1. Into Java (this reading is based on jdk1.7)

This reading is based on jdk1.7

1.1.java Virtual Machine categories and history:

Sun Classic/exact VM: The first commercially available Java virtual Machine in the world, Sun releases the JDK 1.0,java language for the first time to have a commercially available official operating environment, the virtual machine in this JDK is the Classic VM

Sun HotSpot VMs : Lift the hotspot VM and believe that all Java programmers know that it is a virtual machine in the Sun JDK and OPENJDK, and is currently the most widely used Java virtual machine. But not everyone knows that this seemingly "pedigree" virtual machine was not originally developed by Sun, but was designed by a small company called "Longview Technologies" .

Sun mobile-embedded vm/meta-circular VMs: Sun's virtual machines are developed to include not only the server and desktop business virtual machines described previously, but also the mobile and embedded markets that sun faces, Also released virtual machine products, in addition to a class of virtual machines, at the beginning of the design did not have commercial purposes, only for research, verification of a certain technology and ideas, or as a standard implementation

bea JROCKIT/IBM J9 vm: JRockit VM was once known as "The fastest Java virtual machine in the world" (advertising word, seemingly J9 VM also said), it is BEA Company in 2002 from appeal virtual Machines Company acquired the virtual machine. IBM J9 VMS are not IBM's only Java virtual machines, but are currently the main development of Java virtual machines. IBM J9 VM was originally an internal development code, the official name is "IBM technology for Java Virtual Machine", referred to as it4j, but the name is too mouthful a bit, the popularity of less than J9

Azul vm/bea Liquid VM: The Azul VM is a large number of Azul systems improvements on the hotspot basis, running on Azul Systems ' proprietary hardware Vega system Java Virtual machine, Liquid VM is now JRockit VE (virtual Edition), a virtualized version of the JRockit VM developed by BEA that can run directly on its own hypervisor system, Liquid VMS do not require the support of the operating system, or it itself implements the necessary functions of a dedicated operating system, such as file systems, Network support and more.

Apache harmony/google Android Dalvik vm: This section describes the Harmony VMs and Dalvik VMs that can only be called "virtual machines", not "Java Virtual machines", But the two virtual machines (and the technology they represent) have had a huge impact and challenge to the Java world in recent years, and even some pessimistic commentators have suggested that the mature Java ecosystem has the potential to crash.

Microsoft JVM: Perhaps Java programmers may be surprised to hear that Microsoft was once a staunch supporter of Java technology (and must admit that with Sun's control over Java), The technology that makes Java from cross-platform technology to Windows-bound is the main purpose of Microsoft Corporation.

Wait a lot.

1. Into Java (this reading is based on jdk1.7)