Bug 153896 Improve the performance of BIRT datetime-converting
The current datetime converting algorithm in birt.core, xml&flatfile ODA implementations are not efficient enough.This is because we use java's SimpleDateTimeFormatter to parse ISO8601 compatible date/time values. We should write our own datatime string parser for ISO8601 datetime format.
core/org.eclipse.birt.core/src/org/eclipse/birt/core/data/DataTypeUtil.java
double doubleValue = ( (Number) source ).doubleValue( );
			return new Double( doubleValue );
		}
		else if ( source instanceof Boolean )
		{
			if ( true == ( (Boolean) source ).booleanValue( ) )
				return new Double( 1d );
			return new Double( 0d );
		}
		else if ( source instanceof Date )
		{
			double doubleValue = ( (Date) source ).getTime( );
			return new Double( doubleValue );
		}
		else if ( source instanceof String )
		{
			try
			{
				return Double.valueOf( (String) source );
			}
			catch ( NumberFormatException e )
			{
				throw new BirtException( pluginId,
						ResourceConstants.CONVERT_FAILS,
						new Object[]{
								source.toString( ), "Double"
						},
						resourceBundle );
			}
		}