RMI客户端 classnotFound有关问题

import java.rmi.RemoteException;import java.rmi.registry.LocateRegistry;import java.rmi.registry.Registry;import java.rmi.server.UnicastRemoteObject;import News_apart_DAOImp.NAprt_affair_noticeDAOImp;import News_apart_DAOImp.News_apart_DAOImp;import News_aprt_DAO.News_register_factoryDAO;public class News_register_factory extends UnicastRemoteObject implements        News_register_factoryDAO,Runnable {    private String item;    protected News_register_factory() throws RemoteException {        super();        // TODO Auto-generated constructor stub    }    public   boolean register()  throws RemoteException {        if(this.item == "newsDAOImp"){            LocateRegistry.createRegistry(8808);            News_apart_DAOImp news = new News_apart_DAOImp();            try {                Naming.rebind("//localhost:8808/news" , news);                System.out.println("\n news registered");                //registry.unbind("news");              /*  UnicastRemoteObject.unexportObject(registry, true);                System.out.println(">>>>>INFO:服务停止！");                System.exit(0);  //终止RMI服务程序的运行                */            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }                         return true;        }        if(this.item == "NApart_affairImp"){            LocateRegistry.createRegistry(8809);            NAprt_affair_noticeDAOImp affair = new NAprt_affair_noticeDAOImp();            try {                Naming.rebind("//localhost:8809/Naffair" , affair);                System.out.println("\n affair registered");            /*    //registry.unbind("Naffair");                UnicastRemoteObject.unexportObject(registry, true);                System.out.println(">>>>>INFO:服务停止！");                //System.exit(0);  //终止RMI服务程序的运行                 *                  */            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }             return true;        }            if(this.item == "BApart_affairImp"){            LocateRegistry.createRegistry(8810);            NAprt_affair_noticeDAOImp affair = new NAprt_affair_noticeDAOImp();            try {                Naming.rebind("//localhost:8810/Baffair" , affair);            } catch (MalformedURLException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }             return true;        }            return false;    }    public synchronized void  setItem(String it) throws RemoteException {        // TODO Auto-generated method stub        try {            Thread.sleep(10);        } catch (InterruptedException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        this.item = it;    }    public void run() {        // TODO Auto-generated method stub        try {             System.out.println(Thread.currentThread().getName() + " is saling ticket " + register());        } catch (RemoteException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }            }}

package LookUpImp;import java.net.MalformedURLException;import java.rmi.Naming;import java.rmi.NotBoundException;import java.rmi.RemoteException;import NewsDAO.News_register_factoryDAO;public class NLookUp {    public boolean lookup(String item) {        String url = "//localhost:8807/factory";        try {            News_register_factoryDAO factory = (News_register_factoryDAO) Naming                    .lookup("demo");            if (item == "news") {                factory.setItem("news");                new Thread((Runnable) factory).start();                return true;            }        } catch (MalformedURLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (RemoteException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (NotBoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return false;    }}