The Java EE 5 Tutorial

JAXB Examples

The sections that follow provide instructions for using the example Java applications that are included in the tut-install/javaeetutorial5/examples/jaxb/ directory. These examples demonstrate and build upon key JAXB features and concepts. Follow these procedures in the order presented.

After reading this section, you should feel comfortable enough with JAXB that you can:

• Generate JAXB Java classes from an XML schema

• Use schema-derived JAXB classes to unmarshal and marshal XML content in a Java application

• Create a Java content tree from scratch using schema-derived JAXB classes

• Validate XML content during unmarshalling and at runtime

• Customize JAXB schema-to-Java bindings

This chapter describes three sets of examples:

• The Basic examples (Modify Marshal, Unmarshal Validate) demonstrate basic JAXB concepts like unmarshalling, marshalling, and validating XML content using default settings and bindings.

• The Customize examples (Customize Inline, Datatype Converter, External Customize) demonstrate various ways of customizing the default binding of XML schemas to Java objects.

• The Java-to-Schema examples show how to use annotations to map Java classes to XML schema.

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  Note - The Basic and Customize examples are based on a Purchase Order scenario. Each uses an XML document, po.xml, written against an XML schema, po.xsd. These documents are derived from the W3C XML Schema Part 0: Primer, edited by David C. Fallside.

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The Basic and Customize example directories contain several base files:

• po.xsd is the XML schema you will use as input to the JAXB binding compiler, and from which schema-derived JAXB Java classes will be generated. For the Customize Inline and Datatype Converter examples, this file contains inline binding customizations.

• po.xml is the Purchase Order XML file containing sample XML content, and is the file you will unmarshal into a Java content tree in each example. This file is almost exactly the same in each example, with minor content differences to highlight different JAXB concepts.

• Main.java is the main Java class for each example.

• build.xml is an Ant project file provided for your convenience. Use the Ant tool to generate, compile, and run the schema-derived JAXB classes automatically. The build.xml file varies across the examples.

• MyDatatypeConverter.java in the inline-customize example is a Java class used to provide custom data type conversions.

• binding.xjb in the External Customize example is an external binding declarations file that is passed to the JAXB binding compiler to customize the default JAXB bindings.

Table 17-9, Table 17-10, and Table 17-11 briefly describe the Basic, Customize, and Java-to-Schema JAXB examples.

Table 17-9 Basic JAXB Examples

Table 17-10 Customize JAXB Examples

Table 17-11 Java-to-Schema JAXB Examples

JAXB Compiler Options

The JAXB XJC schema binding compiler transforms, or binds, a source XML schema to a set of JAXB content classes in the Java programming language. The compiler, xjc, is provided in two flavors in the Application Server: xjc.sh (Solaris/Linux) and xjc.bat (Windows). Both xjc.sh and xjc.bat take the same command-line options. You can display quick usage instructions by invoking the scripts without any options, or with the -help switch. The syntax is as follows:

xjc [-options ...] schema

The xjc command line options are as follows:

-nv

Do not perform strict validation of the input schema or schemas. By default, xjc performs strict validation of the source schema before processing. Note that this does not mean the binding compiler will not perform any validation; it simply means that it will perform less-strict validation.

-extension

By default, the XJC binding compiler strictly enforces the rules outlined in the Compatibility chapter of the JAXB Specification. In the default (strict) mode, you are also limited to using only the binding customizations defined in the specification. By using the -extension switch, you will be allowed to use the JAXB Vendor Extensions.

-b file

Specify one or more external binding files to process. (Each binding file must have its own -b switch.) The syntax of the external binding files is extremely flexible. You may have a single binding file that contains customizations for multiple schemas or you can break the customizations into multiple bindings files. In addition, the ordering of the schema files and binding files on the command line does not matter.

-d dir

By default, xjc will generate Java content classes in the current directory. Use this option to specify an alternate output directory. The directory must already exist; xjc will not create it for you.

-p package

Specify an alternate output directory. By default, the XJC binding compiler will generate the Java content classes in the current directory. The output directory must already exist; the XJC binding compiler will not create it for you.

