如何使用 MOXy 绑定文件处理 java.util.Date

Question

一般来说，我对 MOXy 和 JaxB 很陌生，并且面临 java.util.Date 转换的问题。

我正在使用映射文件将 XML 文件（我无法控制）解组为对象（我既不能手动注释现有类，也不能更改它们）。

我的 XML 映射文件如下所示：

<?xml version="1.0"?>
<xml-bindings 
        xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
        version="2.1">
    <java-types>
        <java-type name="Observation">
            <xml-type prop-order="date theoricalTime ci ch cr type" />
            <java-attributes>
                <xml-element java-attribute="date" xml-path="Date/text()" />
                <xml-element java-attribute="theoricalTime" xml-path="TheoricalTime/text()" />
                <xml-element java-attribute="ci" xml-path="CIPR/text()" />
                <xml-element java-attribute="ch" xml-path="CHPR/text()" />
                <xml-element java-attribute="cr" xml-path="CRPR/text()" />
                <xml-element java-attribute="type" xml-path="Type/text()" />
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

在我要编组到的类中，属性“date”和“theoricalTime”的类型为 java.util.Date。

我编组的 xml 中的值是具有这种格式的字符串：“dd/MM/yyyy HH:mm:ss”（“05/01/2012 16:36:24”）。我还有一些只有时间值“HH:mm:ss”（“14:17:33”）的字段。

这是我在解组文件时得到的堆栈跟踪：

Exception in thread "main" Local Exception Stack: 
Exception [EclipseLink-3002] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.ConversionException
Exception Description: The object [22/01/2009 20:56:29], of class [class java.lang.String], from mapping [org.eclipse.persistence.oxm.mappings.XMLDirectMapping[date-->Date/text()]] with descriptor [XMLDescriptor(Observation --> [DatabaseTable(Observation)])], could not be converted to [class java.util.Calendar].
    at org.eclipse.persistence.exceptions.ConversionException.incorrectDateTimeFormat(ConversionException.java:127)
    at org.eclipse.persistence.exceptions.ConversionException.incorrectDateTimeFormat(ConversionException.java:133)
    at org.eclipse.persistence.internal.oxm.XMLConversionManager.convertStringToXMLGregorianCalendar(XMLConversionManager.java:703)
    at org.eclipse.persistence.internal.oxm.XMLConversionManager.convertStringToDate(XMLConversionManager.java:1111)
    at org.eclipse.persistence.internal.oxm.XMLConversionManager.convertObjectToUtilDate(XMLConversionManager.java:804)
    at org.eclipse.persistence.internal.oxm.XMLConversionManager.convertObject(XMLConversionManager.java:165)
    at org.eclipse.persistence.internal.databaseaccess.DatasourcePlatform.convertObject(DatasourcePlatform.java:160)
    at org.eclipse.persistence.oxm.mappings.XMLDirectMapping.getAttributeValue(XMLDirectMapping.java:293)
    at org.eclipse.persistence.internal.oxm.XMLDirectMappingNodeValue.endElement(XMLDirectMappingNodeValue.java:182)
    at org.eclipse.persistence.oxm.record.UnmarshalRecord.endElement(UnmarshalRecord.java:823)
    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:601)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1774)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2930)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
    at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:140)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
    at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
    at org.eclipse.persistence.internal.oxm.record.XMLReader.parse(XMLReader.java:157)
    at org.eclipse.persistence.internal.oxm.record.SAXUnmarshaller.unmarshal(SAXUnmarshaller.java:753)
    at org.eclipse.persistence.internal.oxm.record.SAXUnmarshaller.unmarshal(SAXUnmarshaller.java:333)
    at org.eclipse.persistence.internal.oxm.record.SAXUnmarshaller.unmarshal(SAXUnmarshaller.java:320)
    at org.eclipse.persistence.internal.oxm.record.SAXUnmarshaller.unmarshal(SAXUnmarshaller.java:280)
    at org.eclipse.persistence.oxm.XMLUnmarshaller.unmarshal(XMLUnmarshaller.java:306)
    at org.eclipse.persistence.jaxb.JAXBUnmarshaller.unmarshal(JAXBUnmarshaller.java:115)
    at Main.Test(Main.java:97)
    at Main.main(Main.java:35)

我的问题是：是否可以使用 MOXy 的外部元数据在映射文件内指定类型转换？如何使用上面指定的格式处理日期时间和时间并将它们映射到日期字段？

（我暗自希望 Blaise Doughan 正在读这篇文章。）

提前感谢您的帮助！

Answer 1

下面演示了如何将 XmlAdapter 与 MOXy 的外部映射文档结合使用来实现您正在寻找的结果：

DateAdapter

由于您的日期/时间数据采用以下格式dd/MM/yyyy HH:mm:ss 您将需要使用 XmlAdapter，如下所示：

package forum8745305;

import java.text.SimpleDateFormat;
import java.util.Date;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class DateAdapter extends XmlAdapter<String, Date> {

    private SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");

