Dynamic class change/load
Hi,
I have an application that reads different text files which has different Java codes and create Objects with a method that is dynamicly created from the contents of these text files.
I have the following architecture of classes:
public abstract FileScript {
public abstract void run();
}
public Script extends abstract{
public void run(){
System.out.println("Script finished!");
}
}
public ScriptFactory{
...
public ScriptFactory getInstance(){
...
}
private String loadMethodBodyFromFile(String fileName){
....
return methodBody = //loads from filename
}
public Script create(String fileName){
ScriptVO ret = new ScriptVO();
try{
String runMethodStr = loadMethodBodyFromFile(scriptFileName);
ClassPool pool = ClassPool.getDefault();
CtClass clazz = pool.get("Script");
CtMethod method = clazz.getDeclaredMethod("run");
method.insertBefore(runMethodStr);
Class cl = clazz.toClass();
ret = (ScriptVO)clazz.toClass(ClassLoader.getSystemClassLoader()).newInstance();
}catch(Exception exp){
exp.printStackTrace();
throw new ScriptException(exp);
}
return ret;
}
}
public Test{
public static void main(String args[]){
ScriptFactory.getInstance().create("file.txt");
}
}
However I am getting the following error:
javassist.CannotCompileException: by java.lang.LinkageError: duplicate class definition: Script
at javassist.ClassPool.toClass(ClassPool.java:813)
at javassist.ClassPool.toClass(ClassPool.java:765)
at javassist.CtClass.toClass(CtClass.java:985)
at ScriptFactory.create(ScriptFactory.java:37)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
at java.lang.Thread.run(Thread.java:595)
Caused by: java.lang.LinkageError: duplicate class definition: br/com/collector/agent/lib/vo/ScriptVO
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.lang.ClassLoader.defineClass(ClassLoader.java:465)
It seems that there is another Script already loaded by my ClassLoader. So, how is it possible to have this kind of dynamic codes with javassist? Should I need user the HotSwapper class? How can I use it?
Thank you and regards,