code: @Test public void TestCallbackMultiInstans() throws Exception {
    initOrResetUrl(2,1000);
    initOrResetService();
    IDemoCallback callback=new IDemoCallback(){
      public String yyy(    String msg){
        System.out.println("callback1:" + msg);
        return "callback1 onChanged ," + msg;
      }
    }
  ;
    IDemoCallback callback2=new IDemoCallback(){
      public String yyy(    String msg){
        System.out.println("callback2:" + msg);
        return "callback2 onChanged ," + msg;
      }
    }
  ;
  {
      demoProxy.xxx2(callback);
      Assert.assertEquals(1,demoProxy.getCallbackCount());
      Thread.sleep(500);
      demoProxy.unxxx2(callback);
      Assert.assertEquals(0,demoProxy.getCallbackCount());
      System.out.println("");
      demoProxy.xxx2(callback2);
      Assert.assertEquals(1,demoProxy.getCallbackCount());
      Thread.sleep(500);
      demoProxy.unxxx2(callback2);
      Assert.assertEquals(0,demoProxy.getCallbackCount());
      System.out.println("");
      demoProxy.xxx2(callback);
      Thread.sleep(500);
      Assert.assertEquals(1,demoProxy.getCallbackCount());
      demoProxy.unxxx2(callback);
      Assert.assertEquals(0,demoProxy.getCallbackCount());
    }
  {
      demoProxy.xxx2(callback);
      Assert.assertEquals(1,demoProxy.getCallbackCount());
      demoProxy.xxx2(callback);
      Assert.assertEquals(1,demoProxy.getCallbackCount());
      demoProxy.xxx2(callback2);
      Assert.assertEquals(2,demoProxy.getCallbackCount());
    }
    destroyService();
  }
  