Reflection Problem - I feel like a Vampire... No reflection found...

[graham king]

Hoping that someone may be able to help me make sense out of this. I'm doing some basic reflective calls that keep failing on the method.invoke().

Servlet call:

protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, java.io.IOException {
        
        String valueToFind = request.getParameter("value");
        String methodToCall = request.getParameter("methodCall");
        String formName = request.getParameter("formName");    
        
        logger.info("value:"+valueToFind+" methodCall"+methodToCall+" formName"+formName);
        
        AutoCompleteDel acd = new AutoCompleteDel();
        
        Class[] methodParmClasses = {String.class};
        Object[] methodParmValues = {valueToFind};
        
        StringBuffer sb = (StringBuffer)
        MirrorMakerImpl.invokeClassMethodOnObject(
        acd,
        "com.comira.del.AutoCompleteDel",
        methodToCall,
        methodParmClasses,
        methodParmValues);
        
        if(acd.areNamesAdded()){
        // return data
        }            
    }

which calls:

public static Object invokeClassMethodOnObject(Object objectToInvoke, String className, String methodName, Class[] methodParmClasses, Object[] methodParmValues){    
Class aClass = getClass(className);

Method aMethod = getMethod(aClass, methodName, methodParmClasses);
return invokeMethod(objectToInvoke, aMethod, methodParmValues);    
    }
 
public static Object invokeMethod(Object obj, Method method, Object[] params){
        try{
            return MirrorMaker.invokeMethod(obj, method, params);
        }catch(IllegalAccessException ex){
            logger.error(ex.getMessage());
        }catch(InvocationTargetException ex){
            logger.error(ex.getMessage());
        }        
        return null;
    }            

which fails on the invoke:

public static Object invokeMethod(Object obj, Method method, Object[] params)throws IllegalAccessException, InvocationTargetException{
        Object ret = null;
        String str = "";
        logger.info("obj name:"+obj.getClass().getName());
        logger.info("method:"+method.getName());
        logger.info("method class:"+method.getDeclaringClass().getName());
        for(int i=0; i<method.getParameterTypes().length; i++) {
        logger.info("method param class:"+method.getParameterTypes()[i].getName());        
        }
        
        //logger.info("params:"+params.toString());
        if(null != params){
        for(int i=0; i<params.length;i++){
        logger.info("params["+i+"]:"+params[i]);
        logger.info("param class:"+params[i].getClass().getName());
        }
        }
        try{
            ret = method.invoke(obj, params);
            if(ret instanceof String){
                str = (String)ret;
                //logger.info("ret str: "+str);                        
            }else if(ret instanceof Integer){
                str = ((Integer)ret).toString();
                //logger.info("ret int: "+str);
            }else if(ret instanceof java.util.Date){
                str = new SimpleDateFormat("yyyy-MM-dd").format(ret);
                logger.info("ret date: "+str);
            }else if(ret instanceof ArrayList){
                return ret;
            }else if(ret instanceof StringBuffer){
            return ret;
            }else
                str = "";
        }catch(IllegalAccessException ex){
            logger.info("illegal access");
            throw ex;
        }catch(InvocationTargetException ex){
            logger.error("invocation target ex:"+ex.getMessage());
            throw ex;
        }           
        return str;
    }

here's the error message:

 [MirrorMaker:53] obj name:com.comira.del.AutoCompleteDel
2007-03-19 13:11:12,656 INFO  [MirrorMaker:54] method:getAutoCompleteBirthPlaces
2007-03-19 13:11:12,656 INFO  [MirrorMaker:55] method class:com.comira.del.AutoCompleteDel
2007-03-19 13:11:12,656 INFO  [MirrorMaker:57] method param class:java.lang.String
2007-03-19 13:11:12,656 INFO  [MirrorMaker:63] params[0]:Berlin
2007-03-19 13:11:12,656 INFO  [MirrorMaker:64] param class:java.lang.String
2007-03-19 13:11:12,656 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/registration].[autoComplete]:260] Servlet.service() for servlet autoComplete threw exception
java.lang.IllegalArgumentException: object is not an instance of declaring class
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.comira.util.MirrorMaker.invokeMethod(MirrorMaker.java:68)
at com.comira.util.MirrorMakerImpl.invokeMethod(MirrorMakerImpl.java:47)
at com.comira.util.MirrorMakerImpl.invokeClassMethodOnObject(MirrorMakerImpl.java:60)
at com.comira.taglib.AutoCompleteServlet.doGet(AutoCompleteServlet.java:40)

It had worked before... I'm not quite sure what I've done wrong.

TIA
[ March 19, 2007: Message edited by: graham king ]

[Herman Schelti]

hi Graham,

can you post (some of) the code of the method(s) from AutoCompleteDel that you want to call?

Herman

[Ernest Friedman-Hill]

Servlet containers are tricky places: there is more than one ClassLoader in use, and seemingly weird things happen if the same class gets loaded by two different ClassLoaders. It's possible that this is what's happened here.

You might try logging the result of "method.getDeclaringClass().getClassLoader() == obj.getClass().getClassLoader()". You'd like this to be true. If it's false, then that explains your problem.

[graham king]

Thanks, Earnest. Thought I was loosing my head. I rewrote the servlet call to work directly with the MirrorMaker class and found that I did indeed have a class loading issue, mainly a lingering .jar file in my WEB-INF/lib dir. I haven't put it back to how it was yet, I'll try it later, but, by removing it from the lib things are doing ok.

Thanks again.