说明：  The production of this book required the efforts of many people, but two in particular deserve to be singled out for their diligent, sustained, and unselfish efforts. Sally Stickney, the book s principal editor, navigated me through that minefield called the English language and contributed greatly to the book s readability. Marc Young, whose talents as a technical editor are nothing short of amazing, was relentless in tracking down bugs, testing sample code, and verifying facts. Sally, Marc: This book is immeasurably better because of you. Thanks.