1）problem

出现 java.rmi.UnmarshalException:   error   unmarshalling   return;   nested   exception   is:   

java.lang.ClassNotFoundException 异常的原因是，在命令行执行 rmiregistry，并没有指定好 绑定时查找的类文件的路径。

2）solution

以上图片是我的一个荔枝，我的需要绑定的类所属类名如下：

package com.corejava.chapter11.activation.server;import java.rmi.*;/**The remote interface for a simple warehouse.@version 1.0 2007-10-09@author Cay Horstmann
*/
// 远程对象的接口必须扩展Remote接口
public interface Warehouse extends Remote
{  double getPrice(String description) throws RemoteException;
}

我们通过如下语句将该类注册到注册表（ Naming.rebind("rmi://localhost:1099/central_warehouse", centralWarehouse);
）时，1099是 rmiregistry的启动默认端口，发送该绑定请求后，registry 就会去查找要绑定的 centralWarehouse 所属的类名，也即是 com.corejava.chapter11.activation.server.Warehouse。

package com.corejava.chapter11.activation.server;import java.io.*;
import java.rmi.*;
import java.rmi.activation.*;
import java.util.*;import javax.naming.*;public class WarehouseActivator
{public static void main(String[] args) throws RemoteException,NamingException, ActivationException, IOException,AlreadyBoundException{System.out.println("Constructing activation descriptors...");System.setProperty("java.security.policy","com/corejava/chapter11/activation/server/server.policy");System.setSecurityManager(new SecurityManager());// 如何构建激活程序Properties props = new Properties();// use the server.policy file in the current directoryprops.put("java.security.policy", new File("com/corejava/chapter11/activation/server/server.policy").getCanonicalPath());// step1)需要定义一个激活组// step2） 然后如下构造一个激活组描述符：ActivationGroupDesc group = new ActivationGroupDesc(props, null);// step3)创建一个组IDActivationGroupID id = ActivationGroup.getSystem().registerGroup(group);Map<String, Double> prices = new HashMap<>();prices.put("Blackwell Toaster", 24.95);prices.put("ZapXpress Microwave Oven", 49.95);MarshalledObject<Map<String, Double>> param = new MarshalledObject<Map<String, Double>>(prices);String codebase = "http://localhost:8080/";// step4） 构造一个激活描述符了。对于需要构造的每一个对象，都应该包括以下内容（contents）：// 激活组ID + 类的名字 + URL字符串 + 编组后的构造信息// LocateRegistry.createRegistry(1099);ActivationDesc desc = new ActivationDesc(id,"com.corejava.chapter11.activation.server.WarehouseImpl",codebase, param);Warehouse centralWarehouse = (Warehouse) Activatable.register(desc);Naming.rebind("rmi://localhost:1099/central_warehouse", centralWarehouse);System.out.println("Exiting...");}
}