Android Webrtc之Kurento-group-call 简介Kurento-group-call是一个类似视频会议的官方例子，在每个用户端都会创建N个端点，相比one2one-call/one2many-call要复杂些。在用户之间连接多个客户端，创建一个视频会议；同样，运行之前要安装Kurento媒体服务。先克隆项目，然后运行主类：git clone https://github.com/Kurento/kurento-tutorial-java.git cd kurento-tutorial-java/kurento-group-call运行项目mvn -U clean spring-boot:run \ -Dspring-boot.run.jvmArguments="-Dkms.url=ws://{KMS_HOST}:8888/kurento"功能分析用户进入房间时，会创建一个新的Media，另外会通知其他用户有新用户连接，然后所有参于者将请求服务器接收新参于者的媒体。新用户依次获取所有已连接的参于者列表，并请求服务器接收房间中所有客户端的media。每个客户端都发送自己的media，然后从其他用户那里接收媒体，每个客户端都会有n个端点，房间总共会有n*n个端点。当用户离开房间时，服务器会通知所有客户端。然后，客户端代码请求服务器取消与离开的客户端相关的所有媒体元素。服务端实例化Kurento客户端后，您就可以与Kurento媒体服务器通信并控制其多媒体功能了。GroupCallApp实现了接口WebSocketConfigurer，注册了一个WebSocketHandler用于处理WebSocket请求@EnableWebSocket @SpringBootApplication public class GroupCallApp implements WebSocketConfigurer { @Bean public UserRegistry registry() { return new UserRegistry(); } @Bean public RoomManager roomManager() { return new RoomManager(); } @Bean public CallHandler groupCallHandler() { return new CallHandler(); } @Bean public KurentoClient kurentoClient() { return KurentoClient.create(); } public static void main(String[] args) throws Exception { SpringApplication.run(GroupCallApp.class, args); } @Override public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) { registry.addHandler(groupCallHandler(), "/groupcall"); } } CallHandler类实现TextWebSocketHandler处理文本WebSocket请求。这个类的核心部分是方法handleTextMessage。此方法实现请求的操作，通过WebSocket返回响应public class CallHandler extends TextWebSocketHandler { private static final Logger log = LoggerFactory.getLogger(CallHandler.class); private static final Gson gson = new GsonBuilder().create(); @Autowired private RoomManager roomManager; @Autowired private UserRegistry registry; @Override public void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception { final JsonObject jsonMessage = gson.fromJson(message.getPayload(), JsonObject.class); final UserSession user = registry.getBySession(session); if (user != null) { log.debug("Incoming message from user '{}': {}", user.getName(), jsonMessage); } else { log.debug("Incoming message from new user: {}", jsonMessage); } switch (jsonMessage.get("id").getAsString()) { case "joinRoom": joinRoom(jsonMessage, session); break; case "receiveVideoFrom": final String senderName = jsonMessage.get("sender").getAsString(); final UserSession sender = registry.getByName(senderName); final String sdpOffer = jsonMessage.get("sdpOffer").getAsString(); user.receiveVideoFrom(sender, sdpOffer); break; case "leaveRoom": leaveRoom(user); break; case "onIceCandidate": JsonObject candidate = jsonMessage.get("candidate").getAsJsonObject(); if (user != null) { IceCandidate cand = new IceCandidate(candidate.get("candidate").getAsString(), candidate.get("sdpMid").getAsString(), candidate.get("sdpMLineIndex").getAsInt()); user.addCandidate(cand, jsonMessage.get("name").getAsString()); } break; default: break; } } @Override public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception { ... } private void joinRoom(JsonObject params, WebSocketSession session) throws IOException { ... } private void leaveRoom(UserSession user) throws IOException { ... } }在afterConnectionClosed方法里，它会将用户userSession从registry房间中移除并驱逐出去@Override public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception { UserSession user = registry.removeBySession(session); roomManager.getRoom(user.getRoomName()).leave(user); }在joinRoom方法中，服务器检查是否有指定名称的已注册房间，将用户添加到该房间并注册用户private void joinRoom(JsonObject params, WebSocketSession session) throws IOException { final String roomName = params.get("room").getAsString(); final String name = params.get("name").getAsString(); log.info("PARTICIPANT {}: trying to join room {}", name, roomName); Room room = roomManager.getRoom(roomName); final UserSession user = room.join(name, session); registry.register(user); }leaveRoom方法结束一个用户的视频通话private void leaveRoom(UserSession user) throws IOException { final Room room = roomManager.getRoom(user.getRoomName()); room.leave(user); if (room.getParticipants().isEmpty()) { roomManager.removeRoom(room); } }客户端创建WebSocket，在onMessage方法下监听JSON信令协议。有5个不用的消息传入到客户端：existingParticipants,newParticipantArrived,participantLeft,receiveVideoAnswer和iceCandidate。