    @Override
    public String marshal(Date v) throws Exception {
        return dateFormat.format(v);
    }

    @Override
    public Date unmarshal(String v) throws Exception {
        return dateFormat.parse(v);
    }

}

oxm.xml

这通常在您的域模型使用@XmlJavaTypeAdapter 注释，但由于您使用的是 MOXy 的外部元数据文档，因此您可以按如下方式指定它。我已在包级别指定它，以便它将应用于属于该包中的域类的 java.util.Date 类型的所有字段/属性：

<?xml version="1.0"?>
<xml-bindings 
        xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
        version="2.1"
        package-name="forum8745305">
    <xml-java-type-adapters>
        <xml-java-type-adapter value="forum8745305.DateAdapter" type="java.util.Date"/>
    </xml-java-type-adapters>
    <java-types>
        <java-type name="Observation">
            <xml-type prop-order="date theoricalTime ci ch cr type" />
            <xml-root-element/>
            <java-attributes>
                <xml-element java-attribute="date" xml-path="Date/text()"/>
                <xml-element java-attribute="theoricalTime" xml-path="TheoricalTime/text()" />
                <xml-element java-attribute="numeroTrain" xml-path="NumeroTrain/text()" />
                <xml-element java-attribute="ci" xml-path="CIPR/text()" />
                <xml-element java-attribute="ch" xml-path="CHPR/text()" />
                <xml-element java-attribute="cr" xml-path="CRPR/text()" />
                <xml-element java-attribute="type" xml-path="Type/text()" />
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

观察

基于您的问题，下面是您的域类可能的样子：

package forum8745305;

import java.util.Date;

public class Observation {

    private Date date;
    private Date theoricalTime;
    private String numeroTrain;
    private String ci;
    private String ch;
    private String cr;
    private String type;

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public Date getTheoricalTime() {
        return theoricalTime;
    }

    public void setTheoricalTime(Date theoricalTime) {
        this.theoricalTime = theoricalTime;
    }

    public String getNumeroTrain() {
        return numeroTrain;
    }

    public void setNumeroTrain(String numeroTrain) {
        this.numeroTrain = numeroTrain;
    }

    public String getCi() {
        return ci;
    }

    public void setCi(String ci) {
        this.ci = ci;
    }

    public String getCh() {
        return ch;
    }

    public void setCh(String ch) {
        this.ch = ch;
    }

    public String getCr() {
        return cr;
    }

    public void setCr(String cr) {
        this.cr = cr;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

}

演示

以下代码可用于运行示例：

package forum8745305;

import java.io.File;
import java.util.HashMap;
import java.util.Map;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

import org.eclipse.persistence.jaxb.JAXBContextFactory;

public class Demo {

    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>(1);
        properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, "forum8745305/oxm.xml");
        JAXBContext jc = JAXBContext.newInstance(new Class[] {Observation.class}, properties);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum8745305/input.xml");
        Observation observation = (Observation) unmarshaller.unmarshal(xml);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(observation, System.out);
    }

}

输入/输出

<?xml version="1.0" encoding="UTF-8"?>
<observation>
    <Date>05/01/2012 16:36:24</Date>
    <TheoricalTime>01/02/2012 12:34:45</TheoricalTime>
</observation>

了解更多信息

• <一href="http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html" rel="noreferrer">http://blog.bdoughan.com/2011/05/specifying -eclipselink-moxy-as-your.html
• http://blog.bdoughan.com/2010/12/extending-jaxb -representing-annotations.html
• http://blog.bdoughan.com/search/label/XmlAdapter

UPDATE

您还可以在属性级别指定 XmlAdapters。这意味着如果您愿意，您可以为每个 Date 属性使用不同的 XmlAdapter。

<?xml version="1.0"?>
<xml-bindings 
        xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
        version="2.1"
        package-name="forum8745305">
    <java-types>
        <java-type name="Observation">
            <xml-type prop-order="date theoricalTime ci ch cr type" />
            <xml-root-element/>
            <java-attributes>
                <xml-element java-attribute="date" xml-path="Date/text()">
                    <xml-java-type-adapter value="forum8745305.DateAdapter"/>
                </xml-element>
                <xml-element java-attribute="theoricalTime" xml-path="TheoricalTime/text()">
                    <xml-java-type-adapter value="forum8745305.DateAdapter"/>
                </xml-element>
                <xml-element java-attribute="numeroTrain" xml-path="NumeroTrain/text()" />
                <xml-element java-attribute="ci" xml-path="CIPR/text()" />
                <xml-element java-attribute="ch" xml-path="CHPR/text()" />
                <xml-element java-attribute="cr" xml-path="CRPR/text()" />
                <xml-element java-attribute="type" xml-path="Type/text()" />
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>