RMI - 在运行时获取ClassNotFoundException

时间：2011-04-26 09:30:45

标签： java rmi

我花了差不多五个小时试图解决这个问题，但无济于事。我创建了一个使用RMI的应用程序。编译很好，但我不能让它运行。 我的所有类文件都在C：\ Users \ Benji \ Desktop \ ass2 \ build中（“赋值”的缩写;没有任何脏）。所有源文件都在C：\ Users \ Benji \ Desktop \ ass2 \ src中。 我已将所有内容放在一个包中以使事情更易于理解（并更改源中的import语句以反映这一点）。

我已将批处理文件放在C：\ Users \ Benji \ Desktop \ ass2 \中。它包含执行语句：

java -classpath ./build -Djava.rmi.server.codebase=file:/C:/Users/Benji/Desktop/ass2/build -Djava.security.policy=broker.policy BrokerReception Broker 16890

（程序需要两个“经纪人”和“16890”）。

文件broker.policy也位于C：\ Users \ Benji \ Desktop \ ass2 \中。其内容如下：

grant
{
    permission java.security.AllPermission;
};

（是的，我意识到这不是一个好的安全政策。我稍后会讨论这个问题。）

实际上有三个Main类，一个用于客户端，一个用于代理（客户端的中介）和服务器。我正在尝试启动经纪人。 Broker接口的代码如下：

import java.io.FileNotFoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.util.ArrayList;

public interface Broker extends Remote
{
    public boolean getAvailability(int startDate, int endDate) throws FileNotFoundException, RemoteException;

    public ArrayList<CityInfo> getCities() throws FileNotFoundException, RemoteException;

    public ArrayList<HotelInfo> getCityHotels(int cityNumber) throws FileNotFoundException, RemoteException;

    public int getHotelRoomRate(int hotelNumber) throws FileNotFoundException, RemoteException;

    public boolean makeBooking(String firstName, String lastName, String contact, String creditCardNo) throws FileNotFoundException, RemoteException;
}

实施类：

import java.io.FileNotFoundException;
import java.util.ArrayList;

public class BrokerClientLiaison implements Broker
{
    private BrokerDatabase directory;
    private BrokerHotelsLiaison liaison;

    public BrokerClientLiaison(BrokerDatabase directory, int activeHotelNumber)
    {
        this.liaison = new BrokerHotelsLiaison(activeHotelNumber);
        this.directory = directory;
    }

    public boolean getAvailability(int startDate, int endDate) throws FileNotFoundException
    {
        return liaison.getAvailability(startDate, endDate);
    }

    public ArrayList<CityInfo> getCities() throws FileNotFoundException
    {
        return directory.getCities();
    }

    public ArrayList<HotelInfo> getCityHotels(int cityNumber) throws FileNotFoundException
    {
        return directory.getCityHotels(cityNumber);
    }

    public int getHotelRoomRate(int hotelNumber) throws FileNotFoundException
    {
        return liaison.getHotelRoomRate(hotelNumber);
    }

    public boolean makeBooking(String firstName, String lastName, String contact, String creditCardNo) throws FileNotFoundException
    {
        return liaison.makeBooking(firstName, lastName, contact, creditCardNo);
    }
}

最后，启动实现类的主类：

import java.io.FileNotFoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;
import java.sql.SQLException;

public class BrokerReception
{
    public static void main(String[] args)
    {
        System.out.println("Args are:");
        for(String arg : args)
        {
            System.out.println(arg);
        }
        System.out.println();

        try
        {
            BrokerDatabase directory = new BrokerDatabase();
            directory.connect(args[0]);

