Rmi客户端不使用代码库

时间：2013-12-03 18:47:39

标签： java rmi codebase

我已经编程rmi一段时间了，过了一个月之后我仍然陷入棘手的问题。我想从服务器向客户端发送一个Serialized对象，我希望客户端从服务器代码库下载该对象的类。如果客户端的类路径中没有对象的类，我就无法工作。这就是我一直在做的事情：

我有一个ClientLoader要求ClientPlayer到AuthServer。 ClientLoader还应下载ClientPlayer的类并动态加载。

这是身份验证服务器，应该创建一个对象ClientPlayer（或ClientAdmin）并将其返回给ClientLoader。 （为了简洁起见，我省略了接口;无论如何AlfaBetaInt表示Beta实现它并且Alfa使用它）

public class AuthServer extends UnicastRemoteObject implements LoaderAuthInt{

    private static MasterServer master;

    public AuthServer() throws RemoteException{
        super();
    }

    public Runnable login(String username, String password) throws RemoteException{
    System.out.println("Requested login with username '" + username + "' and password '" + password + "'");
    if(password.equals("admin"))
        return (Runnable)(new ClientAdmin());
    else

        return (Runnable)(new ClientPlayer(username, (PlayerMasterInt)master));
}

    public static void main(String[] args){

        if(System.getSecurityManager() == null)
        System.setSecurityManager(new RMISecurityManager());

        String port = args[0];

        System.out.println("Current codebase:" + System.getProperty("java.rmi.server.codebase"));

        try{
            master = new MasterServer();//create master server
            System.out.println("MasterServer creato.");

            AuthServer auth = new AuthServer();//create auth server
            System.out.println("AuthServer created.");
            Naming.rebind("//:" + port + "/authServer", (LoaderAuthInt)auth);//rebind auth server
            System.out.println("AuthServer rebinded.");
        }catch(Exception e){
            System.err.println(e);
            System.exit(1);
        }
    }
}

这是ClientLoader，它应该从服务器下载ClientPlayer（对象和类）并运行它。

public class ClientLoader{

    public static void main(String[] args){
        if(System.getSecurityManager() == null)
        System.setSecurityManager(new RMISecurityManager());

    Console console = System.console();

    String host = args[0];

    try{
                    //check to see if Server is registered in rmiregistry
        String[] lista = Naming.list("//" + host );
        for( int i = 0; i < lista.length; i = i+1)
            System.out.println(lista[i]);
            //look up the client
        LoaderAuthInt authServer = (LoaderAuthInt)Naming.lookup("//" + host + "/authServer");
        System.out.println("Lookup succesful.");
        if( authServer != null)
            System.out.println("authServer != null.");
        //RUN THE CLIENT!
        Runnable client = authServer.login(console.readLine("Username: "), new String(console.readPassword("Password: ")));

        if(client == null)
            System.err.println("Login not valid");
        else
            client.run();

        System.out.println("Bye bye");
    }catch(Exception e){
        System.err.println(e);
        System.exit(1);
    }
}
}

这是应该从AuthServer发送到ClientLoader的对象：

public class ClientPlayer implements Runnable, Serializable, GamePlayerInt{

private String username;
private PlayerMasterInt master;

public ClientPlayer(String username, PlayerMasterInt master){
    this.username = username;
    this.master = master;
}

public void run(){
    Console console = System.console();

    System.out.println("I'm a succesfully authenticated ClientPlayer!");
}catch(RemoteException e){
            System.err.println(e);
                System.exit(1);
        }
    }
}

public String getUsername() throws RemoteException{
    return username;
}
}

以下是启动服务器的脚本：请注意，我确实指定了代码库，并将属性useCodeBaseOnly设置为false 

if [ "$1" == "" -o "$2" == "" ]; then
    echo "usage: $0 <ip> <port number>"
else
java    -Djava.rmi.server.codebase=http://$1:8000/ \
        -Djava.rmi.server.hostname=$1 \
        -Djava.security.policy=policy \
        -Djava.rmi.server.useCodebaseOnly=false \
        card.AuthServer $2
fi

