use shared Calendar instance to converting Dates

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@663 f203690c-595d-4dc9-a70b-905162fa7fd2

2 files changed, 21 insertions, 5 deletions

diff --git a/src/java/com/healthmarketscience/jackcess/Column.java b/src/java/com/healthmarketscience/jackcess/Column.java
index 8e3033d..57df40e 100644
--- a/src/java/com/healthmarketscience/jackcess/Column.java
+++ b/src/java/com/healthmarketscience/jackcess/Column.java
@@ -601,12 +601,12 @@ public class Column implements Comparable<Column> {
     return _fixedDataOffset;
   }
 
-  protected Charset getCharset() {
+  Charset getCharset() {
     return getDatabase().getCharset();
   }
 
-  protected TimeZone getTimeZone() {
-    return getDatabase().getTimeZone();
+  Calendar getCalendar() {
+    return getDatabase().getCalendar();
   }
 
   /**
@@ -1179,7 +1179,7 @@ public class Column implements Comparable<Column> {
    */
   private long getToLocalTimeZoneOffset(long time)
   {
-    Calendar c = Calendar.getInstance(getTimeZone());
+    Calendar c = getCalendar();
     c.setTimeInMillis(time);
     return ((long)c.get(Calendar.ZONE_OFFSET) + c.get(Calendar.DST_OFFSET));
   }  
@@ -1192,7 +1192,7 @@ public class Column implements Comparable<Column> {
   {
     // getting from local time back to UTC is a little wonky (and not
     // guaranteed to get you back to where you started)
-    Calendar c = Calendar.getInstance(getTimeZone());
+    Calendar c = getCalendar();
     c.setTimeInMillis(time);
     // apply the zone offset first to get us closer to the original time
     c.setTimeInMillis(time - c.get(Calendar.ZONE_OFFSET));
diff --git a/src/java/com/healthmarketscience/jackcess/Database.java b/src/java/com/healthmarketscience/jackcess/Database.java
index d9fe435..2867587 100644
--- a/src/java/com/healthmarketscience/jackcess/Database.java
+++ b/src/java/com/healthmarketscience/jackcess/Database.java
@@ -46,6 +46,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Calendar;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.ConcurrentModificationException;
@@ -490,6 +491,8 @@ public class Database
   /** shared state used when enforcing foreign keys */
   private final FKEnforcer.SharedState _fkEnforcerSharedState =
     FKEnforcer.initSharedState();
+  /** Calendar for use interpreting dates/times in Columns */
+  private Calendar _calendar;
 
   /**
    * Open an existing Database.  If the existing file is not writeable, the
@@ -1063,6 +1066,8 @@ public class Database
       newTimeZone = getDefaultTimeZone();
     }
     _timeZone = newTimeZone;
+    // clear cached calendar when timezone is changed
+    _calendar = null;
   }    
 
   /**
@@ -1135,6 +1140,17 @@ public class Database
   }
 
   /**
+   * @usage _advanced_method_
+   */
+  Calendar getCalendar()
+  {
+    if(_calendar == null) {
+      _calendar = Calendar.getInstance(_timeZone);
+    }
+    return _calendar;
+  }
+
+  /**
    * @returns the current handler for reading/writing properties, creating if
    * necessary
    */