虚拟机是一种抽象化的计算机，通过在实际的计算机上仿真模拟各种计算机功能来实现的。Java虚拟机有自己完善的硬体架构，如处理器、堆栈、寄存器等，还具有相应的指令系统。Java虚拟机屏蔽了与具体操作系统平台相关的信息，使得Java程序只需生成在Java虚拟机上运行的目标代码（字节码），就可以在多种平台上不加修改地运行。(Virtual machine is an abstract computer, which is realized by simulating various computer functions on a real computer. Java virtual machine has its own perfect hardware architecture, such as processor, stack, registers, etc. It also has corresponding instruction system. The Java virtual machine masks the information related to the specific operating system platform, so that Java programs can run on a variety of platforms without modification only by generating the object code (bytecode) running on the Java virtual machine.)