小弟要对一个远程的方法尽心调用.服务端的代码如下,但是发现Hashtable无法返回，请问我该怎么做?
public class ServiceManagerImpl extends GridServiceImpl implements erviceManagerPortType
  {

   .......

public Object list() throws java.rmi.RemoteException
        {
         list_sql_str=new String("select * from services;");    
         try{
             st=con.createStatement();
             rs=st.executeQuery(list_sql_str); 
             System.out.println("list services");
             while(rs.next())
              {
              this.hash_gsh=new String(rs.getString(1)); 
              System.out.println(""+hash_gsh);
              this.WSDL=new String(rs.getString(3));
              System.out.println("    "+WSDL);
              this.hash_jsp=new String(rs.getString(5)); 
              System.out.println("   "+hash_jsp);  
              this.hash_sla=new String(rs.getString(4));
              System.out.println("   "+hash_sla); 
              
              if (!service_list.containsKey(hash_gsh))
                 service_list.put(hash_gsh,new service_hash_content(WSDL,hash_jsp,hash_sla,hash_name)); 
              }
             } catch (SQLException E)
              { 
                System.out.println("SQLException: " + E.getMessage());
                System.out.println("SQLState:    " + E.getSQLState());
                System.out.println("VendorError:  " + E.getErrorCode());
              }
           return service_list;   
      }
    ......