var ws = new WebSocket('wss://' + location.host + '/groupcall'); var participants = {}; var name; window.onbeforeunload = function() { ws.close(); }; ws.onmessage = function(message) { var parsedMessage = JSON.parse(message.data); console.info('Received message: ' + message.data); switch (parsedMessage.id) { case 'existingParticipants': onExistingParticipants(parsedMessage); break; case 'newParticipantArrived': onNewParticipant(parsedMessage); break; case 'participantLeft': onParticipantLeft(parsedMessage); break; case 'receiveVideoAnswer': receiveVideoResponse(parsedMessage); break; case 'iceCandidate': participants[parsedMessage.name].rtcPeer.addIceCandidate(parsedMessage.candidate, function (error) { if (error) { console.error("Error adding candidate: " + error); return; } }); break; default: console.error('Unrecognized message', parsedMessage); } } function register() { name = document.getElementById('name').value; var room = document.getElementById('roomName').value; document.getElementById('room-header').innerText = 'ROOM ' + room; document.getElementById('join').style.display = 'none'; document.getElementById('room').style.display = 'block'; var message = { id : 'joinRoom', name : name, room : room, } sendMessage(message); } function onNewParticipant(request) { receiveVideo(request.name); } function receiveVideoResponse(result) { participants[result.name].rtcPeer.processAnswer (result.sdpAnswer, function (error) { if (error) return console.error (error); }); } function callResponse(message) { if (message.response != 'accepted') { console.info('Call not accepted by peer. Closing call'); stop(); } else { webRtcPeer.processAnswer(message.sdpAnswer, function (error) { if (error) return console.error (error); }); } } function onExistingParticipants(msg) { var constraints = { audio : true, video : { mandatory : { maxWidth : 320, maxFrameRate : 15, minFrameRate : 15 } } }; console.log(name + " registered in room " + room); var participant = new Participant(name); participants[name] = participant; var video = participant.getVideoElement(); var options = { localVideo: video, mediaConstraints: constraints, onicecandidate: participant.onIceCandidate.bind(participant) } participant.rtcPeer = new kurentoUtils.WebRtcPeer.WebRtcPeerSendonly(options, function (error) { if(error) { return console.error(error); } this.generateOffer (participant.offerToReceiveVideo.bind(participant)); }); msg.data.forEach(receiveVideo); } function leaveRoom() { sendMessage({ id : 'leaveRoom' }); for ( var key in participants) { participants[key].dispose(); } document.getElementById('join').style.display = 'block'; document.getElementById('room').style.display = 'none'; ws.close(); } function receiveVideo(sender) { var participant = new Participant(sender); participants[sender] = participant; var video = participant.getVideoElement(); var options = { remoteVideo: video, onicecandidate: participant.onIceCandidate.bind(participant) } participant.rtcPeer = new kurentoUtils.WebRtcPeer.WebRtcPeerRecvonly(options, function (error) { if(error) { return console.error(error); } this.generateOffer (participant.offerToReceiveVideo.bind(participant)); });; } function onParticipantLeft(request) { console.log('Participant ' + request.name + ' left'); var participant = participants[request.name]; participant.dispose(); delete participants[request.name]; } function sendMessage(message) { var jsonMessage = JSON.stringify(message); console.log('Sending message: ' + jsonMessage); ws.send(jsonMessage); } 这里主要依赖于kurento-utils来完成Android上面是官方的代码分析，接下来主要用Android来实现客户端功能，跟one2one一样，都是引用org.webrtc： implementation 'org.webrtc:google-webrtc:1.0.32006' implementation 'org.java-websocket:Java-WebSocket:1.5.3' implementation "com.google.code.gson:gson:2.+"初始化WebSocket,在onMessage里监听JSON信令消息，实现五个方法：existingParticipants,newParticipantArrived,participantLeft,receiveVideoAnswer和iceCandidate when (id) { "existingParticipants" -> { onExistingParticipants(jsonObject) } "newParticipantArrived" -> { onNewParticipantArrived(jsonObject) } "participantLeft" -> { onParticipantLeft(jsonObject) } "receiveVideoAnswer" -> { onReceiveVideoAnswer(jsonObject) } "iceCandidate" -> { iceCandidate(jsonObject) } }existingParticipants：在加入房间后会收到existingParticipants，并告诉有哪些参于者newParticipantArrived：如果有新的参于者加入时，会收到此信息participantLeft：有参于者离开，会收到此信息receiveVideoAnswer：接收到服务器发送的Answer信令iceCandidate：candidates事件发送给服务端的请求：joinRoom：加入到房间的请求receiveVideoFrom：发起接收某参于者时间的请求leaveRoom：离开房间的请求onIceCandidate：将candidate发送到服务端手机与电脑完成连接