XStreamUtil.java

/**
 *   GRANITE DATA SERVICES
 *   Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
 *
 *   This file is part of the Granite Data Services Platform.
 *
 *   Granite Data Services is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   Granite Data Services is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
 *   General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 *   USA, or see <http://www.gnu.org/licenses/>.
 */

package org.granite.builder.util;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringWriter;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.converters.reflection.Sun14ReflectionProvider;

/**
 * @author Franck WOLFF
 */
public class XStreamUtil {

	public static final String DEFAULT_CHARSET = "UTF-8";
	private static final String ENCODING_ATTR = "encoding=\""; 
	
	public static <T> T load(File file, Class<T> clazz) throws IOException {
		String charset = null;
		
		String xmlDeclaration = null;
		BufferedReader reader = null;
		try {
			reader = new BufferedReader(new FileReader(file));
			xmlDeclaration = reader.readLine();
		} finally {
			if (reader != null)
				reader.close();
		}
		
		if (xmlDeclaration != null && xmlDeclaration.startsWith("<?xml") && xmlDeclaration.endsWith("?>")) {
			int iEncoding = xmlDeclaration.indexOf(ENCODING_ATTR);
			if (iEncoding != -1) {
				int iEndEncoding = xmlDeclaration.indexOf('"', iEncoding + ENCODING_ATTR.length());
				if (iEndEncoding != -1)
					charset = xmlDeclaration.substring(iEncoding + ENCODING_ATTR.length(), iEndEncoding);
			}
		}
		
		return load(file, clazz, charset);
	}
	
	@SuppressWarnings("unchecked")
	public static <T> T load(File file, Class<T> clazz, String charset) throws IOException {
		Reader reader = null;
		try {
			if (charset != null)
				reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), charset));
			else
				reader = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
			
			XStream xs = new XStream(new Sun14ReflectionProvider());
			xs.processAnnotations(clazz);
			return (T)xs.fromXML(reader);
		} finally {
			if (reader != null)
				reader.close();
		}
	}
	
	public static void save(File file, Object o) throws IOException {
		save(file, o, null);
	}
	
	public static void save(File file, Object o, String charset) throws IOException {
		if (charset == null) 
			charset = DEFAULT_CHARSET;

		BufferedWriter writer = null;
		try {
			writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset));
			writer.write("<?xml version=\"1.0\" encoding=\"" + charset + "\"?>");
			writer.newLine();
			
			XStream xs = new XStream(new Sun14ReflectionProvider());
			xs.processAnnotations(o.getClass());
			xs.toXML(o, writer);
		} finally {
			if (writer != null)
				writer.close();
		}
	}
	
	public static String toString(Object o) {
		StringWriter writer = new StringWriter();
		XStream xs = new XStream(new Sun14ReflectionProvider());
		xs.processAnnotations(o.getClass());
		xs.toXML(o, writer);
		return writer.toString();
	}
}