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使用Websocket实现消息推送
WebSocket 上
联系客服功能在项目中很难避免,一般有下面三种实现方式:
- 使用http的get方式轮询
- 接入第三方IM系统
- 自己的IM系统
- 基于socket
- 基于websocket
第一种方式,最low的,实现简单,但是浪费用户流量;第二种方式,接入简单,功能强大,但是可能需要一定的成本(比如付费);第三种方式,需要一定的开发成本(服务器托管费用忽略)。对于第三种情况的 socket,实现IM的文字加音视频聊天,做过的话你可以也会直接懵逼。但是,简单的文字聊天还好,不过你还是需要去定义一些协议来实现这样一个功能。如果我们使用websocket,那事情就变的简单很多。
WebSocket一种在单个 TCP 连接上进行全双工通讯的协议。WebSocket通信协议于2011年被IETF定为标准RFC 6455,并被RFC7936所补充规范,WebSocketAPI被W3C定为标准。
WebSocket 是独立的、创建在 TCP 上的协议,和 HTTP 的唯一关联是使用 HTTP 协议的101状态码进行协议切换,使用的 TCP 端口是80,可以用于绕过大多数防火墙的限制。
WebSocket 使得客户端和服务器之间的数据交换变得更加简单,允许服务端直接向客户端推送数据而不需要客户端进行请求,在 WebSocket API 中,浏览器和服务器只需要完成一次握手,两者之间就直接可以创建持久性的连接,并允许数据进行双向传送。
目前常见的浏览器如 Chrome、IE、Firefox、Safari、Opera 等都支持 WebSocket,同时需要服务端程序支持 WebSocket。
来自维基百科 https://zh.wikipedia.org/wiki/WebSocket
websocket只是一种协议,类似http,因此与语言无关。这里我使用java来做服务端,同时提供android和html的客户端,通过一个简单的demo来介绍websocket的使用,接下来的一篇会对websocket进行分析。
服务端
这里我使用 Java-WebSocket 这个库来实现 websocket server。需要的jar包位于项目的 /Java-WebSocket/dist/java-websocket.jar
位置。效果如下:
代码如下:
public class SocketServer extends WebSocketServer { private static final int PORT = 2333; public static void main(String[] args) { SocketServer server = new SocketServer(PORT); server.start(); try { String ip = InetAddress.getLocalHost().getHostAddress(); int port = server.getPort(); print(String.format("服务已启动: %s:%d", ip, port)); } catch (UnknownHostException e) { e.printStackTrace(); } InputStreamReader in = new InputStreamReader(System.in); BufferedReader reader = new BufferedReader(in); while (true) { try { String msg = reader.readLine(); server.broadcastMessage(msg); } catch (Exception e) { e.printStackTrace(); } } } public SocketServer(int port) { super(new InetSocketAddress(port)); } public SocketServer(InetSocketAddress address) { super(address); } @Override public void onOpen(WebSocket webSocket, ClientHandshake clientHandshake) { String address = webSocket.getRemoteSocketAddress().getAddress().getHostAddress(); String message = String.format("(%s) <加入>", address); broadcastMessage(message); print(message); } @Override public void onClose(WebSocket webSocket, int code, String reason, boolean remote) { String address = webSocket.getRemoteSocketAddress().getAddress().getHostAddress(); String message = String.format("(%s) <离开>", address); broadcastMessage(message); print(message); } @Override public void onMessage(WebSocket webSocket, String msg) { String address = webSocket.getRemoteSocketAddress().getAddress().getHostAddress(); String message = String.format("(%s) %s", address, msg); broadcastMessage(message); print(message); } @Override public void onError(WebSocket webSocket, Exception e) { if (null != webSocket) { if (!webSocket.isClosed()) { webSocket.close(0); } } e.printStackTrace(); } /** * 广播收到消息 * * @param msg */ private void broadcastMessage(String msg) { Collection<WebSocket> connections = connections(); synchronized (connections) { for (WebSocket client : connections) { client.send(msg); } } } private static void print(String msg) { System.out.println(String.format("[%d] %s", System.currentTimeMillis(), msg)); }}
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客户端
Android
这里也是用java-websocket这个库,效果如下:
核心代码:
public class WebSocketActivity extends BaseActivity {private static final int STATUS_CLOSE = 0;private static final int STATUS_CONNECT = 1;private static final int STATUS_MESSAGE = 2;@Bind(R.id.etIP)EditText etIP;@Bind(R.id.etPort)EditText etPort;@Bind(R.id.tvStatus)TextView tvStatus;@Bind(R.id.tvMsg)TextView tvMsg;@Bind(R.id.rgVersion)RadioGroup rgVersion;@Bind(R.id.etMessage)EditText etMessage;@Bind(R.id.svContent)ScrollView svContent;@Bind(R.id.viewMain)View viewMain;@Bind(R.id.btConnect)Button btConnect;@Bind(R.id.btDisconnect)Button btDisconnect;@Bind(R.id.btSend)Button btSend;@OnClick({R.id.btConnect, R.id.btDisconnect, R.id.btSend})public void onClick(View view) { switch (view.getId()) { case R.id.btConnect: connectToServer(); break; case R.id.btDisconnect: