Java基于websocket协议与netty实时视频弹幕交互实现
作者：兴趣使然的程序猿
摘要
2021年了，还有不支持弹幕的视频网站吗，现在各种弹幕玩法层出不穷，抽奖，ppt都上弹幕玩法了，不整个弹幕都说不过去了，今天笔者就抽空做了一个实时视频弹幕交互功能的实现，不得不说这样的形式为看视频看直播，讲义PPT，抽奖等形式增加了许多乐趣。
1 技术选型
1.1 netty
官方对于netty的描述：netty官网.
Netty is an asynchronous event-driven network application framework
for rapid development of maintainable high performance protocol servers & clients.
Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients. It greatly simplifies and streamlines network programming such as TCP and UDP socket server.
‘Quick and easy' doesn't mean that a resulting application will suffer from a maintainability or a performance issue. Netty has been designed carefully with the experiences earned from the implementation of a lot of protocols such as FTP, SMTP, HTTP, and various binary and text-based legacy protocols. As a result, Netty has succeeded to find a way to achieve ease of development, performance, stability, and flexibility without a compromise.1
主要关键词描述：netty是异步事件驱动网络框架，可做各种协议服务端，并且支持了FTP，SMTP，HTTP等很多协议，并且性能，稳定性，灵活性都很棒。
可以看到netty整体架构上分了三个部分：
a. 以零拷贝，一致性接口，扩展事件模型的底层核心。
b. Socket，Datagram，Pipe，Http Tunnel作为传输媒介。
c. 传输支持的各种协议，HTTP&WebSocket，SSL，大文件，zlib/gzip压缩，文本，二进制，Google Protobuf等各种各种的传输形式。
1.2 WebSocket
WebSocket是一种在单个TCP连接上进行全双工通信的协议。WebSocket通信协议于2011年被IETF定为标准RFC 6455，并由RFC7936补充规范。WebSocket API也被W3C定为标准。
WebSocket使得客户端和服务器之间的数据交换变得更加简单，允许服务端主动向客户端推送数据。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，并进行双向数据传输。2
1.3 为什么做这样的技术选型。
a. 由上述可知，实时直播交互作为互动式是一个双向数据传输过程。所以使用webSocket。
b. netty本身支持了webSocket协议的实现，让实现更加简单方便。
2 实现思路
2.1 服务架构
整体架构是所有客户端都和我的服务端开启一个双向通道的架构。
2.2 传输流程
3 实现效果
3.1 视频展示
先看看效果吧，是不是perfect，接下来就来看具体代码是怎么实现的吧。
视频直播弹幕示例
4 代码实现
4.1 项目结构
一个maven项目，将代码放一个包下就行。
4.2 Java服务端
Java服务端代码，总共三个类，Server，Initailizer和 Handler。
4.2.1 先做一个netty nio的服务端：
一个nio的服务，开启一个tcp端口。
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
* Copyright(c)lbhbinhao@163.com
* @author liubinhao
* @date 2021/1/14
* ++++ ______ ______ ______
* +++/ /| / /| / /|
* +/_____/ | /_____/ | /_____/ |
* | | | | | | | | |
* | | | | | |________| | |
* | | | | | / | | |
* | | | | |/___________| | |
* | | |___________________ | |____________| | |
* | | / / | | | | | | |
* | |/ _________________/ / | | / | | /
* |_________________________|/b |_____|/ |_____|/
*/
public enum BulletChatServer {
/**
* Server instance
*/
SERVER;
private BulletChatServer(){
EventLoopGroup mainGroup = new NioEventLoopGroup();
EventLoopGroup subGroup = new NioEventLoopGroup();
ServerBootstrap server = new ServerBootstrap();
server.group(mainGroup,subGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new BulletChatInitializer());
ChannelFuture future = server.bind(9123);
}
public static void main(String[] args) {
}
}
4.2.2 服务端的具体处理逻辑
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.stream.ChunkedWriteHandler;
import io.netty.handler.timeout.IdleStateHandler;
/**
* Copyright(c)lbhbinhao@163.com
*
* @author liubinhao
* @date 2021/1/14
* ++++ ______ ______ ______
* +++/ /| / /| / /|
* +/_____/ | /_____/ | /_____/ |
* | | | | | | | | |
* | | | | | |________| | |
* | | | | | / | | |
* | | | | |/___________| | |
* | | |___________________ | |____________| | |
* | | / / | | | | | | |
* | |/ _________________/ / | | / | | /
* |_________________________|/b |_____|/ |_____|/
*/
public class BulletChatInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new HttpServerCodec());
pipeline.addLast(new ChunkedWriteHandler());
pipeline.addLast(new HttpObjectAggregator(1024*64));
pipeline.addLast(new IdleStateHandler(8, 10, 12));
pipeline.addLast(new WebSocketServerProtocolHandler("/lbh"));
pipeline.addLast(new BulletChatHandler());
}
}
[^
后台处理逻辑，接受到消息，写出到所有的客户端：
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.concurrent.EventExecutorGroup;
import io.netty.util.concurrent.GlobalEventExecutor;
/**
* Copyright(c)lbhbinhao@163.com
*
* @author liubinhao
* @date 2021/1/14
* ++++ ______ ______ ______
* +++/ /| / /| / /|
* +/_____/ | /_____/ | /_____/ |
* | | | | | | | | |
* | | | | | |________| | |
* | | | | | / | | |
* | | | | |/___________| | |
* | | |___________________ | |____________| | |
* | | / / | | | | | | |
* | |/ _________________/ / | | / | | /
* |_________________________|/b |_____|/ |_____|/
*/
public class BulletChatHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
// 用于记录和管理所有客户端的channel
public static ChannelGroup channels =
new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
@Override
protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
// 获取客户端传输过来的消息
String content = msg.text();
System.err.println("收到消息："+ content);
channels.writeAndFlush(new TextWebSocketFrame(content));
