如何让定义一个接口类，然后接口的方法直接调用！

public interface Connection {

    /**
     * Creates a <code>Statement</code> object for sending
     * SQL statements to the database.
     * SQL statements without parameters are normally
     * executed using <code>Statement</code> objects. If the same SQL statement 
     * is executed many times, it may be more efficient to use a 
     * <code>PreparedStatement</code> object.
     * <P>
     * Result sets created using the returned <code>Statement</code>
     * object will by default be type <code>TYPE_FORWARD_ONLY</code>
     * and have a concurrency level of <code>CONCUR_READ_ONLY</code>.
     *
     * @return a new default <code>Statement</code> object 
     * @exception SQLException if a database access error occurs
     */
    Statement createStatement() throws SQLException;//可以直接调用该接口方法，我知道里面做了许多处理，其实不是直接调用，调用了许多架包！