import java.util.Hashtable;

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class GlobalValues implements java.io.Serializable
{
    private static GlobalValues self = null;
    
    public static synchronized GlobalValues getRef()
    {
        if( self == null )
        {
            self = new GlobalValues();
        }
        return( self );
    }
    
    private Hashtable cache;

    private GlobalValues()
    {
        cache = new Hashtable( 15, 5 );
        // load your JDBC driver
    }

    public synchronized String get( String name ) 
    {
        Value value = (Value) cache.get( name );

        if( ( value == null ) || ( value.hasExpired() ) )
        {
            value = load( name );
            cache.put( name, value );
        }
        
        return( value.getValue() );
    }

    private Value load( String name ) 
    {
        Value value = null;
        
        try
        {
            Connection conn = DriverManager.getConnection( "your database" );
            String sql = "SELECT VALUE, EXPIRE FROM GLOBAL_VALUES WHERE NAME = '?'";
            PreparedStatement prep = conn.prepareStatement( sql );
            prep.setString( 1, name );
            ResultSet rset = prep.executeQuery();
            if( rset.next() )
            {
                String val = rset.getString( "VALUE" );
                long exp = rset.getInt( "EXPIRE" );
                value = new Value( val, exp );
            }
            rset.close();
            prep.close();
            conn.close();
        }
        catch( SQLException e )
        {
        }
        return( value );
    }

    class Value
    {
        private long time;
        private String value;
        private long expire;

        Value( String value, long expire )
        {
            this.value = value;
            this.expire = expire;
            time = System.currentTimeMillis();
        }

        String getValue()
        {
            return value;
        }

        boolean hasExpired()
        {
            if( expire != 0 )
            {
                if( ( System.currentTimeMillis() - time ) > expire )
                {
                    return true;
                }
            }
            return false;
        }
    } 
}