            int activeHotelNumber = Integer.parseInt(args[1]);
            if(directory.checkActiveHotelExists(activeHotelNumber))
            {
                BrokerClientLiaison liaison = new BrokerClientLiaison(directory, activeHotelNumber);
                Broker liaisonStub = (Broker) UnicastRemoteObject.exportObject(liaison, 0);
                Registry registry = LocateRegistry.getRegistry();
                registry.rebind(Protocol.BROKER_INTERFACE_NAME, liaisonStub);
            }
            else
            {
                throw new FileNotFoundException();
            }
        }
        catch(ArrayIndexOutOfBoundsException aioobe)
        {
            System.err.println("Args required:");
            System.err.println("1. Name of database file");
            System.err.println("2. Number of active hotel");
            System.exit(1);
        }
        catch(ClassNotFoundException cnfe)
        {
            System.err.println("Couldn't load database driver");
            System.exit(2);
        }
        catch(SQLException sqle)
        {
            System.err.println("Couldn't establish connection to database");
            System.err.println("Check that the database has been properly registerd,");
            System.err.println("and that you provided the correct name");
            System.exit(3);
        }
        catch(NumberFormatException nfe)
        {
            System.err.println("Second argument must be an integer");
            System.exit(4);
        }
        catch(FileNotFoundException fnfe)
        {
            System.err.println("The database contains no entries with that hotel number");
            System.exit(5);
        }
        catch(RemoteException re)
        {
            System.err.println("Unable to bind as " + Protocol.BROKER_INTERFACE_NAME);
            re.printStackTrace();
            System.exit(6);
        }
    }
}

上述代码中的“目录”是访问数据库的类。

我不知道我需要提供什么其他信息。谁能告诉我我做错了什么？ 顺便说一句，我回去并在http://download.oracle.com/javase/1.5.0/docs/guide/rmi/hello/hello-world.html做了Oracle的RMI教程，看看我是否能弄明白什么是错的。本教程未提及代码库或安全策略，但提供了编译和执行的所有代码和精确指令。我按照这些说明写了这封信，但即使这样也行不通！

堆栈追踪：

java.rmi.ServerException: RemoteException occurred in server thread; nested exce
ption is:
        java.rmi.UnmarshalException: error unmarshalling arguments; nested excep
tion is:
        java.lang.ClassNotFoundException: Broker
        at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:396
)
        at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:250)
        at sun.rmi.transport.Transport$1.run(Transport.java:159)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
        at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:5
35)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTranspor
t.java:790)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport
.java:649)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExec
utor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
.java:908)
        at java.lang.Thread.run(Thread.java:662)
        at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Stream
RemoteCall.java:255)
        at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:
233)
        at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:359)
        at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
        at BrokerReception.main(BrokerReception.java:32)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested ex
ception is:
        java.lang.ClassNotFoundException: Broker
        at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source)
        at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:386
)
        at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:250)
        at sun.rmi.transport.Transport$1.run(Transport.java:159)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
        at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:5
35)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTranspor
t.java:790)
        at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport
.java:649)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExec
utor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
.java:908)
        at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassNotFoundException: Broker
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:247)
        at sun.rmi.server.LoaderHandler.loadProxyInterfaces(LoaderHandler.java:7
11)
        at sun.rmi.server.LoaderHandler.loadProxyClass(LoaderHandler.java:655)
        at sun.rmi.server.LoaderHandler.loadProxyClass(LoaderHandler.java:592)
        at java.rmi.server.RMIClassLoader$2.loadProxyClass(RMIClassLoader.java:6
28)
        at java.rmi.server.RMIClassLoader.loadProxyClass(RMIClassLoader.java:294
)
        at sun.rmi.server.MarshalInputStream.resolveProxyClass(MarshalInputStrea
m.java:238)
        at java.io.ObjectInputStream.readProxyDesc(ObjectInputStream.java:1530)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1492)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1
731)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
        ... 12 more

1 个答案:

答案 0 :(得分：1)

如果您将注册表作为第二个进程运行，则需要访问您的远程类。最简单的方法是在启动注册表时向命令行添加适当的类路径参数。

如果您尝试使用远程类加载，我相信您需要在命令行或主方法中在应用程序中设置rmi安全管理器。 （就个人而言，分发课程通常适用于99％的情况，并且容易100倍正确）。

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