JNI=java native interface, 为java应用程序提供调用本地方法的接口 The standard Java class library may not support the platform-dependent features needed by your application. You may already have a library or application written in another programming language and you wish to make it accessible to Java applications. You may want to implement a small portion of time-critical code in a lower-level programming language, such as assembly, and then have your Java application call these functions