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| − | {{EclipseLink_UserGuide
| + | See http://www.eclipse.org/eclipselink/documentation/2.4/moxy/advanced_concepts007.htm |
| − | |info=y
| + | |
| − | |toc=y
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| − | |eclipselink=y
| + | |
| − | |eclipselinktype=MOXy
| + | |
| − | |api=y
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| − | |apis= * [http://www.eclipse.org/eclipselink/api/latest/javax/xml/bind/annotation/XmlTransformation.html XmlTransformation]
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| − | * [http://www.eclipse.org/eclipselink/api/latest/org/eclipse/persistence/oxm/annotations/XmlReadTransformer.html XmlReadTransformer]
| + | |
| − | * [http://www.eclipse.org/eclipselink/api/latest/org/eclipse/persistence/oxm/annotations/XmlWriteTransformer XmlWriteTransformer]
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| − | }}
| + | |
| − | =Transformation Mapping=
| + | |
| − | | + | |
| − | In many cases, you can use MOXy's '''@XmlTransformation''' annotation to give you considerably more control over the marshalling and unmarshalling of your objects. '''@XmlTransformation''' can be used to create a custom mapping where one or more XML nodes can be used to create value for the Java attribute.
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| − | | + | |
| − | To handle the custom requirements at marshal (write) and unmarshall (read) time, '''@XmlTransformation''' uses instances of '''org.eclipse.persistence.mappings.transformers''' (such as '''AttributeTransformer''' and '''FieldTransformer'''), providing a non-intrusive solution that avoids the need for domain objects to implement any 'special' interfaces.
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| − | | + | |
| − | For example, if you wanted to map the following XML to objects and combine the values of '''DATE''' and '''TIME''' into a single '''java.util.Date''' object, you can use an '''@XmlTransformation''':
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| − | | + | |
| − | <source lang="xml">
| + | |
| − | <ELEM_B>
| + | |
| − | <B_DATE>20100825</B_DATE>
| + | |
| − | <B_TIME>153000</B_TIME>
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| − | <NUM>123</NUM>
| + | |
| − | <C_DATE>20100825</C_DATE>
| + | |
| − | <C_TIME>154500</C_TIME>
| + | |
| − | </ELEM_B>
| + | |
| − | </source>
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| − | | + | |
| − | '''Note:''' Ordinarily, you would use '''@XmlAdapter'''. However:
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| − | * Although the '''DATE/TIME''' pairings are repeated throughout the document, the element name changes ''each time'' (such as '''B_DATE/B_TIME''', '''C_DATE/C_TIME''', and so on).
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| − | * Because each pairing is missing a grouping element, you would need to adapt ''the entire'' '''ElemB''' class.
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| − | | + | |
| − | Because of these issues, MOXy's transformation mapping is much easier to implement:
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| − | | + | |
| − | ==Example==
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| − | | + | |
| − | <source lang="Java">
| + | |
| − | package example;
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| − | | + | |
| − | import java.util.Date;
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| − |
| + | |
| − | import javax.xml.bind.annotation.*;
| + | |
| − | import org.eclipse.persistence.oxm.annotations.*;
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| − |
| + | |
| − | @XmlAccessorType(XmlAccessType.FIELD)
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| − | @XmlRootElement(name="ELEM_B")
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| − | public class ElemB {
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| − |
| + | |
| − | @XmlTransformation
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| − | @XmlReadTransformer(transformerClass=DateAttributeTransformer.class)
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| − | @XmlWriteTransformers({
| + | |
| − | @XmlWriteTransformer(xmlPath="B_DATE/text()", transformerClass=DateFieldTransformer.class),
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| − | @XmlWriteTransformer(xmlPath="B_TIME/text()", transformerClass=TimeFieldTransformer.class),
| + | |
| − | })
| + | |
| − | private Date bDate;
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| − |
| + | |
| − | @XmlElement(name="NUM")
| + | |
| − | private int num;
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| − |
| + | |
| − | @XmlTransformation
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| − | @XmlReadTransformer(transformerClass=DateAttributeTransformer.class)
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| − | @XmlWriteTransformers({
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| − | @XmlWriteTransformer(xmlPath="C_DATE/text()", transformerClass=DateFieldTransformer.class),
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| − | @XmlWriteTransformer(xmlPath="C_TIME/text()", transformerClass=TimeFieldTransformer.class),
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| − | })
| + | |
| − | private Date cDate;
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| − |
| + | |
| − | }
| + | |
| − | </source>