-proxy proxy

Specify the HTTP/HTTPS proxy. The format is [user[:password]@]proxyHost[:proxyPort]. The old -host and -port options are still supported by the Reference Implementation for backwards compatibility, but they have been deprecated.

-classpath arg

Specify where to find client application class files used by the <jxb:javaType> and <xjc:superClass> customizations.

-catalog file

Specify catalog files to resolve external entity references. Supports TR9401, XCatalog, and OASIS XML Catalog format. For more information, see the XML Entity and URI Resolvers document or examine the catalog-resolver sample application.

-readOnly

Force the XJC binding compiler to mark the generated Java sources read-only. By default, the XJC binding compiler does not write-protect the Java source files it generates.

-npa

Suppress the generation of package level annotations into **/package-info.java. Using this switch causes the generated code to internalize those annotations into the other generated classes.

-xmlschema

Treat input schemas as W3C XML Schema (default). If you do not specify this switch, your input schemas will be treated as W3C XML Schema.

-quiet

Suppress compiler output, such as progress information and warnings.

-help

Display a brief summary of the compiler switches.

-version

Display the compiler version information.

-Xlocator

Enable source location support for generated code.

-Xsync-methods

Generate accessor methods with the synchronized keyword.

-mark-generated

Mark the generated code with the -@javax.annotation.Generated annotation.

JAXB Schema Generator Option

The JAXB Schema Generator, schemagen, creates a schema file for each namespace referenced in your Java classes. The schema generator can be launched using the appropriate schemagen shell script in the bin directory for your platform. The schema generator processes Java source files only. If your Java sources reference other classes, those sources must be accessible from your system CLASSPATH environment variable, otherwise errors will occur when the schema is generated. There is no way to control the name of the generated schema files.

You can display quick usage instructions by invoking the scripts without any options, or with the -help option. The syntax is as follows:

schemagen [-d path] [java-source-files]

The -d path option specifies the location of the processor- and javac-generated class files.

About the Schema-to-Java Bindings

When you run the JAXB binding compiler against the po.xsd XML schema used in the basic examples (Unmarshal Read, Modify Marshal, Unmarshal Validate), the JAXB binding compiler generates a Java package named primer.po containing 11 classes, making a total of 12 classes in each of the basic examples, as described in Table 17-12.

Table 17-12 Schema-Derived JAXB Classes in the Basic Examples

Note - You should never directly use the generated implementation classes (*Impl.java in the packagename/impl/ directory). These classes cannot be referenced directly because the class names in this directory are not standardized by the JAXB specification. The ObjectFactory method is the only portable means to create an instance of a schema-derived interface. There is also an ObjectFactory.newInstance(Class JAXBinterface) method that enables you to create instances of interfaces.

These classes and their specific bindings to the source XML schema for the basic examples are described in Table 17-13. .

Table 17-13 Schema-to-Java Bindings for the Basic Examples

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:element name="purchaseOrder" type="PurchaseOrderType"/>

<xsd:element name="comment" type="xsd:string"/>

<xsd:complexType name="PurchaseOrderType">
 <xsd:sequence>
 <xsd:element name="shipTo" type="USAddress"/>
 <xsd:element name="billTo" type="USAddress"/>
 <xsd:element ref="comment" minOccurs="0"/>
 <xsd:element name="items" type="Items"/>
 </xsd:sequence>
 <xsd:attribute name="orderDate" type="xsd:date"/>
</xsd:complexType>

<xsd:complexType name="USAddress">
 <xsd:sequence>
 <xsd:element name="name" type="xsd:string"/>
 <xsd:element name="street" type="xsd:string"/>
 <xsd:element name="city" type="xsd:string"/>
 <xsd:element name="state" type="xsd:string"/>
 <xsd:element name="zip" type="xsd:decimal"/>
 </xsd:sequence>
<xsd:attribute name="country" type="xsd:NMTOKEN" fixed="US"/>
</xsd:complexType>

<xsd:complexType name="Items">
 <xsd:sequence>
 <xsd:element name="item" minOccurs="1" maxOccurs="unbounded">

