关于JVM说明的摘要

 

    If the JVM is launched with the JPDA (Java Platform Debugger Architecture) enabled, a class is dynamically reloadable. After the JVM loads a class, the old version of the class definition can be unloaded and a new one can be reloaded again. That is, the definition of that class can be dynamically modified during runtime. However, the new class definition must be somewhat compatible to the old one. The JVM does not allow schema changes between the two versions. They have the same set of methods and fields.

 

     来自:http://www.csg.is.titech.ac.jp/~chiba/javassist/tutorial/tutorial.html