SimpleMarshallerImpl.java

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package gov.samhsa.acs.common.tool;

import gov.samhsa.acs.common.tool.exception.SimpleMarshallerException;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.namespace.QName;

/**
 * The Class MarshallerImpl.
 */
public class SimpleMarshallerImpl implements SimpleMarshaller {

	/*
	 * (non-Javadoc)
	 *
	 * @see gov.samhsa.acs.common.tool.Marshaller# marshall(java.lang.Object)
	 */
	@Override
	public String marshal(Object obj) throws SimpleMarshallerException {
		return marshal(obj, obj.getClass());
	}

	@Override
	public ByteArrayOutputStream marshalAsByteArrayOutputStream(Object obj)
			throws SimpleMarshallerException {
		try {
			final ByteArrayOutputStream marshalresult = new ByteArrayOutputStream();

			JAXBContext jaxbContext;
			jaxbContext = JAXBContext.newInstance(obj.getClass());
			final Marshaller marshaller = jaxbContext.createMarshaller();
			marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,
					Boolean.TRUE);
			marshaller.marshal(obj, marshalresult);

			return marshalresult;
		} catch (final Exception e) {
			throw new SimpleMarshallerException(e);
		}
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * gov.samhsa.acs.common.tool.SimpleMarshaller#marshalWithoutRootElement
	 * (java.lang.Object)
	 */
	@SuppressWarnings("unchecked")
	@Override
	public <T> String marshalWithoutRootElement(T obj)
			throws SimpleMarshallerException {
		final JAXBElement<T> wrappedJaxbElement = new JAXBElement<T>(new QName(
				obj.getClass().getSimpleName()), (Class<T>) obj.getClass(), obj);
		return marshal(wrappedJaxbElement, obj.getClass());
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * gov.samhsa.acs.common.tool.SimpleMarshaller#unmarshalFromXml(java.lang
	 * .Class, java.lang.String)
	 */
	@Override
	public <T> T unmarshalFromXml(Class<T> clazz, String xml)
			throws SimpleMarshallerException {
		JAXBContext context;
		try {
			context = JAXBContext.newInstance(clazz);
		} catch (final JAXBException e) {
			throw new SimpleMarshallerException(e);
		}
		return unmarshalFromXml(context, clazz, xml);
	}

	/**
	 * Marshal.
	 *
	 * @param <T>
	 *            the generic type
	 * @param obj
	 *            the obj
	 * @param contextClass
	 *            the context class
	 * @return the string
	 * @throws SimpleMarshallerException
	 *             the simple marshaller exception
	 */
	private <T> String marshal(Object obj, Class<T> contextClass)
			throws SimpleMarshallerException {
		JAXBContext context;
		String output;
		try {
			context = JAXBContext.newInstance(contextClass);

			// Create the marshaller, this is the nifty little thing that will
			// actually transform the object into XML
			final Marshaller marshaller = context.createMarshaller();

			// Create a stringWriter to hold the XML
			final StringWriter stringWriter = new StringWriter();

			// Marshal the javaObject and write the XML to the stringWriter
			marshaller.marshal(obj, stringWriter);
			output = stringWriter.toString();
		} catch (final JAXBException e) {
			throw new SimpleMarshallerException(e);
		}
		return output;
	}

	/**
	 * Unmarshal from xml.
	 *
	 * @param <T>
	 *            the generic type
	 * @param context
	 *            the context
	 * @param clazz
	 *            the clazz
	 * @param xml
	 *            the xml
	 * @return the t
	 * @throws SimpleMarshallerException
	 *             the simple marshaller exception
	 */
	@SuppressWarnings("unchecked")
	private <T> T unmarshalFromXml(JAXBContext context, Class<T> clazz,
			String xml) throws SimpleMarshallerException {
		Unmarshaller um;
		try {
			um = context.createUnmarshaller();
			final ByteArrayInputStream input = new ByteArrayInputStream(
					xml.getBytes("UTF-8"));
			return (T) um.unmarshal(input);
		} catch (JAXBException | UnsupportedEncodingException e) {
			throw new SimpleMarshallerException(e);
		}
	}
}