller().unmarshal(Document.class.getResourceAsStream("t.xml"));

System.out.println("out: " + document);

输出：

out: Document[identifier=12A,comment=<null>]

预期：

out: Document[identifier=12A,comment=special]

基本上,BasicDocument上的@XmlAccessorType(XmlAccessType.NONE)(见Ignore a parent class when Serializing to XML)无效.还要在包test.sub中创建package-info.java(见@XmlTransient on third-party or external super class),如下所示：

@XmlAccessorType(XmlAccessType.NONE)
package test.sub;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;

没有效果.只有@XmlTransient公共类BasicDocument才有效.理想情况下,我不想在子上添加任何注释,只能通过package-info.java控制此行为.我怎样才能做到这一点？

在JDK 1.6.0_27上测试,另外在类路径中使用JAXB 2.2.4-1运行时.

是功能还是bug？

最佳答案 您只需要将setComment方法添加到Document类.没有它,即使该方法存在于父类中,它也被视为只写属性.

public void setComment(String comment) {
    super.setComment(comment);
}

完整的文档来源

package test;

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

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

import test.sub.BasicDocument;

@XmlRootElement(name="Description", namespace="http://www.w3.org/1999/02/22-rdf-syntax-ns#")
@XmlAccessorType(XmlAccessType.PROPERTY)
class Document extends BasicDocument {

    private String identifier;

    @XmlElement(name = "identifier", namespace = "http://purl.org/dc/terms/")
    public String getIdentifier() {
        return identifier;
    }

    public void setIdentifier(String identifier) {
        this.identifier = identifier;
    }

    @Override
    @XmlElement(name = "abstract", namespace = "http://purl.org/dc/terms/")
    public String getComment() {
        return super.getComment();
    }

    public void setComment(String comment) {
        super.setComment(comment);
    }

    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
    }

}
点赞