@XmlElementWrapper生成NullPointerException

Question

大家好 我试图代表以下xml代码：

        <AggregationMeta>
            <AggregationLink>
                <LocalName>stuff</LocalName>
                <Value>stuff</Value>
                <Meta/>
            </AggregationLink>
            <AggregationLink>
                <LocalName>stuff</LocalName>
                <Value>stuff</Value>
                <Meta/>
            </AggregationLink>
        </AggregationMeta>

我希望使用@XmlElementWrapper注释执行此操作。

这是我使用它的类：

public class VrIdnMeta {

private String lri;
private String nodeLocalName;
private List<Link> referenceLink;
private List<Link> aggregationLink;
private List<SimpleLink> backLink;
private List<SimpleLink> incomingChangeLink;

...

@XmlElementWrapper(name = "ReferenceMeta")
@XmlElement(name = "ReferenceLink")
public List<Link> getReferenceLink() {
    return referenceLink;
}

public void setReferenceLink(List<Link> referenceLink) {
    this.referenceLink = referenceLink;
}

@XmlElementWrapper(name = "AggregationMeta")
@XmlElement(name = "AggregationLink")
public List<Link> getAggregationLink() {
    return aggregationLink;
}

public void setAggregatioinLink(List<Link> aggregationLink) {
    this.aggregationLink = aggregationLink;
}

@XmlElementWrapper(name = "BackLinkMeta")
@XmlElement(name = "BackLink")
public List<SimpleLink> getBackLink() {
    return backLink;
}

public void setBackLink(List<SimpleLink> backLink) {
    this.backLink = backLink;
}

@XmlElementWrapper(name = "IncomingChangeMeta")
@XmlElement(name = "IncomingChangeLink")
public List<SimpleLink> getIncomingChangeLink() {
    return incomingChangeLink;
}

public void setIncomingChangeLink(List<SimpleLink> incomingChangeLink) {
    this.incomingChangeLink = incomingChangeLink;
}

}

这里是SimpleLink类

public class SimpleLink {

private String localName;
private String value;

...

@XmlElement(name = "LocalName")
public String getLocalName() {
    return localName;
}

public void setLocalName(String localName) {
    this.localName = localName;
}

@XmlElement(name = "Value")
public String getValue() {
    return value;
}

public void setValue(String value) {
    this.value = value;
}
}

最后是Link类

public class Link extends SimpleLink{

private String meta;

public Link(String localName, String value, String meta) {
    super(localName, value);
    this.meta = meta;
}

public Link() {
    super();
}

public Link(String localName, String value) {
    super(localName, value);
}

@XmlElement(name = "Meta")
public String getMeta() {
    return meta;
}

public void setMeta(String meta) {
    this.meta = meta;
}

}

当我使用Jaxb2将xml解组为上面写的那个时，问题出现了：我得到一个NullPointerException :-(。 我读到jaxb中有一个关于这个事实的错误，但它在2006年解决了，我使用的是spring 3（使用他自己的jaxb2库）。

任何人都有线索？

Answer 1

NPE似乎源于你的get和set方法的名称不匹配（在VrIdnMeta中）：

@XmlElementWrapper(name = "AggregationMeta")
@XmlElement(name = "AggregationLink")
public List<Link> getAggregationLink() {
    return aggregationLink;
}

public void setAggregatioinLink(List<Link> aggregationLink) {
    this.aggregationLink = aggregationLink;
}

当我将setAggregatioinLink更改为setAggregationLink时，我让您的示例按预期运行。