存根类(stub) 是什么意思？有什么作用？(转)

 1 public class BusStub extends AbsEngineHandle implements ITBusStub,IMonitor  
 2 {  
 3     public static interface MsgPriorityStrategy  
 4     {  
 5         public int onRecvResultPriority(Msg.MsgInfo msg);  
 6         public int onRecvFromSessionPriority(ITServerSession s,         Msg.MsgInfo msg);  
 7     }  
 8        
 9     public static class ResultPriorMsgPriorityStrategy implements MsgPriorityStrategy  
10     {  
11         public int onRecvResultPriority(Msg.MsgInfo msg)  
12         {  
13             return DefaultEngine.PRIO_HIGH;  
14         }  
15    
16         public int onRecvFromSessionPriority(ITServerSession s, Msg.MsgInfo msg)  
17         {  
18             return DefaultEngine.PRIO_DEFAULT;  
19         }  
20     }  
21        
22     AtomicInteger m_curSessionIdx = new AtomicInteger(1);  
23    
24     IMsgQueue<Msg.MsgInfo> m_cmdQue = new MsgQueue<Msg.MsgInfo>("cmd");  
25     IMsgQueue<Msg.MsgInfo> m_resultQue = new MsgQueue<Msg.MsgInfo>("result");  
26    
27     ConcurrentHashMap<Integer, ITServerSession> m_svc = new ConcurrentHashMap<Integer, ITServerSession>();  
28    
29     NotifyReg m_reg = new NotifyReg();  
30    
31     ITDispatch m_dispatch;  
32    
33     ITAclInterface m_acl = ITAclInterface.s_defaultAcl;  
34     String m_uuid = UUID.randomUUID().toString();  
35     String m_name;  
36        
37     MsgPriorityStrategy m_msgPriorityStrategy;  
38        
39     LongStatPrp sp_cmdnum = new LongStatPrp("recv cmd",0);  
40     LongStatPrp sp_resultnum = new LongStatPrp("send result",0);  
41     LongStatPrp sp_notifynum = new LongStatPrp("send notify",0);  
42        
43     private static final Log logger = LogFactory.getLog("comm");  
44        
45     public BusStub(String name)  
46     {  
47         this(name, null);  
48     }  
49    
50     public BusStub(String name, MsgPriorityStrategy msgPriorityStrategy)  
51     {  
52         m_name = name;  
53         m_msgPriorityStrategy = msgPriorityStrategy;  
54     }  
55        
56        
57     public String getName()  
58     {  
59         return m_name;  
60     }  
61     public void setName(String name)  
62     {  
63         m_name = name;  
64     }  
65    
66     public String getUUID()  
67     {  
68         return m_uuid;  
69     }