以下是我发布ClientLoader的方法：再次，我设置了代码库并useCodeBaseOnly 

if [ "$1" == "" -o "$2" == "" ]; then
    echo "usage: $0 <ip> <port>"
else
    java    -Djava.security.policy=policy \
        -Djava.rmi.server.useCodebaseOnly=true \
        -Djava.rmi.server.codebase=http://$1:8000/ \
        card.ClientLoader "$1:$2"
fi

服务器运行良好;我在端口8000有一个http服务器，在端口2378有一个rmiregistry。客户端加载器运行...准精确：rmiregistry上的方法list()显示绑定的服务器，服务器的查找工作，我可以从服务器下载客户端，但是当我运行它时，我得到了ClassNotFoundException：

    java.rmi.UnmarshalException: error unmarshalling return; nested exception is: 
java.lang.ClassNotFoundException: card.ClientPlayer (no security manager: RMI class loader disabled)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:196)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:194)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:148)
at com.sun.proxy.$Proxy0.login(Unknown Source)
at card.ClientLoader.main(ClientLoader.java:26)
Caused by: java.lang.ClassNotFoundException: card.ClientPlayer (no security manager: RMI class loader disabled)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:395)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:185)
at java.rmi.server.RMIClassLoader$2.loadClass(RMIClassLoader.java:637)
at java.rmi.server.RMIClassLoader.loadClass(RMIClassLoader.java:264)
at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:222)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1610)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1515)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1769)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1348)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
at sun.rmi.server.UnicastRef.unmarshalValue(UnicastRef.java:324)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:173)
... 4 more

我怀疑ClientLoader没有使用正确的代码库...非常感谢任何帮助!!

修改：我按照建议将-Djava.security.manager添加到客户端启动脚本中......但这会导致这些安全例外：

Exception in thread "main" java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "writeFileDescriptor")
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:372)
at java.security.AccessController.checkPermission(AccessController.java:559)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
at java.lang.SecurityManager.checkWrite(SecurityManager.java:954)
at java.io.FileOutputStream.<init>(FileOutputStream.java:244)
at java.io.Console.<init>(Console.java:566)
at java.io.Console.<init>(Console.java:92)
at java.io.Console$2.console(Console.java:540)
at java.lang.System.console(System.java:211)
at card.ClientLoader.main(ClientLoader.java:14)

请注意，我确实有政策文件（授予AllPermission）！选项-Djava.security.manager是否会改变策略配置？

修改：政策文件中有拼写错误。 [我被允许讨厌java rmi吗？]所以，回到ClassNotFoundException，虽然风格略有不同：

java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.lang.ClassNotFoundException: card.ClientPlayer
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:196)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:194)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:148)
at com.sun.proxy.$Proxy0.login(Unknown Source)
at card.ClientLoader.main(ClientLoader.java:25)
Caused by: java.lang.ClassNotFoundException: card.ClientPlayer
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.rmi.server.LoaderHandler$Loader.loadClass(LoaderHandler.java:1208)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at sun.rmi.server.LoaderHandler.loadClassForName(LoaderHandler.java:1221)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:454)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:185)
at java.rmi.server.RMIClassLoader$2.loadClass(RMIClassLoader.java:637)
at java.rmi.server.RMIClassLoader.loadClass(RMIClassLoader.java:264)
at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:222)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1610)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1515)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1769)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1348)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
at sun.rmi.server.UnicastRef.unmarshalValue(UnicastRef.java:324)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:173)
... 4 more

有什么想法吗？我真的很难让这个工作......

1 个答案:

答案 0 :(得分：2)

如果您仔细观察堆栈跟踪，您会看到答案已经给出：

  

没有安全管理器：禁用了RMI类加载器

为了通过RMI支持类下载，必须安装SecurityManager。最简单的方法是System.setSecurityManager(new SecurityManager());

但是，当然，您必须编辑策略以允许您的代码执行您想要执行的操作。

→编辑：我看，你似乎已经这样做了，但忘了命令行上的-Djava.security.manager选项。使用此选项与上面的代码段具有相同的效果，它使用策略文件安装默认的SecurityManager。

或者，您可以实施自己的SecurityManager。出于测试目的，只需允许所有内容即可轻松实现SecurityManager，但不建议将其用于生产代码。

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