在预准备语句中绑定空变量

我发誓这曾经有效，但在这种情况下不是。我正在尝试匹配 col1、col2 和 col3，即使其中一个或多个为空。我知道，在某些语言中，我不得不诉诸于诸如.这里需要这样做吗？((? is null AND col1 is null) OR col1 = ?)

        PreparedStatement selStmt = getConn().prepareStatement(
                "SELECT     * " +
                "FROM       tbl1 " +
                "WHERE      col1 = ? AND col2 = ? and col3 = ?");
        try
        {
            int col = 1;
            setInt(selStmt, col++, col1);
            setInt(selStmt, col++, col2);
            setInt(selStmt, col++, col3);
            ResultSet rs = selStmt.executeQuery();
            try
            {
                while (rs.next())
                {
                   // process row
                }
            }
            finally
            {
                rs.close();
            }
        }
        finally
        {
            selStmt.close();
        }

   // Does the equivalient of stmt.setInt(col, i) but preserves nullness.
    protected  static void setInt(PreparedStatement stmt, int col, Integer i)
    throws SQLException
    {
        if (i == null)
            stmt.setNull(col, java.sql.Types.INTEGER);
        else
            stmt.setInt(col, i);
    }