source: josm/trunk/src/org/openstreetmap/josm/tools/FallbackDateParser.java@ 729

package org.openstreetmap.josm.tools;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;


/**
 * Handles a number of different date formats encountered in OSM. This is built
 * based on similar code in JOSM. This class is not threadsafe, a separate
 * instance must be created per thread.
 * 
 * @author Brett Henderson
 */
public class FallbackDateParser {
        
        private static final String[] formats = {
            "yyyy-MM-dd'T'HH:mm:ss'Z'",
                "yyyy-MM-dd'T'HH:mm:ssZ",
                "yyyy-MM-dd'T'HH:mm:ss",
                "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'",
                "yyyy-MM-dd'T'HH:mm:ss.SSSZ",
                "yyyy-MM-dd HH:mm:ss",
                "MM/dd/yyyy HH:mm:ss",
                "MM/dd/yyyy'T'HH:mm:ss.SSS'Z'",
                "MM/dd/yyyy'T'HH:mm:ss.SSSZ",
                "MM/dd/yyyy'T'HH:mm:ss.SSS",
                "MM/dd/yyyy'T'HH:mm:ssZ",
                "MM/dd/yyyy'T'HH:mm:ss",
                "yyyy:MM:dd HH:mm:ss"
        };
        
        
        private List<DateFormat> dateParsers;
        private int activeDateParser;
        
        
        /**
         * Creates a new instance.
         */
        public FallbackDateParser() {
                // Build a list of candidate date parsers.
                dateParsers = new ArrayList<DateFormat>(formats.length);
                for (int i = 0; i < formats.length; i++) {
                        dateParsers.add(new SimpleDateFormat(formats[i]));
                }
                
                // We haven't selected a date parser yet.
                activeDateParser = -1;
        }
        
        
        /**
         * Attempts to parse the specified date.
         * 
         * @param date
         *            The date to parse.
         * @return The date.
         * @throws ParseException
         *             Occurs if the date does not match any of the supported date
         *             formats.
         */
        public Date parse(String date) throws ParseException {
                String correctedDate;
                
                // Try to fix ruby's broken xmlschema - format
                // Replace this:
                // 2007-02-12T18:43:01+00:00
                // With this:
                // 2007-02-12T18:43:01+0000
                if (date.length() == 25 && date.charAt(22) == ':') {
                        correctedDate = date.substring(0, 22) + date.substring(23, 25);
                } else {
                        correctedDate = date;
                }
                
                // If we have previously successfully used a date parser, we'll try it
                // first.
                if (activeDateParser >= 0) {
                        try {
                                return dateParsers.get(activeDateParser).parse(correctedDate);
                        } catch (ParseException e) {
                                // The currently active parser didn't work, so we must clear it
                                // and find a new appropriate parser.
                                activeDateParser = -1;
                        }
                }
                
                // Try the date parsers one by one until a suitable format is found.
                for (int i = 0; i < dateParsers.size(); i++) {
                        try {
                                Date result;
                                
                                // Attempt to parse with the current parser, if successful we
                                // store its index for next time.
                                result = dateParsers.get(i).parse(correctedDate);
                                activeDateParser = i;
                                
                                return result;
                                
                        } catch (ParseException pe) {
                                // Ignore parsing errors and try the next pattern.
                        }
                }
                
                throw new ParseException("The date string (" + date + ") could not be parsed.", 0);
        }
}