System.err.println("写出消息完成："+content);
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
channels.add(ctx.channel());
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
String channelId = ctx.channel().id().asShortText();
System.out.println("客户端被移除，channelId为：" + channelId);
channels.remove(ctx.channel());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
// 发生异常之后关闭连接（关闭channel），随后从ChannelGroup中移除
ctx.channel().close();
channels.remove(ctx.channel());
}
}
4.3 网页客户端实现
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Netty视频弹幕实现 Author:Binhao Liu</title>
<link rel="stylesheet" href="">
<style type="text/css" media="screen">
* {
margin: 0px;
padding: 0px
}
html, body {
height: 100%
}
body {
overflow: hidden;
background-color: #FFF;
text-align: center;
}
.flex-column {
display: flex;
flex-direction: column;
justify-content: space-between;, align-items: center;
}
.flex-row {
display: flex;
flex-direction: row;
justify-content: center;
align-items: center;
}
.wrap {
overflow: hidden;
width: 70%;
height: 600px;
margin: 100px auto;
padding: 20px;
background-color: transparent;
box-shadow: 0 0 9px #222;
border-radius: 20px;
}
.wrap .box {
position: relative;
width: 100%;
height: 90%;
background-color: #000000;
border-radius: 10px
}
.wrap .box span {
position: absolute;
top: 10px;
left: 20px;
display: block;
padding: 10px;
color: #336688
}
.wrap .send {
display: flex;
width: 100%;
height: 10%;
background-color: #000000;
border-radius: 8px
}
.wrap .send input {
width: 40%;
height: 60%;
border: 0;
outline: 0;
border-radius: 5px 0px 0px 5px;
box-shadow: 0px 0px 5px #d9d9d9;
text-indent: 1em
}
.wrap .send .send-btn {
width: 100px;
height: 60%;
background-color: #fe943b;
color: #FFF;
text-align: center;
border-radius: 0px 5px 5px 0px;
line-height: 30px;
cursor: pointer;
}
.wrap .send .send-btn:hover {
background-color: #4cacdc
}
</style>
</head>
<script>
var ws = new WebSocket("ws://localhost:9123/lbh");
ws.onopen = function () {
// Web Socket 已连接上，使用 send() 方法发送数据
alert("数据发送中...");
};
ws.onmessage = function (e) {
console.log("接受到消息:"+e.data);
createEle(e.data);
};
ws.onclose = function () {
// 关闭 websocket
alert("连接已关闭...");
};
function sendMsg(msg) {
ws.send(msg)
}
</script>
<body>
<div class="wrap flex-column">
<div class="box">
<video src="shape.mp4" width="100%" height="100%" controls autoplay></video>
</div>
<div class="send flex-row">
<input type="text" class="con" placeholder="弹幕发送[]~(^v^)~*"/>
<div class="send-btn" onclick="javascript:sendMsg(document.querySelector('.con').value)">发送</div>
</div>
</div>
<script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js" type="text/javascript"></script>
<script>
//1.获取元素
var oBox = document.querySelector('.box'); //获取.box元素
var cW = oBox.offsetWidth; //获取box的宽度
var cH = oBox.offsetHeight; //获取box的高度
function createEle(txt) {
//动态生成span标签
var oMessage = document.createElement('span'); //创建标签
oMessage.innerHTML = txt; //接收参数txt并且生成替换内容
oMessage.style.left = cW + 'px'; //初始化生成位置x
oBox.appendChild(oMessage); //把标签塞到oBox里面
roll.call(oMessage, {
//call改变函数内部this的指向
timing: ['linear', 'ease-out'][~~(Math.random() * 2)],
color: '#' + (~~(Math.random() * (1 << 24))).toString(16),
top: random(0, cH),
fontSize: random(16, 32)
});
}
function roll(opt) {
//弹幕滚动
//如果对象中不存在timing 初始化
opt.timing = opt.timing || 'linear';
opt.color = opt.color || '#fff';
opt.top = opt.top || 0;
opt.fontSize = opt.fontSize || 16;
this._left = parseInt(this.offsetLeft); //获取当前left的值
this.style.color = opt.color; //初始化颜色
this.style.top = opt.top + 'px';
this.style.fontSize = opt.fontSize + 'px';
this.timer = setInterval(function () {
if (this._left <= 100) {
clearInterval(this.timer); //终止定时器
this.parentNode.removeChild(this);
return; //终止函数
}
switch (opt.timing) {
case 'linear': //如果匀速
this._left += -2;
break;
case 'ease-out': //
this._left += (0 - this._left) * .01;
break;
}
this.style.left = this._left + 'px';
}.bind(this), 1000 / 60);
}
function random(start, end) {
//随机数封装
return start + ~~(Math.random() * (end - start));
}
var aLi = document.querySelectorAll('li'); //10
function forEach(ele, cb) {
for (var i = 0, len = aLi.length; i < len; i++) {
cb && cb(ele[i], i);
}
}
forEach(aLi, function (ele, i) {
ele.style.left = i * 100 + 'px';
});
//产生闭包
var obj = {
num: 1,
add: function () {
this.num++; //obj.num = 2;
(function () {
console.log(this.num);
})
}
};
obj.add();//window
</script>
</body>
</html>
这样一个实时的视频弹幕功能就完成啦，是不是很简单，各位小伙伴快来试试吧。
5 小结
上班撸代码，下班继续撸代码写博客，这个还是很简单，笔者写这个的时候一会儿就写完了，不过这也得益于笔者很久以前就写过netty的服务，对于Http，Tcp之类协议也比较熟悉，只有前端会有些难度，问下度娘，也很快能做完，在此分享出来与诸君分享。
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