JAXB入门

引用

jaxb是一个读写xml的工具，还可以提供验证，不需要额外的jar

1. XSD sample

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.example.org/draft_2/"
	targetNamespace="http://www.example.org/draft_2/">

	<xs:complexType name="BaseCommonRefCType">
		<xs:sequence>
			<xs:element name="name">
				<xs:simpleType>
					<xs:restriction base="xs:string">
						<xs:minLength value="1" />
						<xs:maxLength value="64" />
					</xs:restriction>
				</xs:simpleType>
			</xs:element>
			<xs:element name="type" maxOccurs="1"
						minOccurs="0">
				<xs:simpleType>
					<xs:restriction base="xs:string">
						<xs:minLength value="1" />
						<xs:maxLength value="64" />
						<xs:enumeration value="filter" />
						<xs:enumeration value="nzload" />
						<xs:enumeration value="db_system" />
											<xs:enumeration value="repetition_group" />
						<xs:enumeration value="system_path" />
						<xs:enumeration value="record" />
						<xs:enumeration value="report" />
						<xs:enumeration value="mapping" />
						<xs:enumeration value="table" />
						<xs:enumeration value="cob" />
						<xs:enumeration value="file_container" />
						<xs:enumeration value="node" />
						<xs:enumeration value="instance" />
						<xs:enumeration value="stage" />
						<xs:enumeration value="java_config" />
						<xs:enumeration value="business_date" />
						<xs:enumeration value="matrix" />
						<xs:enumeration value="database" />
						<xs:enumeration value="file_pattern" />
						<xs:enumeration value="gemfire_region" />
						<xs:enumeration value="task" />
						<xs:enumeration value="config_file" />
						<xs:enumeration value="dataflow" />
						<xs:enumeration value="ems" />
						<xs:enumeration value="workflow" />
					</xs:restriction>
				</xs:simpleType>
			</xs:element>

		</xs:sequence>
	</xs:complexType>
</xs:schema>

2. 根据xsd生成java类

xjc -p com.wilson test.xsd -d   src

3. Sample class for retrieving classes from xml

public class JAXBUtil {
	private static final Log logger = LogFactory.getLog(JAXBUtil.class.getName());

	public static YourClass retrieveObjectFromXML(File xml, URL xsdURL) {
		ProcessLifeCycle lifeCycle = null;
		JAXBContext jaxbContext;
		ValidationEventCollector vec = new ValidationEventCollector();

		try {
			jaxbContext = JAXBContext.newInstance(YourClass.class);
			Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
			
			

			
			unmarshaller.setSchema(SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(xsdURL));
			unmarshaller.setEventHandler(vec);
			lifeCycle = (ProcessLifeCycle) unmarshaller.unmarshal(xml);

		} catch (JAXBException e) {
			logger.error("", e);
		} catch (SAXException e) {
			logger.error("", e);
		} finally {
			if (vec != null && vec.hasEvents()) {
				for (ValidationEvent ve : vec.getEvents()) {
					String msg = ve.getMessage();
					ValidationEventLocator vel = ve.getLocator();
					int line = vel.getLineNumber();
					int column = vel.getColumnNumber();
					throw new RuntimeException("Can't unmarshal the XML file, error message: " + " At line " + line + ", column " + column + ": "
							+ msg);
				}
			}
		}
		return lifeCycle;
	}
}