Resource:

The thread to discuss how to add (only) jar files into JVM just like it is added in classpath during start up.

http://forum.java.sun.com/thread.jspa?threadID=300557&start=0&tstart=0

This link talks about how to dynamically plug in/out jar files (the best way)

http://java.sun.com/products/jndi/tutorial/beyond/misc/index.html

A more detailed white paper is available at

http://www.javageeks.com/Papers/ClassForName/index.html

Quoted abstract:

Abstract:

Dynamic loading of Java classes at runtime provides tremendous flexibility in the development of enterprise systems. It provides for the basis of "application servers", and allows even simpler, lighter-weight systems to accomplish some of the same ends. Within Java, dynamic loading is typically achieved by calling the forName method on the class java.lang.Class; however, when Class.forName is naively called from within an Extension, strange errors can occur. This paper describes why those errors occur, and how Java2 provides two facilities, one a modification to the forName syntax, and the other, called the "Thread context ClassLoader", to avoid them. This paper assumes you are passingly familiar with Java Reflection, and have at least a general idea of what Java ClassLoaders are and how they are used within Java code.

Keywords:Java ClassLoaders Extensions Threads

Following is the core code for invokeMethod

    public ReturnValue invokeMethod(

            String moduleName, String className, String methodName, Object[] methodParams)

    {

        //!!!!!check moduleName/className/methodName, undone

        ClassLoader prevCl = Thread.currentThread().getContextClassLoader();

        ReturnValue retVal = new ReturnValue();

        retVal.success = false;

        try {

            File cwd = new File (workDir);

            System.out.println("current work dir: "+cwd.getCanonicalPath());

            String fileSeparator = System.getProperty("file.separator");

            String xsharpCodePackageLocation = cwd.getCanonicalPath()+fileSeparator+moduleName+".jar";

            File xsharpJar = new File(xsharpCodePackageLocation);

            File implJar = new File(implAssemblyLocation);

            // add .jar to class loader

            URL[] urls = new URL[1];

            urls[0]=xsharpJar.toURL();

            ClassLoader urlCl = URLClassLoader.newInstance(urls,prevCl);

            Thread.currentThread().setContextClassLoader(urlCl);            

            Class thisClass = Class.forName(moduleName+"."+className,true,urlCl);

            Object iClass = thisClass.newInstance();

            Method m[] = thisClass.getDeclaredMethods();

            for (int i=0; i<m.length;i++)

            {

                if (methodName.equals(m[i].getName()))

                {

                    m[i].setAccessible(true);

                    retVal.result =  m[i].invoke(iClass, methodParams);

                    retVal.success = true;

                }

            }

        }

        catch (Exception e) {

            retVal.info = e.toString();

        }finally

        {

            Thread.currentThread().setContextClassLoader(prevCl);     

        }

        return retVal;

    }