WebRTC 发送消息
WebRTC 发送消息
现在我们创建一个简单的例子. 首先, 运行信令服务器(signaling server).
页面上包含三个文本输入框,一个用来登录,一个用来输入用户名,一个用于填写你要发送给其他计算机的消息,创建index.html并添加如下代码:
<html lang="en"> <head> <meta charset="utf-8" /> </head> <body> <div> <input type="text" id="loginInput" /> <button id="loginBtn">Login</button> </div> <div> <input type="text" id="otherUsernameInput" /> <button id="connectToOtherUsernameBtn">Establish connection</button> </div> <div> <input type="text" id="msgInput" /> <button id="sendMsgBtn">Send text message</button> </div> <script src="client.js"></script> </body> </html>
我们还要添加三个按钮:用于登,建立连接和发送消息。创建一个client.js文件并添加以下代码:
var connection = new WebSocket('ws://localhost:9090');
var name = "";
var loginInput = document.querySelector('#loginInput');
var loginBtn = document.querySelector('#loginBtn');
var otherUsernameInput = document.querySelector('#otherUsernameInput');
var connectToOtherUsernameBtn = document.querySelector('#connectToOtherUsernameBtn');
var msgInput = document.querySelector('#msgInput');
var sendMsgBtn = document.querySelector('#sendMsgBtn');
var connectedUser, myConnection, dataChannel;
//when a user clicks the login button
loginBtn.addEventListener("click", function(event) {
name = loginInput.value;
if(name.length > 0) {
send({
type: "login",
name: name
});
}
});
//handle messages from the server
connection.onmessage = function (message) {
console.log("Got message", message.data);
var data = JSON.parse(message.data);
switch(data.type) {
case "login":
onLogin(data.success);
break;
case "offer":
onOffer(data.offer, data.name);
break;
case "answer":
onAnswer(data.answer);
break;
case "candidate":
onCandidate(data.candidate);
break;
default:
break;
}
};
//when a user logs in
function onLogin(success) {
if (success === false) {
alert("oops...try a different username");
} else {
//creating our RTCPeerConnection object
var configuration = {
"iceServers": [{ "url": "stun:stun.1.google.com:19302" }]
};
myConnection = new webkitRTCPeerConnection(configuration, {
optional: [{RtpDataChannels: true}]
});
console.log("RTCPeerConnection object was created");
console.log(myConnection);
//setup ice handling
//when the browser finds an ice candidate we send it to another peer
myConnection.onicecandidate = function (event) {
if (event.candidate) {
send({
type: "candidate",
candidate: event.candidate
});
}
};
openDataChannel();
}
};
connection.onopen = function () {
console.log("Connected");
};
connection.onerror = function (err) {
console.log("Got error", err);
};
// Alias for sending messages in JSON format
function send(message) {
if (connectedUser) {
message.name = connectedUser;
}
connection.send(JSON.stringify(message));
};您可以看到,我们建立了一个与信令服务器的连接。当用户单击登录按钮时,程序将把用户名发送给服务器。如果登录成功,应用程序将创建RTCPeerConnection对象并设置OnIceCandidate处理程序,它将所有找到的IceCandidates发送到另一个对等点。它还运行创建DataChannel的opendatachannel()函数。请注意,在创建RTCPeerConnection对象时,构造函数可选:[{rtpdatachannels:true}]中的第二个参数是强制使用chrome或opera浏览器.下一步是为其他节点创建一个提议。将以下代码添加到client.js文件中:
//setup a peer connection with another user
connectToOtherUsernameBtn.addEventListener("click", function () {
var otherUsername = otherUsernameInput.value;
connectedUser = otherUsername;
if (otherUsername.length > 0) {
//make an offer
myConnection.createOffer(function (offer) {
console.log();
send({
type: "offer",
offer: offer
});
myConnection.setLocalDescription(offer);
}, function (error) {
alert("An error has occurred.");
});
}
});
//when somebody wants to call us
function onOffer(offer, name) {
connectedUser = name;
myConnection.setRemoteDescription(new RTCSessionDescription(offer));
myConnection.createAnswer(function (answer) {
myConnection.setLocalDescription(answer);
send({
type: "answer",
answer: answer
});
}, function (error) {
alert("oops...error");
});
}
//when another user answers to our offer
function onAnswer(answer) {
myConnection.setRemoteDescription(new RTCSessionDescription(answer));
}
//when we got ice candidate from another user
function onCandidate(candidate) {
myConnection.addIceCandidate(new RTCIceCandidate(candidate));
}您可以看到,当单击“建立连接”按钮时,程序会向其他节点提供SDP提议。我们还设置了onanswer和oncandidate处理程序。最后,让我们实现创建datachannel的opendatachannel()函数。将以下代码添加到client.js文件中:
//creating data channel
function openDataChannel() {
var dataChannelOptions = {
reliable:true
};
dataChannel = myConnection.createDataChannel("myDataChannel", dataChannelOptions);
dataChannel.onerror = function (error) {
console.log("Error:", error);
};
dataChannel.onmessage = function (event) {
console.log("Got message:", event.data);
};
}
//when a user clicks the send message button
sendMsgBtn.addEventListener("click", function (event) {
console.log("send message");
var val = msgInput.value;
dataChannel.send(val);
});在这里,我们为连接创建datachannel,并为“发送消息”按钮添加事件处理程序。现在,在两个选项卡中打开此页面,使用两个用户登录,建立连接,并尝试发送消息,您应该在控制台输出中看到它们。请注意上面的示例在opera中测试的。