if (null != mClient) { mClient.close(); } break; case R.id.btSend: if (null != mClient) { String msg = etMessage.getText().toString(); if (!TextUtils.isEmpty(msg)) { try { mClient.send(msg); } catch (NotYetConnectedException e) { e.printStackTrace(); return; } etMessage.setText(""); } } break; default: break; }}private Client mClient;private Handler mHandle = new Handler() { @Override public void handleMessage(Message msg) { String message = String.format("[%d] %s\n", System.currentTimeMillis(), msg.obj.toString()); tvMsg.append(message); switch (msg.what) { case STATUS_CONNECT: btConnect.setEnabled(false); btDisconnect.setEnabled(true); btSend.setEnabled(true); break; case STATUS_CLOSE: btConnect.setEnabled(true); btDisconnect.setEnabled(false); btSend.setEnabled(false); break; case STATUS_MESSAGE: // TODO: 16/8/24 break; default: break; } svContent.postDelayed(new Runnable() { @Override public void run() { svContent.fullScroll(View.FOCUS_DOWN); } }, 100); }};@Overrideprotected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_web_socket); ButterKnife.bind(this); System.setProperty("java.net.preferIPv6Addresses", "false"); System.setProperty("java.net.preferIPv4Stack", "true");}private void connectToServer() { String ip = etIP.getText().toString(); String port = etPort.getText().toString(); if (TextUtils.isEmpty(ip) || TextUtils.isEmpty(port)) { Snackbar.make(viewMain, "IP and Port 不能为空", Snackbar.LENGTH_LONG).show(); return; } String address = String.format("ws://%s:%s", ip, port); Draft draft = null; switch (rgVersion.getCheckedRadioButtonId()) { case R.id.rbDraft10: draft = new Draft_10(); break; case R.id.rbDraft17: draft = new Draft_17(); break; case R.id.rbDraft75: draft = new Draft_75(); break; case R.id.rbDraft76: draft = new Draft_76(); break; default: draft = new Draft_17(); break; } try { URI uri = new URI(address); mClient = new Client(uri, draft); mClient.connect(); } catch (URISyntaxException e) { e.printStackTrace(); return; } tvStatus.setText(address);}private class Client extends WebSocketClient { public Client(URI serverURI) { super(serverURI); } public Client(URI serverUri, Draft draft) { super(serverUri, draft); } @Override public void onOpen(ServerHandshake handShakeData) { Message msg = new Message(); msg.what = STATUS_CONNECT; msg.obj = String.format("[Welcome:%s]", getURI()); mHandle.sendMessage(msg); } @Override public void onMessage(String message) { Message msg = new Message(); msg.what = STATUS_MESSAGE; msg.obj = message; mHandle.sendMessage(msg); } @Override public void onClose(int code, String reason, boolean remote) { Message msg = new Message(); msg.what = STATUS_CLOSE; msg.obj = String.format("[Bye:%s]", getURI()); mHandle.sendMessage(msg); } @Override public void onError(Exception ex) { ex.printStackTrace(); }}}
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Html
H5使用了这个库,效果如下:
核心代码如下:
<script type="text/javascript"> document.observe("dom:loaded", function () { function log(text) { var value = http://www.mamicode.com/(new Date).getTime(); value += ": "; value += text.escapeHTML(); value += $("log").innerHTML; $("log").innerHTML = value; } if (!window.WebSocket) { alert("浏览器不支持,换一个吧"); } var ws; $("connectForm").observe("submit", function (e) { e.stop(); ws = new WebSocket($F("uri")); ws.onopen = function () { log("连接到服务器\n"); } ws.onmessage = function (e) { log("服务器信息: " + e.data + "\n"); } ws.onclose = function () { log("断开服务器连接\n"); $("uri", "connect").invoke("enable"); $("close").disable(); ws = null; } $("uri", "connect").invoke("disable"); $("close").enable(); }); $("close").observe("click", function (e) { e.stop(); if (ws) { ws.close(); ws = null; } }); $("sendForm").observe("submit", function (e) { e.stop(); if (ws) { var message = $("message"); ws.send(message.value); message.value = http://www.mamicode.com/""; message.focus(); } }); });</script>
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所有的代码都可以到github查看。下一篇将通过对websocket协议的分析,来对其做进一步的了解。
使用Websocket实现消息推送