com.cedarsolutions.util.JaxbUtils Maven / Gradle / Ivy
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* C E D A R
* S O L U T I O N S "Software done right."
* S O F T W A R E
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* Copyright (c) 2013 Kenneth J. Pronovici.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the Apache License, Version 2.0.
* See LICENSE for more information about the licensing terms.
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* Author : Kenneth J. Pronovici
* Language : Java 6
* Project : Common Java Functionality
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
package com.cedarsolutions.util;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;
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.bind.ValidationEvent;
import javax.xml.bind.util.ValidationEventCollector;
import javax.xml.transform.Source;
import javax.xml.transform.stream.StreamSource;
import com.cedarsolutions.exception.CedarRuntimeException;
/**
* JAXB utilities that operate on a cached JAXB context.
*
*
* The process of establishing a JAXB context can be pretty slow. So, we want
* to avoid having to do it more often than necessary. This class keeps an
* internal cache of contexts that have already been established. It also
* provides some utility methods to simplify marshalling and unmarshalling.
*
*
* @author Kenneth J. Pronovici
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public class JaxbUtils {
/** Singleton instance. */
private static JaxbUtils INSTANCE;
/** Map from class name to generated JAXB context. */
private Map contextMap = new HashMap();
/** Default constructor is private so class cannot be instantiated. */
private JaxbUtils() {
}
/** Get an instance of this class to use. */
public static synchronized JaxbUtils getInstance() {
if (INSTANCE == null) {
INSTANCE = new JaxbUtils();
}
return INSTANCE;
}
/**
* Get a JAXB context for the indicated class.
* @param className Name of the class to get a context for
* @return JAXB context for the class.
*/
public JAXBContext getJaxbContext(String className) {
try {
Class clazz = Class.forName(className);
return this.getJaxbContext(clazz);
} catch (Exception e) {
throw new CedarRuntimeException("Error obtaining JAXB context: " + e.getMessage(), e);
}
}
/**
* Get a JAXB context for the indicated class.
* @param clazz Class to get a context for.
* @return JAXB context for the class.
*/
public synchronized JAXBContext getJaxbContext(Class clazz) {
if (!this.contextMap.containsKey(clazz.getName())) {
try {
JAXBContext context = JAXBContext.newInstance(clazz);
this.contextMap.put(clazz.getName(), context);
} catch (Exception e) {
throw new CedarRuntimeException("Error obtaining JAXB context: " + e.getMessage(), e);
}
}
return this.contextMap.get(clazz.getName());
}
/**
* Marshal an object of type T, creating XML.
* @param Type of the object
* @param value Value to marshal.
* @return Generated XML.
*/
public String marshalDocument(T value) {
try {
JAXBContext context = this.getJaxbContext(value.getClass());
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);
StringWriter writer = new StringWriter();
marshaller.marshal(value, writer);
return writer.toString();
} catch (JAXBException e) {
throw new CedarRuntimeException("Error marshalling XML: " + e.getMessage(), e);
}
}
/**
* Unmarshal XML, creating an object of type T.
* @param Type of the object
* @param type Type of the object to unmarshal
* @param xml XML to use as source
* @return Object of type T, unmarshalled from the XML.
*/
public T unmarshalDocument(Class type, String xml) {
return unmarshalDocument(type, xml, true);
}
/**
* Unmarshal XML, creating an object of type T.
* @param Type of the object
* @param type Type of the object to unmarshal
* @param xml XML to use as source
* @param validate Whether to validate the unmarshalling step
* @return Object of type T, unmarshalled from the XML.
*/
public T unmarshalDocument(Class type, String xml, boolean validate) {
try {
JAXBContext context = this.getJaxbContext(type);
StringReader reader = new StringReader(xml);
Source source = new StreamSource(reader);
Unmarshaller unmarshaller = context.createUnmarshaller();
// If an adapter fails, we don't get an unmarshal exception.
// Instead, we have to register and interrogate a handler.
// See also: http://java.net/jira/browse/JAXB-537
ValidationEventCollector eventHandler = new ValidationEventCollector();
unmarshaller.setEventHandler(eventHandler);
JAXBElement element = unmarshaller.unmarshal(source, type);
if (validate) {
if (eventHandler.hasEvents()) {
StringBuffer buffer = new StringBuffer();
buffer.append("Error unmarshalling XML: found validation error(s)");
for (ValidationEvent event : eventHandler.getEvents()) {
buffer.append("\n\t -> ");
buffer.append(event.getMessage());
}
throw new CedarRuntimeException(buffer.toString());
}
}
return element.getValue();
} catch (JAXBException e) {
throw new CedarRuntimeException("Error unmarshalling XML: " + e.getMessage(), e);
}
}
}