<xsd:complexType>
 <xsd:sequence>
 <xsd:element name="productName" type="xsd:string"/>
 <xsd:element name="quantity">
 <xsd:simpleType>
 <xsd:restriction base="xsd:positiveInteger">
 <xsd:maxExclusive value="100"/>
 </xsd:restriction>
 </xsd:simpleType>
 </xsd:element>
 <xsd:element name="USPrice" type="xsd:decimal"/>
 <xsd:element ref="comment" minOccurs="0"/>
 <xsd:element name="shipDate" type="xsd:date" minOccurs="0"/>
 </xsd:sequence>
 <xsd:attribute name="partNum" type="SKU" use="required"/>
</xsd:complexType>

</xsd:element>
 </xsd:sequence>
</xsd:complexType>

<!-- Stock Keeping Unit, a code for identifying products -->

<xsd:simpleType name="SKU">
 <xsd:restriction base="xsd:string">
 <xsd:pattern value="\d{3}-[A-Z]{2}"/>
 </xsd:restriction>
</xsd:simpleType>

</xsd:schema>

Schema-Derived JAXB Classes

The sections that follow briefly explain the functions of the following individual classes generated by the JAXB binding compiler for the Basic examples:

• Comment Class

• Items Class

• ObjectFactory Class

• PurchaseOrder Class

• PurchaseOrderType Class

• USAddress Class

Comment Class

In Comment.java:

• The Comment class is part of the primer.po package.

• Comment is a public interface that extends javax.xml.bind.Element.

• Content in instantiations of this class binds to the XML schema element named comment.

• The getValue() and setValue() methods are used to get and set strings representing XML comment elements in the Java content tree.

Items Class

In Items.java:

• The Items class is part of the primer.po package.

• The class provides public interfaces for Items and ItemType.

• Content in instantiations of this class binds to the XML ComplexTypes Items and its child element ItemType.

• Item provides the getItem() method.

• ItemType provides methods for:

  • getPartNum();

  • setPartNum(String value);

  • getComment();

  • setComment(java.lang.String value);

  • getUSPrice();

  • setUSPrice(java.math.BigDecimal value);

  • getProductName();

  • setProductName(String value);

  • getShipDate();

  • setShipDate(java.util.Calendar value);

  • getQuantity();

  • setQuantity(java.math.BigInteger value);

ObjectFactory Class

In ObjectFactory.java:

• The ObjectFactory class is part of the primer.po package.

• ObjectFactory provides factory methods for instantiating Java interfaces representing XML content in the Java content tree.

• Method names are generated by concatenating:

  • The string constant create.

  • If the Java content interface is nested within another interface, then the concatenation of all outer Java class names.

  • The name of the Java content interface.

    For example, in this case, for the Java interface primer.po.Items.ItemType, ObjectFactory creates the method createItemsItemType().

PurchaseOrder Class

In PurchaseOrder.java:

• The PurchaseOrder class is part of the primer.po package.

• PurchaseOrder is a public interface that extends javax.xml.bind.Element and primer.po.PurchaseOrderType.

• Content in instantiations of this class binds to the XML schema element named purchaseOrder.

PurchaseOrderType Class

In PurchaseOrderType.java:

• The PurchaseOrderType class is part of the primer.po package.

• Content in instantiations of this class binds to the XML schema child element named PurchaseOrderType.

• PurchaseOrderType is a public interface that provides the following methods:

  • getItems();

  • setItems(primer.po.Items value);

  • getOrderDate();

  • setOrderDate(java.util.Calendar value);

  • getComment();

  • setComment(java.lang.String value);

  • getBillTo();

  • setBillTo(primer.po.USAddress value);

  • getShipTo();

  • setShipTo(primer.po.USAddress value);

USAddress Class

In USAddress.java:

• The USAddress class is part of the primer.po package.

• Content in instantiations of this class binds to the XML schema element named USAddress.

• USAddress is a public interface that provides the following methods:

  • getState();

  • setState(String value);

  • getZip();

  • setZip(java.math.BigDecimal value);

  • getCountry();

  • setCountry(String value);

  • getCity();

  • setCity(String value);

  • getStreet();

  • setStreet(String value);

  • getName();

  • setName(String value);