Add some utility methods for handling Dates in an Access compatible manner. fixes issue #128

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@966 f203690c-595d-4dc9-a70b-905162fa7fd2

2 files changed, 32 insertions, 3 deletions

diff --git a/src/main/java/com/healthmarketscience/jackcess/DatabaseBuilder.java b/src/main/java/com/healthmarketscience/jackcess/DatabaseBuilder.java
index aa81855..c5e0252 100644
--- a/src/main/java/com/healthmarketscience/jackcess/DatabaseBuilder.java
+++ b/src/main/java/com/healthmarketscience/jackcess/DatabaseBuilder.java
@@ -20,6 +20,10 @@ import java.io.File;
 import java.io.IOException;
 import java.nio.channels.FileChannel;
 import java.nio.charset.Charset;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.TimeZone;
@@ -302,4 +306,28 @@ public class DatabaseBuilder
   {
     return new DatabaseBuilder(mdbFile).setFileFormat(fileFormat).create();
   }
+
+  /**
+   * Returns a SimpleDateFormat for the given format string which is
+   * configured with a compatible Calendar instance (see
+   * {@link #toCompatibleCalendar}).
+   */
+  public static SimpleDateFormat createDateFormat(String formatStr) {
+    SimpleDateFormat sdf = new SimpleDateFormat(formatStr);
+    toCompatibleCalendar(sdf.getCalendar());
+    return sdf;
+  }
+
+  /**
+   * Ensures that the given {@link Calendar} is configured to be compatible
+   * with how Access handles dates.  Specifically, alters the gregorian change
+   * (the java default gregorian change switches to julian dates for dates pre
+   * 1582-10-15, whereas Access uses <a href="https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar">proleptic gregorian dates</a>).
+   */
+  public static Calendar toCompatibleCalendar(Calendar cal) {
+    if(cal instanceof GregorianCalendar) {
+      ((GregorianCalendar)cal).setGregorianChange(new Date(Long.MIN_VALUE));
+    }
+    return cal;
+  }
 }
diff --git a/src/main/java/com/healthmarketscience/jackcess/impl/DatabaseImpl.java b/src/main/java/com/healthmarketscience/jackcess/impl/DatabaseImpl.java
index 26a7f1b..1984dc3 100644
--- a/src/main/java/com/healthmarketscience/jackcess/impl/DatabaseImpl.java
+++ b/src/main/java/com/healthmarketscience/jackcess/impl/DatabaseImpl.java
@@ -52,6 +52,7 @@ import com.healthmarketscience.jackcess.Cursor;
 import com.healthmarketscience.jackcess.CursorBuilder;
 import com.healthmarketscience.jackcess.DataType;
 import com.healthmarketscience.jackcess.Database;
+import com.healthmarketscience.jackcess.DatabaseBuilder;
 import com.healthmarketscience.jackcess.IndexBuilder;
 import com.healthmarketscience.jackcess.IndexCursor;
 import com.healthmarketscience.jackcess.PropertyMap;
@@ -702,10 +703,10 @@ public class DatabaseImpl implements Database
   /**
    * @usage _advanced_method_
    */
-  Calendar getCalendar()
-  {
+  Calendar getCalendar() {
     if(_calendar == null) {
-      _calendar = Calendar.getInstance(_timeZone);
+      _calendar = DatabaseBuilder.toCompatibleCalendar(
+          Calendar.getInstance(_timeZone));
     }
     return _calendar;
   }