Android聊天界面刷新消息

private class RefreshThread implements Runnable{
        private int await = 0;
        private boolean flag = true;
        @Override
        public void run() {
            while (flag) {
                try {
                    Message message =new Message();
                    message.what = 1;
                    handler.sendMessage(message);
                    Thread.sleep(await());
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }   
        }
        public void setFlag(boolean flag) {
            this.flag = flag;
        }
        public long await(){
            if(await > 13){
                return 60000L;
            }
            if (await > 6) {
                return 20000L;
            }
            return await < 3 ? 10000L:15000L;
        }
       public void setAwait(int await) {
            this.await = await;
        }
        public void ascAwait(){           
            await ++;
        }
     }

case i_getMessageInfo:
            ChatMsg chatMsg=ChatMsgData.getChatMsg();
            if(ViewUtil.isNotEmpty(chatMsg)){
                if (Integer.parseInt(chatMsg.getState().toString())>0)
                {
                    synchronized(this) {
                        List<ChatMsgList> chatMsgList=chatMsg.getChatmsglist();
                        size=chatMsgLists.size();
                        chatMsgLists.clear();
                        chatMsgLists.addAll(chatMsgList);
                        myAdapter.notifyDataSetChanged();
                        listView.setSelection(chatMsgLists.size());
                        if (chatMsgLists.size() == size) {
                                    refreshThread.ascAwait();
                              }else {
                                    refreshThread.setAwait(0);
                              }
                    }       
                }
                else
                {
                    showToast("获取消息列表未成功", false);
                }
            }
            break;

private Handler handler = new Handler(){
        @Override
        public void handleMessage(android.os.Message msg) {
            switch (msg.what) {
            case 1:
                sendToBackgroud(OperateCode.i_getMessageInfo,new String[]{PersonalID,""});
                break;
            default:
                break;
            }
            super.handleMessage(msg);
        };
    };