Using Marshaller and Unmarshaller

4.3.9.RELEASE Spring Framework 469 XmlMappingException Spring converts exceptions from the underlying OX mapping tool to its own exception hierarchy with the XmlMappingException as the root exception. As can be expected, these runtime exceptions wrap the original exception so no information will be lost. Additionally, the MarshallingFailureException and UnmarshallingFailureException provide a distinction between marshalling and unmarshalling operations, even though the underlying OX mapping tool does not do so. The OX Mapping exception hierarchy is shown in the following figure: OX Mapping exception hierarchy

21.3 Using Marshaller and Unmarshaller

Spring’s OXM can be used for a wide variety of situations. In the following example, we will use it to marshal the settings of a Spring-managed application as an XML file. We will use a simple JavaBean to represent the settings: public class Settings { private boolean fooEnabled; public boolean isFooEnabled { return fooEnabled; } public void setFooEnabled boolean fooEnabled { this .fooEnabled = fooEnabled; } } The application class uses this bean to store its settings. Besides a main method, the class has two methods: saveSettings saves the settings bean to a file named settings.xml , and loadSettings loads these settings again. A main method constructs a Spring application context, and calls these two methods. 4.3.9.RELEASE Spring Framework 470 import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import javax.xml.transform.stream.StreamResult; import javax.xml.transform.stream.StreamSource; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.oxm.Marshaller; import org.springframework.oxm.Unmarshaller; public class Application { private static final String FILE_NAME = settings.xml ; private Settings settings = new Settings; private Marshaller marshaller; private Unmarshaller unmarshaller; public void setMarshallerMarshaller marshaller { this .marshaller = marshaller; } public void setUnmarshallerUnmarshaller unmarshaller { this .unmarshaller = unmarshaller; } public void saveSettings throws IOException { FileOutputStream os = null; try { os = new FileOutputStreamFILE_NAME; this .marshaller.marshalsettings, new StreamResultos; } finally { if os = null { os.close; } } } public void loadSettings throws IOException { FileInputStream is = null; try { is = new FileInputStreamFILE_NAME; this .settings = Settings this .unmarshaller.unmarshal new StreamSourceis; } finally { if is = null { is.close; } } } public static void mainString[] args throws IOException { ApplicationContext appContext = new ClassPathXmlApplicationContext applicationContext.xml ; Application application = Application appContext.getBean application ; application.saveSettings; application.loadSettings; } } The Application requires both a marshaller and unmarshaller property to be set. We can do so using the following applicationContext.xml : beans bean id = application class = Application property name = marshaller ref = castorMarshaller property name = unmarshaller ref = castorMarshaller bean bean id = castorMarshaller class = org.springframework.oxm.castor.CastorMarshaller beans 4.3.9.RELEASE Spring Framework 471 This application context uses Castor, but we could have used any of the other marshaller instances described later in this chapter. Note that Castor does not require any further configuration by default, so the bean definition is rather simple. Also note that the CastorMarshaller implements both Marshaller and Unmarshaller , so we can refer to the castorMarshaller bean in both the marshaller and unmarshaller property of the application. This sample application produces the following settings.xml file: ?xml version=1.0 encoding=UTF-8? settings foo-enabled = false

21.4 XML Schema-based Configuration