Android 关于WebSocket的应用

关于WebSocket，个人理解是一种网络协议，好比http,好处在于可以建立一条服务器与客户端长久的连接，从而减少每次通信都需重新建立连接而产生的损耗；缺点在于如果客户端是智能设备，当处于休眠状态时，会自动关闭网络（未测试），还有长链接的流量大小（未测试）。用途多在于即时通信，网上聊天室等。websocket 简介：http://www.html5rocks.com/zh/tutorials/websockets/basics/

服务端是用tomcat7,该版本已支持websocket，很方便。注意7.0.38之前版本会出现长链接自动断开，之后的版本修复了这个问题，我当前的版本是7.0.42.

@WebServlet("/sosWebSocketService") //服务名称 
public class TestWebSocketServlet extends WebSocketServlet{
	private final Map map = new HashMap(); //注册客户端
	
    /** 
     *  
     */  
    private static final long serialVersionUID = -1058445282919079067L;  
  
    @Override  
    protected StreamInbound createWebSocketInbound(String arg0, HttpServletRequest req) { 
        return new ChatMessageInbound(req.getParameter("userCode"));  
    }  
  
    class ChatMessageInbound extends MessageInbound {  
    	private String key = "";
  
    	public ChatMessageInbound(String key) {
    		this.key = key;
    	}
        @Override  
        protected void onOpen(WsOutbound outbound) {  
            map.put(key, outbound);  
            super.onOpen(outbound);  
        }  
  
        @Override  
        protected void onClose(int status) {  
            map.remove(key);  
            super.onClose(status);  
        }  
  
        @Override  
        protected void onBinaryMessage(ByteBuffer buffer) throws IOException {  
            // TODO Auto-generated method stub  
  
        }  
  
        @Override  
        protected void onTextMessage(CharBuffer buffer) throws IOException {  
            String msg = buffer.toString();  //接受客户端消息
            broadcast(msg);  
        }  
  
        private void broadcast(String msg) {  
            Set set = map.keySet();  
            for (String integer : set) {  
                WsOutbound outbound = map.get(integer);  
                CharBuffer buffer = CharBuffer.wrap(msg);  
                try {  
                    outbound.writeTextMessage(buffer);  //向客户端发送消息
                    outbound.flush();  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
    }

}

android端：autobahn 官网： http://autobahn.ws/ 里面有详细说明，还有测试demo下载。我用了service的机制去实现，即时退出应用，服务仍可在后台运行，给出的代码去掉了次要的部分。

public class SosWebSocketClientService extends Service{
	private final String TAG = "SosWebSocketClientService";
	private final WebSocketConnection mConnection = new WebSocketConnection();
	SharedPreferencesUtil spu;
	private final IBinder mBinder = new SosWebSocketClientBinder();
			
	@Override
	public IBinder onBind(Intent intent) {
		return mBinder;
	}
	
	@Override
	public void onCreate() {
		spu = new SharedPreferencesUtil(SosWebSocketClientService.this, SharedPreferencesUtil.STR_XMLFILE);
		mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE); 
		initWebSocket();
		super.onCreate();
		Log.d(TAG, "Service Create");
	}

	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
		return START_STICKY;
	}
	
	/**
	 * 销毁
	 */
	@Override
	public void onDestroy() {
		if (mConnection.isConnected()) {
	         mConnection.disconnect();
	      }
		super.onDestroy();
		Log.d(TAG, "Service Destroy");
	}
	
	private void initWebSocket(){
		//注意连接和服务名称要一致
		/*final String wsuri = "ws://192.168.0.2：8080/st/sosWebSocketService?userCode=" 
				+ spu.getValue(LoginActivity.STR_USERNAME);*/
		Log.d(TAG, Config.getSosWebSocketUrl() + "/userCode=" + spu.getValue(SharedPreferencesUtil.STR_USERCODE));
		final String wsuri = Config.getSosWebSocketUrl() +
					"?userCode=" + spu.getValue(SharedPreferencesUtil.STR_USERCODE);
		 try {
		        mConnection.connect(wsuri, new WebSocketHandler() {
		           @Override
		           public void onOpen() {
		        	  Log.i(TAG, "WebSocket open");
		              
		           }

		           @Override
		           public void onTextMessage(String text) {
		        	   Log.i(TAG, "onTextMessage");
		        	   showNotification(text); 
		           }

		           @Override
		           public void onClose(int code, String reason) {
		        	   Log.i(TAG, "Connection lost.");/*alert("Connection lost.");*/
		              
		           }
		        });
		     } catch (WebSocketException e) {
		        Log.d(TAG, e.toString());
		     }
	}
	
	 
	
	public class SosWebSocketClientBinder extends Binder {
		public SosWebSocketClientService getService() {
			return SosWebSocketClientService.this;
		}
		
		public void sendXxx(String addr){
	        if(mConnection.isConnected())
	        	mConnection.sendTextMessage("xxx");
	         
		}
	}

}