springloaded官方说明：
Spring Loaded is a JVM agent for reloading class file changes whilst a JVM is running. It transforms classes at loadtime to make them amenable to later reloading. Unlike 'hot code replace' which only allows simple changes once a JVM is running (e.g. changes to method bodies), Spring Loaded allows you to add/modify/delete methods/fields/constructors. The annotations on types/methods/fields/constructors can also be modified and it is possible to add/remove/change values in enum types.
Spring Loaded is usable on any bytecode that may run on a JVM, and is actually the reloading system used in Grails 2.
1.下载springloaded-1.2.5.RELEASE.jar，地址：https://github.com/spring-projects/spring-loaded
2. 把springloaded-1.2.5.RELEASE.jar放到tomcat的bin文件夹下
3. 打开bin下的catalina.bat,添加如下一句
set JAVA_OPTS=-javaagent:springloaded-1.2.5.RELEASE.jar -noverify