Jaxbで乾燥したままです
-
28-10-2019 - |
質問
次の形式でXMLにシリアル化する必要があるJavaクラスをいくつか開発しています。
<foo value="123"/>
<!-- or this -->
<bar value="abc"/>
<!-- or this -->
<baz value="true"/>
最初は、 Foo.java
このように見えた:
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
class Foo {
@XmlAttribute
String value;
// snip constructors
// snip methods
// getValue
// equals, hashCode, toString
// static valueOf(String), static valueOf(int)
}
何を推測するのにそれほど想像力が必要ではありません Bar.java
と Baz.java
どのように見えるかもしれません。これらは(この例で)の非常にシンプルなラッパークラスです int
, String
, 、 と boolean
. 。この時点まで、すべてがハンキーなドーリーです。の第9ラウンドを書いた後
class WhoCares {
@XmlAttribute
Whatever value;
/* 2 constructors */
/* 6 methods found in every one of these classes */
}
私は思った: 「ねえ、私はこれをどのように解決できるか知っています - 私はただ1つのレベルの抽象化が必要です!」 紹介 Wrapper<T>
:
abstract class Wrapper<T> {
@XmlAttribute
private T value;
Wrapper() {} // default ctor for JAXB
Wrapper(T value) {
this.value = value;
}
T getValue() {
return value;
}
// snip equals, hashCode, toString
}
今、実装する Foo
, 、私がする必要があるのは拡張することだけです Wrapper
, 、必要な工場の方法を実装してください。
class Foo extends Wrapper<String> {
// snip constructors
static Foo valueOf(String value) {
return new Foo(value);
}
}
そして、追加します @XmlSeeAlso({... Foo.class ...})
に Wrapper
の宣言。
- Pro:これはずっといいです。
- CON: Jaxbはこれらのオブジェクトをシリアル化しません。
任意の呼び出し JAXBContext.getInstance(Wrapper.class)
また JAXBContext.getInstance(Foo.class)
aのために失敗します NullPointerException
Jaxbの腸の奥深くに投げられた:
17:06:03,706 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/Redacted].[JAX-RS Servlet]] Servlet.service() for servlet JAX-RS Servlet threw exception: java.lang.NullPointerException
at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor.get(TransducedAccessor.java:165) [:2.2]
at com.sun.xml.bind.v2.runtime.property.AttributeProperty.<init>(AttributeProperty.java:87) [:2.2]
at com.sun.xml.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:104) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:179) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:166) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:534) [:2.2]
at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.<init>(SingleElementNodeProperty.java:101) [:2.2]
at sun.reflect.GeneratedConstructorAccessor49.newInstance(Unknown Source) [:1.6.0_24]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) [:1.6.0_24]
at java.lang.reflect.Constructor.newInstance(Constructor.java:513) [:1.6.0_24]
at com.sun.xml.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:124) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:179) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:166) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:330) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1140) [:2.2]
at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:154) [:2.2]
at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:121) [:2.2]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [:1.6.0_24]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [:1.6.0_24]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [:1.6.0_24]
at java.lang.reflect.Method.invoke(Method.java:597) [:1.6.0_24]
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:201) [:1.0.0.Final]
at javax.xml.bind.ContextFinder.find(ContextFinder.java:362) [:1.0.0.Final]
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:618) [:1.0.0.Final]
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:565) [:1.0.0.Final]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getStoredJAXBContext(AbstractJAXBProvider.java:189) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getJAXBContext(AbstractJAXBProvider.java:182) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getMarshaller(AbstractJAXBProvider.java:160) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getMarshaller(AbstractJAXBProvider.java:139) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:151) [:1.6]
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:306) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1310) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1223) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1213) [:1.6]
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:414) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699) [:1.6]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [:1.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:324) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.RetryFilter.doFilter(RetryFilter.java:109) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.AuthFilter.doFilter(AuthFilter.java:57) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:67) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [:6.0.0.Final]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:181) [:6.0.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285) [:1.1.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261) [:1.1.0.Final]
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:88) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:100) [:6.0.0.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) [:6.0.0.Final]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [:6.0.0.Final]
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) [:6.0.0.Final]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [:6.0.0.Final]
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:53) [:6.0.0.Final]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:362) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:654) [:6.0.0.Final]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:951) [:6.0.0.Final]
at java.lang.Thread.run(Thread.java:662) [:1.6.0_24]
私はすでにJAXBの実装をMetroからMoxyに切り替えようとしました(そして私はしました 実装が変更されたことを確認してください)しかし、同様のNPEはMoxyでスローされます:
17:46:48,481 SEVERE [com.sun.jersey.spi.container.ContainerResponse] Mapped exception to response: 500 (Internal Server Error): javax.ws.rs.WebApplicationException: javax.xml.bind.MarshalException