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| − | | + | |
| − | | + | |
| − | ==XML Read Transformer==
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| − | | + | |
| − | Use an XML ''read transformer'' to construct the object value from XML, as shown here:
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| − | | + | |
| − | <source lang="java">
| + | |
| − | package example;
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| − | | + | |
| − | import java.text.ParseException;
| + | |
| − | import java.text.SimpleDateFormat;
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| − |
| + | |
| − | import org.eclipse.persistence.internal.helper.DatabaseField;
| + | |
| − | import org.eclipse.persistence.mappings.foundation.AbstractTransformationMapping;
| + | |
| − | import org.eclipse.persistence.mappings.transformers.AttributeTransformer;
| + | |
| − | import org.eclipse.persistence.sessions.Record;
| + | |
| − | import org.eclipse.persistence.sessions.Session;
| + | |
| − |
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| − | public class DateAttributeTransformer implements AttributeTransformer {
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| − |
| + | |
| − | private AbstractTransformationMapping mapping;
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| − | private SimpleDateFormat yyyyMMddHHmmss = new SimpleDateFormat("yyyyMMddHHmmss");
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| − |
| + | |
| − | public void initialize(AbstractTransformationMapping mapping) {
| + | |
| − | this.mapping = mapping;
| + | |
| − | }
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| − |
| + | |
| − | public Object buildAttributeValue(Record record, Object instance, Session session) {
| + | |
| − | try {
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| − | String dateString = null;
| + | |
| − | String timeString = null;
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| − |
| + | |
| − | for(DatabaseField field : mapping.getFields()) {
| + | |
| − | if(field.getName().contains("DATE")) {
| + | |
| − | dateString = (String) record.get(field);
| + | |
| − | } else {
| + | |
| − | timeString = (String) record.get(field);
| + | |
| − | }
| + | |
| − | }
| + | |
| − | return yyyyMMddHHmmss.parseObject(dateString + timeString);
| + | |
| − | } catch(ParseException e) {
| + | |
| − | throw new RuntimeException(e);
| + | |
| − | }
| + | |
| − | }
| + | |
| − | | + | |
| − | }
| + | |
| − | </source>
| + | |
| − | | + | |
| − | | + | |
| − | ==XML Write Transformer(s)==
| + | |
| − | | + | |
| − | Use an XML ''write transformer'' to construct an XML value from the object.
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| − | | + | |
| − | Each transformation mapping may have multiple write transformers. In this example, you will need two:
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| − | | + | |
| − | * The first XML write transformer writes the year, month, and day in '''yyMMdd''' format:
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| − | | + | |
| − | <source lang="java">
| + | |
| − | package example;
| + | |
| − | | + | |
| − | import java.text.SimpleDateFormat;
| + | |
| − | import java.util.Date;
| + | |
| − |
| + | |
| − | import org.eclipse.persistence.mappings.foundation.AbstractTransformationMapping;
| + | |
| − | import org.eclipse.persistence.mappings.transformers.FieldTransformer;
| + | |
| − | import org.eclipse.persistence.sessions.Session;
| + | |
| − |
| + | |
| − | public class DateFieldTransformer implements FieldTransformer {
| + | |
| − |
| + | |
| − | private AbstractTransformationMapping mapping;
| + | |
| − | private SimpleDateFormat yyyyMMdd = new SimpleDateFormat("yyyyMMdd");
| + | |
| − |
| + | |
| − | public void initialize(AbstractTransformationMapping mapping) {
| + | |
| − | this.mapping = mapping;
| + | |
| − | }
| + | |
| − |
| + | |
| − | public Object buildFieldValue(Object instance, String xPath, Session session) {
| + | |
| − | Date date = (Date) mapping.getAttributeValueFromObject(instance);
| + | |
| − | return yyyyMMdd.format(date);
| + | |
| − | }
| + | |
| − |
| + | |
| − | }
| + | |
| − | </source>
| + | |
| − | | + | |
| − | *The second XML write transformer writes out the hour, minutes, and seconds in '''HHmmss''' format.
| + | |
| − | | + | |
| − | <source lang="java">
| + | |
| − | package example;
| + | |
| − | | + | |
| − | import java.text.SimpleDateFormat;
| + | |
| − | import java.util.Date;
| + | |
| − |
| + | |
| − | import org.eclipse.persistence.mappings.foundation.AbstractTransformationMapping;
| + | |
| − | import org.eclipse.persistence.mappings.transformers.FieldTransformer;
| + | |
| − | import org.eclipse.persistence.sessions.Session;
| + | |
| − |
| + | |
| − | public class TimeFieldTransformer implements FieldTransformer {
| + | |
| − |
| + | |
| − | private AbstractTransformationMapping mapping;
| + | |
| − | private SimpleDateFormat HHmmss = new SimpleDateFormat("HHmmss");
| + | |
| − |
| + | |
| − | public void initialize(AbstractTransformationMapping mapping) {
| + | |
| − | this.mapping = mapping;
| + | |
| − | }
| + | |
| − |
| + | |
| − | public Object buildFieldValue(Object instance, String xPath, Session session) {
| + | |
| − | Date date = (Date) mapping.getAttributeValueFromObject(instance);
| + | |
| − | return HHmmss.format(date);
| + | |
| − | }
| + | |
| − |
| + | |
| − | }
| + | |
| − | </source>
| + | |
