Add parse method that handles multiple patterns

bug 30674


git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@137989 13f79535-47bb-0310-9956-ffa450edef68

RELEASE-NOTES.txt

@@ -1,4 +1,4 @@
-$Id: RELEASE-NOTES.txt,v 1.32 2004/10/16 18:52:21 scolebourne Exp $
+$Id: RELEASE-NOTES.txt,v 1.33 2004/10/16 21:06:18 scolebourne Exp $
 
                         Commons Lang Package
                             Version 2.1
@@ -75,6 +75,7 @@ indexOfThrowable method untouched (see incompatible changes section)
 - NumberUtils - various string to number parsing methods added
 
 - DateUtils - methods added to compare dates in various ways
+           -- method to parse a date string using multiple patterns
 - FastDateFormat - extra formatting methods that take in a millisecond long value
                 -- additional static factory methods
 - StopWatch - new methods for split behaviour
@@ -113,6 +114,7 @@ BUG FIXES:
 29794  Add convenience format(long) methods to FastDateForma
 30328  HashCodeBuilder does not use the same values as Boolean (fixed as documentation)
 30334  New class proposal: CharacterEncoding
+30674  parseDate class from HttpClient's DateParser class
 30815  ArrayUtils.isEquals() throws ClassCastException when array1
 30929  Nestable.indexOfThrowable(Class)  uses Class.equals() to match
 31395  DateUtils.truncate oddity at the far end of the Date spectrum

src/java/org/apache/commons/lang/time/DateUtils.java

@@ -15,6 +15,9 @@
  */
 package org.apache.commons.lang.time;
 
+import java.text.ParseException;
+import java.text.ParsePosition;
+import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.Iterator;
@@ -31,7 +34,7 @@
  * @author <a href="mailto:ggregory@seagullsw.com">Gary Gregory</a>
  * @author Phil Steitz
  * @since 2.0
- * @version $Id: DateUtils.java,v 1.34 2004/10/16 17:43:05 scolebourne Exp $
+ * @version $Id: DateUtils.java,v 1.35 2004/10/16 21:06:18 scolebourne Exp $
  */
 public class DateUtils {
     
@@ -228,6 +231,42 @@ public static boolean isSameLocalTime(Calendar cal1, Calendar cal2) {
                 cal1.getClass() == cal2.getClass());
     }
 
+    //-----------------------------------------------------------------------
+    /**
+     * <p>Parses a string representing a date by trying a variety of different parsers.</p>
+     * 
+     * <p>The parse will try each parse pattern in turn.
+     * A parse is only deemed sucessful if it parses the whole of the input string.
+     * If no parse patterns match, a ParseException is thrown.</p>
+     * 
+     * @param str  the date to parse, not null
+     * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
+     * @return the parsed date
+     * @throws IllegalArgumentException if the date string or pattern array is null
+     * @throws ParseException if none of the date patterns were suitable
+     */
+    public static Date parseDate(String str, String[] parsePatterns) throws ParseException {
+        if (str == null || parsePatterns == null) {
+            throw new IllegalArgumentException("Date and Patterns must not be null");
+        }
+        
+        SimpleDateFormat parser = null;
+        ParsePosition pos = new ParsePosition(0);
+        for (int i = 0; i < parsePatterns.length; i++) {
+            if (i == 0) {
+                parser = new SimpleDateFormat(parsePatterns[0]);
+            } else {
+                parser.applyPattern(parsePatterns[i]);
+            }
+            pos.setIndex(0);
+            Date date = parser.parse(str, pos);
+            if (date != null && pos.getIndex() == str.length()) {
+                return date;
+            }
+        }
+        throw new ParseException("Unable to parse the date: " + str, -1);
+    }
+
     //-----------------------------------------------------------------------
     /**
      * <p>Round this date, leaving the field specified as the most

src/test/org/apache/commons/lang/time/DateUtilsTest.java

@@ -18,6 +18,7 @@
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Modifier;
 import java.text.DateFormat;
+import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.Date;
@@ -239,6 +240,40 @@ public void testIsSameLocalTime_Cal() {
         } catch (IllegalArgumentException ex) {}
     }
     
+    //-----------------------------------------------------------------------
+    public void testParseDate() throws Exception {
+        GregorianCalendar cal = new GregorianCalendar(1972, 11, 3);
+        String dateStr = "1972-12-03";
+        String[] parsers = new String[] {"yyyy'-'DDD", "yyyy'-'MM'-'dd", "yyyyMMdd"};
+        Date date = DateUtils.parseDate(dateStr, parsers);
+        assertEquals(cal.getTime(), date);
+        
+        dateStr = "1972-338";
+        date = DateUtils.parseDate(dateStr, parsers);
+        assertEquals(cal.getTime(), date);
+        
+        dateStr = "19721203";
+        date = DateUtils.parseDate(dateStr, parsers);
+        assertEquals(cal.getTime(), date);
+        
+        try {
+            DateUtils.parseDate("PURPLE", parsers);
+            fail();
+        } catch (ParseException ex) {}
+        try {
+            DateUtils.parseDate("197212AB", parsers);
+            fail();
+        } catch (ParseException ex) {}
+        try {
+            DateUtils.parseDate(null, parsers);
+            fail();
+        } catch (IllegalArgumentException ex) {}
+        try {
+            DateUtils.parseDate(dateStr, null);
+            fail();
+        } catch (IllegalArgumentException ex) {}
+    }
+    
     //-----------------------------------------------------------------------
     /**
      * Tests various values with the round method