Netty入门: 基于netty的websocket聊天室

时间 2021-04-28 标签 javascript html 前端 java web 浏览器服务器 websocket 异步 socket

项目结构

服务端

public class MyServer {
 public static void main(String[] args) throws Exception{
 // 负责链接的NioEventLoopGroup线程数为1
 EventLoopGroup bossGroup = new NioEventLoopGroup(1);
 EventLoopGroup wokerGroup = new NioEventLoopGroup();

 try{
 ServerBootstrap serverBootstrap = new ServerBootstrap();
 serverBootstrap.group(bossGroup,wokerGroup).channel(NioServerSocketChannel.class)
 // 加入日志
 .handler(new LoggingHandler(LogLevel.INFO))
 // 自定义channel初始化器
 .childHandler(new WebSocketChannelInitializer());
 // 绑定本机的8005端口
 ChannelFuture channelFuture = serverBootstrap.bind(new InetSocketAddress(8005)).sync();
 // 异步回调-关闭事件
 channelFuture.channel().closeFuture().sync();
 }finally {
 bossGroup.shutdownGracefully();
 wokerGroup.shutdownGracefully();
 }

 }

channel初始化器javascript

public class WebSocketChannelInitializer extends ChannelInitializer<SocketChannel> {
 @Override
 protected void initChannel(SocketChannel ch) throws Exception {
 ChannelPipeline pipeline = ch.pipeline();
 //websocket协议自己是基于http协议的，因此这边也要使用http解编码器
 pipeline.addLast(new HttpServerCodec());
 //以块的方式来写的处理器
 pipeline.addLast(new ChunkedWriteHandler());
 //netty是基于分段请求的，HttpObjectAggregator的做用是将请求分段再聚合,参数是聚合字节的最大长度
 pipeline.addLast(new HttpObjectAggregator(8192));

 // 使用websocket协议
 //ws://server:port/context_path
 //参数指的是contex_path
 pipeline.addLast(new WebSocketServerProtocolHandler("/world"));
 //websocket定义了传递数据的中frame类型
 pipeline.addLast(new TextWebSocketFrameHandler());
 }
}

WebSocketChannelInitializerchannel初始化器html

public class WebSocketChannelInitializer extends ChannelInitializer<SocketChannel> {
 @Override
 protected void initChannel(SocketChannel ch) throws Exception {
 ChannelPipeline pipeline = ch.pipeline();
 //websocket协议自己是基于http协议的，因此这边也要使用http解编码器
 pipeline.addLast(new HttpServerCodec());
 //以块的方式来写的处理器
 pipeline.addLast(new ChunkedWriteHandler());
 //netty是基于分段请求的，HttpObjectAggregator的做用是将请求分段再聚合,参数是聚合字节的最大长度
 pipeline.addLast(new HttpObjectAggregator(8192));

 // 使用websocket协议
 //ws://server:port/context_path
 //参数指的是contex_path
 pipeline.addLast(new WebSocketServerProtocolHandler("/world"));
 //websocket定义了传递数据的中frame类型，这里使用TextWebSocketFrame并自定义一个handler
 pipeline.addLast(new TextWebSocketFrameHandler());
 }
}

public class TextWebSocketFrameHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
 /**
 * 通道列表 用于存放通道
 */
 public static CopyOnWriteArrayList<Channel> channelList = new CopyOnWriteArrayList<Channel>();

 @Override
 protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {

 /**
 * writeAndFlush接收的参数类型是Object类型，可是通常咱们都是要传入管道中传输数据的类型，好比咱们当前的demo
 * 传输的就是TextWebSocketFrame类型的数据
 */
 System.out.println(msg.text());
 // 遍历通道list，向非当前通道发送消息
 channelList.forEach(channel -> {
 if (channel != ctx.channel()){
 channel.writeAndFlush(new TextWebSocketFrame(ctx.channel().id().asShortText()+":" +msg.text()));
 }
 else {
 channel.writeAndFlush(new TextWebSocketFrame("我:" +msg.text()));
 }
 }
 );
 }

 /**
 * channel add后触发,向channelList添加新加入的通道
 *
 * @param ctx ctx
 * @throws Exception 异常
 */
 @Override
 public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
 channelList.forEach(channel -> channel.writeAndFlush(new TextWebSocketFrame(ctx.channel().id().asShortText()+"上线了")));
 channelList.add(ctx.channel());
 }

 /**
 * channel链接断开时触发，猜想是TCP断开时触发回调 发送链接断开事件
 *
 * @param ctx ctx
 * @throws Exception 异常
 */
 @Override
 public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
 channelList.forEach(channel -> channel.writeAndFlush(new TextWebSocketFrame(ctx.channel().id().asShortText()+"下线了")));
 }

 @Override
 public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
 System.out.println("异常发生");
 ctx.close();
 }

TextWebSocketFrameHandler继承了SimpleChannelInboundHandler,SimpleChannelInboundHandler其实是一个ChannelHandlerAdapter，其方法会在入站的时候被调用。这里咱们经过重写handlerAdded方法，在通道建立后将其加入当channelList中，并向其他通道发送成员上线的提示信息。重写channelRead0方法，向全部非当前channel发送读取到消息。前端

前端java

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>WebSocket客户端</title>
</head>
<body>
<script type="text/javascript">
 var socket;
 //若是浏览器支持WebSocket
 if(window.WebSocket){
        //参数就是与服务器链接的地址
 socket = new WebSocket("ws://localhost:8005/world");
 //客户端收到服务器消息的时候就会执行这个回调方法
 socket.onmessage = function (event) {
            var ta = document.getElementById("responseText");
 ta.value = ta.value + "n"+event.data;
 }
        //链接创建的回调函数
 socket.onopen = function(event){
            var ta = document.getElementById("responseText");
 ta.value = "链接开启";
 }
        //链接断掉的回调函数
 socket.onclose = function (event) {
            var ta = document.getElementById("responseText");
 ta.value = ta.value +"n"+"链接关闭";
 }
    }else{
        alert("浏览器不支持WebSocket！");
 }
    //发送数据
 function send(message){
        if(!window.WebSocket){
            return;
 }
        //当websocket状态打开
 if(socket.readyState == WebSocket.OPEN){
            socket.send(message);
 }else{
            alert("链接没有开启");
 }
    }
</script>
<form onsubmit="return false">
 <textarea name = "message" style="width: 400px;height: 200px"></textarea>
 <input type ="button" value="发送数据" onclick="send(this.form.message.value);">
 <h3>服务器输出：</h3>
 <textarea id ="responseText" style="width: 400px;height: 300px;"></textarea>
 <input type="button" onclick="javascript:document.getElementById('responseText').value=''" value="清空数据">
</form>
</body>
</html>

Netty入门: 基于netty的websocket聊天室

项目结构

服务端

测试