Pro XML Development with Java Technology 2006 phần 6 pptx

CHAPTER 6 ■ OBJECT BINDING WITH JAXB 171

Binding Catalog Schema to Java Classes

In this section, you will bind the catalog schema shown in Listing 6-6 to its Java content classes.

You’ll subsequently use the Java content classes to marshal and unmarshal the XML document

shown in Listing 6-7. You will run xjc from within Eclipse. Therefore, configure xjc as an external

tool in Eclipse, similar to the JAXB 1.0 project configuration. The only difference for the JAXB 2.0

project is that the xjc batch file Location field is set to the JAXB 2.0 xjc batch file. You set the envi￾ronment variables JAVA_HOME and JAXB_HOME similar to JAXB 1.0. Set JAXB_HOME for Chapter6-JAXB2.0

to C:\Sun\jwsdp-2.0\jaxb. To add the xjc configuration to the External Tools menu, select the

Common tab, and select the check box External Tools in the Display in Favorites menu area, as

shown in Figure 6-7.

To run the xjc compiler on the example schema, catalog.xsd, select the catalog.xsd file in the

Package Explorer and then select Run ➤ External Tools ➤ XJC. Schema-derived classes get generated in

the gen_source folder, as shown in Figure 6-12.

Figure 6-12. Schema-derived Java content classes generated by xjc

Java classes and interfaces are generated in the package generated by default. Fewer classes are

generated with JAXB 2.0 than with JAXB 1.0. For each xsd:complexType schema component, one

value class gets generated, instead of an interface and an implementation class. For example, for the

complex type catalogType, shown in Listing 6-33, the value class CatalogType.java gets generated.

Listing 6-33. The Complex Type catalogType

<xsd:complexType name="catalogType">

<xsd:sequence>

<xsd:element ref="journal" minOccurs="0" maxOccurs="unbounded"/>

</xsd:sequence>

<xsd:attribute name="section" type="xsd:string"/>

<xsd:attribute name="publisher" type="xsd:string"/>

</xsd:complexType>

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172 CHAPTER 6 ■ OBJECT BINDING WITH JAXB

The CatalogType.java class consists of getter and setter methods for each of the attributes of

the catalogType complex type. A getter method for the complex type journalType with the return

type List<JournalType> also gets generated. Listing 6-34 shows CatalogType.java.

Listing 6-34. CatalogType.java

package generated;

import java.util.ArrayList;

import java.util.List;

import javax.xml.bind.annotation.AccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlAttribute;

import javax.xml.bind.annotation.XmlType;

import generated.CatalogType;

import generated.JournalType;

@XmlAccessorType(AccessType.FIELD)

@XmlType(name = "catalogType", propOrder = {

"journal"

})

public class CatalogType {

protected List<JournalType> journal;

@XmlAttribute

protected String publisher;

@XmlAttribute

protected String section;

public List<JournalType> getJournal() {

if (journal == null) {

journal = new ArrayList<JournalType>();

}

return this.journal;

}

public String getPublisher() {

return publisher;

}

public void setPublisher(String value) {

this.publisher = value;

}

public String getSection() {

return section;

}

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CHAPTER 6 ■ OBJECT BINDING WITH JAXB 173

public void setSection(String value) {

this.section = value;

}

}

Similarly, the value class JournalType.java gets generated for the complex type journalType,

and the value class ArticleType.java gets generated for the complex type articleType. An

ObjectFactory.java factory class gets generated, which consists of the create methods for each of

the complex type and element declarations in the example schema. For example, the ObjectFactory

class method for the complex type catalogType is createCatalogType(), and its return type is

CatalogType. The ObjectFactory class method for the element catalog is

createCatalog(CatalogType), and its return type is JAXBElement<CatalogType>. Listing 6-35 shows

ObjectFactory.java.

Listing 6-35. ObjectFactory.java

package generated;

import javax.xml.bind.JAXBElement;

import javax.xml.bind.annotation.XmlElementDecl;

import javax.xml.bind.annotation.XmlRegistry;

import javax.xml.namespace.QName;

import generated.ArticleType;

import generated.CatalogType;

import generated.JournalType;

import generated.ObjectFactory;

@XmlRegistry

public class ObjectFactory {

private final static QName _Article_QNAME = new QName("", "article");

private final static QName _Journal_QNAME = new QName("", "journal");

private final static QName _Catalog_QNAME = new QName("", "catalog");

public ObjectFactory() {

}

public JournalType createJournalType() {

return new JournalType();

}

public ArticleType createArticleType() {

return new ArticleType();

}

public CatalogType createCatalogType() {

return new CatalogType();

}

@XmlElementDecl(namespace = "", name = "article")

public JAXBElement<ArticleType> createArticle(ArticleType value) {

return new JAXBElement<ArticleType>

(_Article_QNAME, ArticleType.class, null, value);

}

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