Abstract: This paper introduces the concepts and services reference of Scene Access Interface（SAI），which is one of the specification of Extensible 3D（X3D），the principles and realization of two ways of interaction，Internal Interactions and External Interactions，between X3D scene and Java through SAI are also elaborated，two types of interactions are illustrated by two corresponding samples.The application results show that the interaction between X3D scene and Java through SAI is an effective interaction method.By integrating X3D with Java，developers can get the advantage of powerful logic control and web communication capability of Java over X3D to enhance the interactivity between X3D scene and user code，and construct more complex and powerful networked virtual reality system applications.

摘要： 介绍了X3D规范之一的场景访问接口（Scene Access Interface，SAI）的概念及其提供的功能服务，并介绍了X3D虚拟场景通过SAI和Java交互的两种方法的原理和实现过程：通过Script节点的方法和直接与外部程序交互的方法，并举例说明了两种交互方式。应用表明，虚拟场景通过SAI和Java的交互是一种行之有效的交互方法。通过X3D和Java的结合，开发人员能够获得Java功能强大的逻辑控制和网络通信能力以增强虚拟场景的交互性，构建功能更加强大的网络虚拟现实系统应用。