用JAXB保持干爽 [英] Staying DRY with JAXB

查看：124
本文介绍了用JAXB保持干爽的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在开发一些必须按以下格式序列化为XML的Java类：

I'm developing a number of Java classes that must serialize to XML in the following format:

<foo value="123"/>

<!-- or this -->
<bar value="abc"/>

<!-- or this -->
<baz value="true"/>

开头， Foo.java 看了类似这样的事情：

In the beginning, Foo.java looked something like this:

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
class Foo {
    @XmlAttribute
    String value;

    // snip constructors

    // snip methods
    // getValue
    // equals, hashCode, toString
    // static valueOf(String), static valueOf(int)
}

它没有多少想象力猜猜 Bar.java 和 Baz.java 可能是什么样子。这些是非常简单的包装类（在此示例中） int ， String ，以及布尔值。到目前为止，一切都是笨拙的。写完第九轮

It doesn't take much imagination to guess what Bar.java and Baz.java might look like. These are very simple wrapper classes for (in this example) int, String, and boolean. Up to this point, everything's hunky dory. After writing the ninth round of

class WhoCares {
    @XmlAttribute
    Whatever value;
    /* 2 constructors */
    /* 6 methods found in every one of these classes */
}

我想：嘿，我知道如何解决这个问题—我只需要一个级别的抽象！介绍 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
}

现在，要实现 Foo ，我需要做的就是扩展 Wrapper ，实现工厂方法我需要：

Now, to implement Foo, all I need to do is extend Wrapper, implement the factory methods I need:

class Foo extends Wrapper<String> {
    // snip constructors

    static Foo valueOf(String value) {
        return new Foo(value);
    }
}

并添加 @XmlSeeAlso （{... Foo.class ...}）到 Wrapper 的声明。


  • Pro：这样更好。

  • Con： JAXB不会序列化这些对象。

  • Pro: this is much nicer.
  • Con: JAXB won't serialize these objects.

对的任何调用JAXBContext.getInstance（Wrapper.class）或 JAXBContext.getInstance（Foo.class）由于 NullPointerException 因内部深处被抛出而失败of JAXB：

Any calls to JAXBContext.getInstance(Wrapper.class) or JAXBContext.getInstance(Foo.class) fail due to a NullPointerException thrown somewhere deep in the bowels of JAXB:

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]

我已经尝试过切换我的JAXB实现Metro到MOXy（我确实检查实施是否已更改）但是MOXy会抛出类似的NPE：

I've already tried switching my JAXB implementation from Metro to MOXy (and I did check that the implementation changed) but a similar NPE is thrown with MOXy:

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





有没有办法生成所需的XML，同时最小化样板并保留 DRY ？

Is there any way to produce the required XML while minimizing boilerplate and staying DRY?

推荐答案

您看到的问题是由Metro（参考实现）和 EclipseLink MOXy <中的错误造成的。 / a> JAXB实现。相关的MOXy错误是：

The issue you are seeing is due to bugs in both the Metro (reference implementation) and EclipseLink MOXy JAXB implementations. The relevant MOXy bug is:
  • https://bugs.eclipse.org/344539

有关您的用例的一点需要注意的是由于类型擦除，JAXB实现将把value属性视为Object类型。这意味着编组操作对您有用，但是解组操作会将值作为String返回。这就是为什么如果使用@XmlElement注释值字段，则会包含xsi：type信息以保留类型信息：

One thing to note about your use case is that due to type erasure, a JAXB implementation is going to treat the value property as type Object. This means that marshal operations will work for you, but an unmarshal operation will return the value as a String. This is why if the value field was annotated with @XmlElement that xsi:type information would be included to preserve the type information:

  • @XmlRootElement and <T extends Serializable> throws IllegalAnnotationExceptions

MOXy解决方法

通过利用以下XmlAdapter来解决MOXy错误：

You workaround the MOXy bug by leveraging the following XmlAdapter:

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适配器已在您的属性如下：

The XML Adapter is registered on your property as follows:

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;
    }

}

这篇关于用JAXB保持干爽的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

查看全文
相关文章
Java开发最新文章
热门教程
热门工具
登录 关闭
扫码关注1秒登录
发送“验证码”获取 | 15天全站免登陆