Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2013 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.utils.xml;

import java.io.BufferedInputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.UnsupportedEncodingException;

/**

 * A set of methods to detect XML encoding. The class is able to autodetect

 * certain encodings, and it reads the XML header for the rest of encodings.

 * 

 * @author C?sar Mart?nez Izquierdo <cesar.martinez@iver.es>

 *

 */

public class XMLEncodingUtils {

        InputStream _is;

        /**

         * Creates a new XMLEncodingUtils object.

         * 

         * @param is An InputStream connected to the XML file to process.

         */

        public XMLEncodingUtils(InputStream is) {

                if (is == null)

                        throw new IllegalArgumentException();

                _is = is;

        }

        /**

         * Gets the encoding of the XML file.

         * 

         * The following encodings can be detected: UTF-32BE, UTF-32LE,

         * UTF-16BE, UTF-16-LE, UTF-8. The rest of the encodings are

         * read from the XML header.

         * 

         * @return Returns the encoding of the XML file, or null if the

         * encoding couldn't be correctly detected or read from the XML

         * header.

         */

        public String getEncoding() {

                int srcCount = 0;

                String enc=null;

                char[] srcBuf = new char[128];

                // read four bytes 

                int chk = 0;

                try {

                        while (srcCount < 4) {

                                int i = _is.read();

                                if (i == -1)

                                        break;

                                chk = (chk << 8) | i;

                                srcBuf[srcCount++] = (char) i;

                        }

                        if (srcCount == 4) {

                                switch (chk) {

                                case 0x00000FEFF :

                                        enc = "UTF-32BE";

                                        srcCount = 0;

                                        break;

                                case 0x0FFFE0000 :

                                        enc = "UTF-32LE";

                                        srcCount = 0;

                                        break;

                                case 0x03c :

                                        enc = "UTF-32BE";

                                        srcBuf[0] = '<';

                                        srcCount = 1;

                                        break;

                                case 0x03c000000 :

                                        enc = "UTF-32LE";

                                        srcBuf[0] = '<';

                                        srcCount = 1;

                                        break;

                                case 0x0003c003f :

                                        enc = "UTF-16BE";

                                        srcBuf[0] = '<';

                                        srcBuf[1] = '?';

                                        srcCount = 2;

                                        break;

                                case 0x03c003f00 :

                                        enc = "UTF-16LE";

                                        srcBuf[0] = '<';

                                        srcBuf[1] = '?';

                                        srcCount = 2;

                                        break;

                                case 0x03c3f786d :

                                        while (true) {

                                                int i = _is.read();

                                                if (i == -1)

                                                        break;

                                                srcBuf[srcCount++] = (char) i;

                                                if (i == '>') {

                                                        String s = new String(srcBuf, 0, srcCount);

                                                        int i0 = s.indexOf("encoding");

                                                        if (i0 != -1) {

                                                                while (s.charAt(i0) != '"'

                                                                        && s.charAt(i0) != '\'')

                                                                        i0++;

                                                                char deli = s.charAt(i0++);

                                                                int i1 = s.indexOf(deli, i0);

                                                                enc = s.substring(i0, i1);

                                                        }

                                                        break;

                                                }

                                        }

                                default :

                                        if ((chk & 0x0ffff0000) == 0x0FEFF0000) {

                                                enc = "UTF-16BE";

                                                srcBuf[0] =

                                                        (char) ((srcBuf[2] << 8) | srcBuf[3]);

                                                srcCount = 1;

                                        }

                                        else if ((chk & 0x0ffff0000) == 0x0fffe0000) {

                                                enc = "UTF-16LE";

                                                srcBuf[0] =

                                                        (char) ((srcBuf[3] << 8) | srcBuf[2]);

                                                srcCount = 1;

                                        }

                                        else if ((chk & 0x0ffffff00) == 0x0EFBBBF00) {

                                                enc = "UTF-8";

                                                srcBuf[0] = srcBuf[3];

                                                srcCount = 1;

                                        }

                                }

                        }

                }

                catch (IOException ex) {

                        return null;

                }

                return enc;

        }

        /**

         * Gets an InputStreamReader for the provided XML file.

         * The reader uses the right encoding, as specified in

         * the XML header (or autodetected). 

         * 

         * @return A reader which uses the right encoding, or null

         * if the encoding couldn't be correctly detected or read

         * from the XML header.

         */

        public InputStreamReader getReader() {

                String encoding = getEncoding();

                if (encoding==null)

                        return null;

                try {

                        return new InputStreamReader(_is, encoding);

                } catch (UnsupportedEncodingException e) {

                        return null;

                }

        }

        /**

         * Gets an InputStreamReader for the provided XML file.

         * The reader uses the right encoding, as specified in

         * the XML header (or autodetected).

         * 

         * @param is An InputStream connected to the XML file to process

         * @return A reader for the provided XML file.

         * @see getReader()

         */

        public static InputStreamReader getReader(InputStream is) {

                XMLEncodingUtils util = new XMLEncodingUtils(is);

                return util.getReader();

        }

        /**

         * Gets the character encoding of the XML file.

         * 

         * @param is An InputStream connected to the XML file to process

         * @see getEncoding()

         * @return The encoding of the file

         */

        public static String getEncoding(InputStream is) {

                XMLEncodingUtils util = new XMLEncodingUtils(is);

                return util.getEncoding();

        }

        /**

         * Gets an InputStreamReader for the provided XML file.

         * The reader uses the right encoding, as specified in

         * the XML header (or autodetected).

         * 

         * @param file The XML file to process

         * @return A reader for the provided XML file.

         * @see getReader()

         */

        public static InputStreamReader getReader(File file) throws FileNotFoundException {

                BufferedInputStream bs = new BufferedInputStream(new FileInputStream(file));

                XMLEncodingUtils util = new XMLEncodingUtils(bs);

                return util.getReader();

        }

        /**

         * Gets the character encoding of the XML file.

         * 

         * @param File The XML file to process

         * @see getEncoding()

         * @return The encoding of the file

         * @throws FileNotFoundException 

         */

        public static String getEncoding(File file) throws FileNotFoundException {

                BufferedInputStream bs = new BufferedInputStream(new FileInputStream(file));

                XMLEncodingUtils util = new XMLEncodingUtils(bs);

                return util.getEncoding();

        }

}