- with linked exception:
[Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: java.lang.NullPointerException]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:159) [:1.6]
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:306) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1310) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1223) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1213) [:1.6]
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:414) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699) [:1.6]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [:1.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:324) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.RetryFilter.doFilter(RetryFilter.java:109) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.AuthFilter.doFilter(AuthFilter.java:57) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:67) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [:6.0.0.Final]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:181) [:6.0.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285) [:1.1.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261) [:1.1.0.Final]
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:88) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:100) [:6.0.0.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) [:6.0.0.Final]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [:6.0.0.Final]
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) [:6.0.0.Final]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [:6.0.0.Final]
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:53) [:6.0.0.Final]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:362) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:654) [:6.0.0.Final]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:951) [:6.0.0.Final]
at java.lang.Thread.run(Thread.java:662) [:1.6.0_24]
Caused by: javax.xml.bind.MarshalException
- with linked exception:
[Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: java.lang.NullPointerException]
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:314) [:2.2.0.v20110202-r8913]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:179) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:157) [:1.6]
... 36 more
Caused by: Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: java.lang.NullPointerException
at org.eclipse.persistence.exceptions.XMLMarshalException.marshalException(XMLMarshalException.java:78) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.XMLMarshaller.marshal(XMLMarshaller.java:516) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:312) [:2.2.0.v20110202-r8913]
... 38 more
Caused by: java.lang.NullPointerException
at org.eclipse.persistence.oxm.record.OutputStreamRecord.outputStreamWrite(OutputStreamRecord.java:511) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.record.OutputStreamRecord.openStartElement(OutputStreamRecord.java:159) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.startElement(XPathNode.java:330) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshalSingleValue(XMLCompositeObjectMappingNodeValue.java:185) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshal(XMLCompositeObjectMappingNodeValue.java:116) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:104) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:60) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:322) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.marshalAttributes(TreeObjectBuilder.java:338) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.startElement(XPathNode.java:344) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshalSingleValue(XMLCompositeObjectMappingNodeValue.java:167) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshal(XMLCompositeObjectMappingNodeValue.java:116) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:104) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:60) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:322) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:325) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLAnyObjectMappingNodeValue.marshalSingleValue(XMLAnyObjectMappingNodeValue.java:154) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLAnyObjectMappingNodeValue.marshal(XMLAnyObjectMappingNodeValue.java:70) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:104) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:60) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:322) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:325) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.XMLMarshaller.marshal(XMLMarshaller.java:932) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.XMLMarshaller.marshal(XMLMarshaller.java:486) [:2.2.0.v20110202-r8913]
... 39 more
ボイラープレートを最小限に抑えて滞在しながら、必要なXMLを生成する方法はありますか ドライ?
解決
あなたが見ている問題は、メトロ(参照実装)と両方のバグによるものです Eclipselink Moxy JAXB実装。関連するMoxyバグは次のとおりです。
ユースケースについて注意すべきことの1つは、タイプの消去により、JaxB実装がバリュープロパティをタイプオブジェクトとして扱うことです。これは、元sの運用があなたのために機能することを意味しますが、除外事業は値を文字列として返します。これが、XSI:タイプ情報を維持するために@XMLElementを@XMLElementで注釈に付けた場合、次のとおりです。
Moxyの回避策
次のxmladapterを活用することにより、Moxyバグを回避します。
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class ObjectAdapter extends XmlAdapter<Object, Object> {
@Override
public Object unmarshal(Object v) throws Exception {
return v;
}
@Override
public Object marshal(Object v) throws Exception {
return v;
}
}
XMLアダプターは、次のようにプロパティに登録されています。
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlSeeAlso;
import javax.xml.bind.annotation.XmlTransient;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@XmlTransient
@XmlAccessorType(XmlAccessType.FIELD)
@XmlSeeAlso(Foo.class)
abstract class Wrapper<T> {
@XmlAttribute
@XmlJavaTypeAdapter(ObjectAdapter.class)
private T value;
Wrapper() {} // default ctor for JAXB
public Wrapper(T t) {
value = t;
}
}