In previous posts I have demonstrated how powerful JAXB's XmlAdapter can be when starting from domain objects. In this example I will demonstrate how to leverage an XmlAdapter when generating an object model from an XML schema. This post was inspired by an answer I gave to a question on Stack Overflow (feel free to up vote).
XMLSchema (format.xsd)
The following is the XML schema that will be used for this example. The interesting portion is a type called NumberCodeValueType . This type has a specified pattern requiring it be a seven digit number. This number can have leading zeros which would not be marshalled by JAXB's default conversion of numbers.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="root">
<xs:complexType>
<xs:sequence>
<xs:element name="number" type="NumberCodeValueType" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:simpleType name="NumberCodeValueType">
<xs:restriction base="xs:int">
<xs:pattern value="[0-7]{7}" />
</xs:restriction>
</xs:simpleType>
</xs:schema>
NumberFormatter
package blog.xmladapter.bindings;
public class NumberFormatter {
public static String printInt(Integer value) {
String result = String.valueOf(value);
for(int x=0, length = 7 - result.length(); x<length; x++) {
result = "0" + result;
}
return result;
}
public static Integer parseInt(String value) {
return Integer.valueOf(value);
}
}
bindings.xml
We will leverage a JAXB bindings file to reference the formatter:
<jxb:bindings xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:jxb="http://java.sun.com/xml/ns/jaxb" version="2.1">
<jxb:bindings schemaLocation="format.xsd">
<jxb:bindings node="//xs:element[@name='number']">
<jxb:property>
<jxb:baseType>
<jxb:javaType name="java.lang.Integer"
parseMethod="blog.xmladapter.bindings.NumberFormatter.parseInt"
printMethod="blog.xmladapter.bindings.NumberFormatter.printInt" />
</jxb:baseType>
</jxb:property>
</jxb:bindings>
</jxb:bindings>
</jxb:bindings>
XJC Call
The bindings file is referenced in the XJC call as:
xjc -d out -p blog.xmladapter.bindings -b bindings.xml format.xsd
Adapter1
This will cause an
XmlAdapter to be created that leverages the formatter:
package blog.xmladapter.bindings;
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class Adapter1 extends XmlAdapter<String, Integer> {
public Integer unmarshal(String value) {
return (blog.xmladapter.bindings.NumberFormatter.parseInt(value));
}
public String marshal(Integer value) {
return (blog.xmladapter.bindings.NumberFormatter.printInt(value));
}
}
Root
The
XmlAdapter will be referenced from the domain object using the
@XmlJavaTypeAdapter annotation:
package blog.xmladapter.bindings;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
"number"
})
@XmlRootElement(name = "root")
public class Root {
@XmlElement(required = true, type = String.class)
@XmlJavaTypeAdapter(Adapter1 .class)
protected Integer number;
public Integer getNumber() {
return number;
}
public void setNumber(Integer value) {
this.number = value;
}
}
Demo
Now if we run the following demo code:
package blog.xmladapter.bindings;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Root.class);
Root root = new Root();
root.setNumber(4);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(root, System.out);
}
}
Output
We will get the desired output:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
<number>0000004</number>
</root>
From http://blog.bdoughan.com/2011/08/xml-schema-to-java-generating.html
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