1 背景
webrtc的代码中有peerconnectionclient和peerconnectionserver的例子，但是没有对应的web端的例子，这里简单的写了一个测试例子，具体如下：
2 具体操作
2.1 操作流程
2.2 测试效果
使用webclient与peerconnectionclient的测试效果如下：
3 前端代码
<html>
<head><title>webclient p2p demo</title><meta charset="utf-8"><style>.left_part {width: 50%;float: left;}.right_part {width: 50%;float: right;overflow-y: scroll;}</style><script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</head><body><div class="right_part" id="left_part_container"><div>SignalServer:<input type="text" id="signal_url" value="127.0.0.1:8888"><button id="btn_sign_in">登入</button><button id="btn_sign_out">登出</button><br><input type="text" id="selected_peerid_for_p2p" disabled value="不允许修改的文本"><button id="btn_start_p2p" disabled>start_p2p</button></div><br><table id="PeersTable"><thead><tr><th>Name</th><th>PeerId</th><th>Status</th></tr></thead></table></div><div class="left_part" id="left_part_container"><video controls autoplay id="rtc_video_play" height="500" style="width:100%"></video></div><script type="text/javascript">var myselfPeerId = -1;var pc = new RTCPeerConnection({ "offerExtmapAllowMixed": false });var datachannel = null;var stream = new MediaStream();async function initPC() {pc.addTransceiver("audio", {direction: "recvonly"});pc.addTransceiver("video", {direction: "recvonly"});pc.onconnectionstatechange = function(event){console.log("connection state change: ", pc.connectionState);};pc.onicecandidate = async (ev) => {console.log('=======>' + JSON.stringify(ev.candidate)); };pc.ontrack = function(event) {stream.addTrack(event.track); };datachannel = pc.createDataChannel('chat');datachannel.onopen = function(event) {console.log("datachannel onopen: ", event.data);}datachannel.onmessage = function(event) {console.log("receive message: ", event.data);}datachannel.onerror = function(event) {console.log("datachannel error: ", event.data);}datachannel.onclose = function(event) {console.log("datachannel close: ");} }async function startP2P(signal_url) {initPC();var offer = await pc.createOffer();await pc.setLocalDescription(offer);let sendOfferPromise = await fetch(signal_url, {"method": "POST","body": JSON.stringify(offer)});if (sendOfferPromise.ok) {console.log("send offer: " + JSON.stringify(offer)); } else {alert("HTTP-Error: " + sendOfferPromise.status);} } async function nfyFromSignal(nfyPromise) {let nfyString = await nfyPromise.text();if (nfyString.includes("answer")) {console.log("receive answer: " + nfyString);pc.setRemoteDescription(new RTCSessionDescription(JSON.parse(nfyString)));} else if (nfyString.includes("candidate")) {console.log("receive candidate: " + nfyString);pc.addIceCandidate(new RTCIceCandidate(JSON.parse(nfyString)));} else {let peersString = nfyString;// console.log("rsp: ", peersString)let peersChunk = peersString.split("\n");for (let i=0; i<peersChunk.length && peersChunk[i].length>0; ++i) {const peerColumns = peersChunk[i].split(",");// console.log("index: " + i + ", data: " + peerColumns)// for example: kevin@home-pc,36,1// peerColumns[0]: peer_name// peerColumns[1]: peer_id// peerColumns[2]: peer_status// table's column index starts from 1, not 0const row_find_peer_id = $("#PeersTable tr:has(td:nth-child(2):contains('" + peerColumns[1] + "'))");if (row_find_peer_id.length > 0) {console.log("peerid:" + peerColumns[1] + ", status change from " + row_find_peer_id.find('td:nth-child(3)').text() + " to " + peerColumns[2]);row_find_peer_id.find('td:nth-child(3)').text(peerColumns[2]);continue;}const row_find_peer_name = $("#PeersTable tr:has(td:nth-child(1):contains('" + peerColumns[0] + "'))");if (row_find_peer_name.length > 0) {console.log("peerid:" + peerColumns[1] + ", status change from " + row_find_peer_name.find('td:nth-child(3)').text() + " to " + peerColumns[2]);row_find_peer_name.find('td:nth-child(2)').text(peerColumns[1]);row_find_peer_name.find('td:nth-child(3)').text(peerColumns[2]);continue;} const row_peer = $("<tr>");row_peer.append($("<td>").text(peerColumns[0]));row_peer.append($("<td>").text(peerColumns[1]));row_peer.append($("<td>").text(peerColumns[2]));$("#PeersTable").append(row_peer);} }}async function pendingWait(myself_peerid) {const signal_url = document.getElementById("signal_url").value;while (true) {let v = await fetch(`http://${signal_url}/wait?peer_id=${myself_peerid}`);nfyFromSignal(v);}}$('#btn_sign_in').on('click', async () => {const signal_url = document.getElementById("signal_url").value;let signinResultPromise = await fetch(`http://${signal_url}/sign_in`);if (signinResultPromise.ok) {myselfPeerId = parseInt(signinResultPromise.headers.get("Pragma"));console.log("my peerid is: " + myselfPeerId);nfyFromSignal(signinResultPromise);pendingWait(myselfPeerId); } else {alert("HTTP-Error: " + signinResultPromise.status);}}) $('#btn_sign_out').on('click', async () => {$("#PeersTable tbody").empty();const signal_url = document.getElementById("signal_url").value;let signoutResultPromise = await fetch(`http://${signal_url}/sign_out?peer_id=${myselfPeerId}`);if (signoutResultPromise.ok) {console.log("sign_out: " + myselfPeerId + " successful"); } else {alert("HTTP-Error: " + signoutResultPromise.status);}})$('#PeersTable').on('click', 'tr', function() {const row_selected = $(this);const row_selected_peer_id = parseInt(row_selected.find('td:nth-child(2)').text());if (row_selected_peer_id === myselfPeerId) {console.log("You should not choose yourself [" + myselfPeerId + "] to start p2p");$("#btn_start_p2p").prop("disabled", true);return;}const row_selected_peer_id_status = parseInt(row_selected.find('td:nth-child(3)').text());if (row_selected_peer_id_status === 1) {console.log("selected peerid: " + row_selected_peer_id);$('#selected_peerid_for_p2p').val(row_selected_peer_id);$("#btn_start_p2p").prop("disabled", false); } else {console.log("The peer [" + row_selected_peer_id + "] you choose is offline");$("#btn_start_p2p").prop("disabled", true);}})$('#btn_start_p2p').on('click', async () => {const signal_url = document.getElementById("signal_url").value;const remote_peer_id = $('#selected_peerid_for_p2p').val();const sendmsg_url = `http://${signal_url}/message?peer_id=${myselfPeerId}&to=${remote_peer_id}`;console.log("sendmsg url: " + sendmsg_url);// $('#rtc_video_play').show();// $('#rtc_video_play').prop('muted', false);$('#rtc_video_play').prop('srcObject', stream);console.log("Start P2P from [" + myselfPeerId + "] to [" + remote_peer_id + "]");startP2P(sendmsg_url);})</script>
</body>
</html>
