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Spring Boot + Netty + WebSocket 实现消息推送

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1

关于Netty


Netty 是一个利用 Java 的高级网络的能力,隐藏其背后的复杂性而提供一个易于使用的 API 的客户端/服务器框架。



2

Maven依赖


<dependencies>
 <!-- https://mvnrepository.com/artifact/io.netty/netty-all -->
 <dependency>
  <groupId>io.netty</groupId>
  <artifactId>netty-all</artifactId>
  <version>4.1.36.Final</version>
 </dependency>
</dependencies>



3

SpringBootApplication


启动器中需要new一个NettyServer,并显式调用启动netty。


@SpringBootApplication
public class SpringCloudStudyDemoApplication {
 public static void main(String[] args) {
  SpringApplication.run(SpringCloudStudyDemoApplication.class,args);
  try {
   new NettyServer(12345).start();
   System.out.println("https://blog.csdn.net/moshowgame");
   System.out.println("http://127.0.0.1:6688/netty-websocket/index");
  }catch(Exception e) {
   System.out.println("NettyServerError:"+e.getMessage());
  }
 }
}



4

NettyServer


启动的NettyServer,这里进行配置


/**
 * NettyServer Netty服务器配置
 */

public class NettyServer {

    private final int port;

    public NettyServer(int port) {
        this.port = port;
    }

    public void start() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup group = new NioEventLoopGroup();

        try {
            ServerBootstrap sb = new ServerBootstrap();
            sb.option(ChannelOption.SO_BACKLOG, 1024);
            sb.group(group, bossGroup) // 绑定线程池
                    .channel(NioServerSocketChannel.class) // 指定使用的channel
                    .localAddress(this.port)// 绑定监听端口
                    .childHandler(new ChannelInitializer<SocketChannel>() { // 绑定客户端连接时候触发操作
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception
{
                            System.out.println("收到新连接");

                            //websocket协议本身是基于http协议的,所以这边也要使用http解编码器
                            ch.pipeline().addLast(new HttpServerCodec());

                            //以块的方式来写的处理器
                            ch.pipeline().addLast(new ChunkedWriteHandler());
                            ch.pipeline().addLast(new HttpObjectAggregator(8192));
                            ch.pipeline().addLast(new WebSocketServerProtocolHandler("/ws", null, true, 65536 * 10));
                            ch.pipeline().addLast(new MyWebSocketHandler());
                        }
                    });

            ChannelFuture cf = sb.bind().sync(); // 服务器异步创建绑定
            System.out.println(NettyServer.class + " 启动正在监听:" + cf.channel().localAddress());
            cf.channel().closeFuture().sync(); // 关闭服务器通道
        } finally {
            group.shutdownGracefully().sync(); // 释放线程池资源
            bossGroup.shutdownGracefully().sync();
        }
    }
}



5

MyChannelHandlerPool


通道组池,管理所有websocket连接


/**
 * MyChannelHandlerPool
 * 通道组池,管理所有websocket连接
 */

public class MyChannelHandlerPool {

    public MyChannelHandlerPool(){}

    public static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
}



6

MyWebSocketHandler


处理ws一下几种情况:


  • channelActive与客户端建立连接

  • channelInactive与客户端断开连接

  • channelRead0客户端发送消息处理


/**
 * NettyServer Netty服务器配置
 */

public class NettyServer {

    private final int port;

    public NettyServer(int port) {
        this.port = port;
    }

    public void start() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            ServerBootstrap sb = new ServerBootstrap();
            sb.option(ChannelOption.SO_BACKLOG, 1024);
            sb.group(group, bossGroup) // 绑定线程池
                    .channel(NioServerSocketChannel.class) // 指定使用的channel
                    .localAddress(this.port)// 绑定监听端口
                    .childHandler(new ChannelInitializer<SocketChannel>() { // 绑定客户端连接时候触发操作

                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception
{
                            System.out.println("收到新连接");
                            //websocket协议本身是基于http协议的,所以这边也要使用http解编码器
                            ch.pipeline().addLast(new HttpServerCodec());
                            //以块的方式来写的处理器
                            ch.pipeline().addLast(new ChunkedWriteHandler());
                            ch.pipeline().addLast(new HttpObjectAggregator(8192));
                            ch.pipeline().addLast(new WebSocketServerProtocolHandler("/ws", "WebSocket", true, 65536 * 10));
                            ch.pipeline().addLast(new MyWebSocketHandler());
                        }
                    });

            ChannelFuture cf = sb.bind().sync(); // 服务器异步创建绑定
            System.out.println(NettyServer.class + " 启动正在监听:" + cf.channel().localAddress());
            cf.channel().closeFuture().sync(); // 关闭服务器通道
        } finally {
            group.shutdownGracefully().sync(); // 释放线程池资源
            bossGroup.shutdownGracefully().sync();
        }
    }
}



7

socket.html


主要是连接ws,发送消息,以及消息反馈


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Netty-Websocket</title>
    <script type="text/javascript">
        // by zhengkai.blog.csdn.net
        var socket;
        if(!window.WebSocket){
            window.WebSocket = window.MozWebSocket;
        }

        if(window.WebSocket){
            socket = new WebSocket("ws://127.0.0.1:12345/ws");
            socket.onmessage = function(event){
                var ta = document.getElementById('responseText');
                ta.value += event.data+"rn";
            };
            socket.onopen = function(event){
                var ta = document.getElementById('responseText');
                ta.value = "Netty-WebSocket服务器。。。。。。连接 rn";
            };
            socket.onclose = function(event){
                var ta = document.getElementById('responseText');
                ta.value = "Netty-WebSocket服务器。。。。。。关闭 rn";
            };
        }else{
            alert("您的浏览器不支持WebSocket协议!");
        }

        function send(message){
            if(!window.WebSocket){return;}
            if(socket.readyState == WebSocket.OPEN){
                socket.send(message);
            }else{
                alert("WebSocket 连接没有建立成功!");
            }
        }
    </script>
</head>
<body>
<form onSubmit="return false;">
    <label>ID</label><input type="text" name="uid" value="${uid!!}" /> <br />
    <label>TEXT</label><input type="text" name="message" value="这里输入消息" /> <br />
    <br /> <input type="button" value="发送ws消息"
                  onClick="send(this.form.uid.value+':'+this.form.message.value)" />

    <hr color="black" />
    <h3>服务端返回的应答消息</h3>
    <textarea id="responseText" style="width: 1024px;height: 300px;"></textarea>
</form>
</body>
</html>



8

Controller


写好了html当然还需要一个controller来引导页面。


@RestController
public class IndexController {

 @GetMapping("/index")
 public ModelAndView index(){
  ModelAndView mav=new ModelAndView("socket");
  mav.addObject("uid", RandomUtil.randomNumbers(6));
  return mav;
 }
}


 

9

效果演示






10

改造netty支持url参数


1.首先,调整一下加载handler的顺序,优先MyWebSocketHandler在WebSocketServerProtocolHandler之上。


ch.pipeline().addLast(new MyWebSocketHandler());
ch.pipeline().addLast(new WebSocketServerProtocolHandler("/ws", null, true, 65536 * 10));


2.其次,改造MyWebSocketHandler 的channelRead方法,首次连接会是一个FullHttpRequest类型,可以通过FullHttpRequest.uri()获取完整ws的URL地址,之后接受信息的话,会是一个TextWebSocketFrame类型。


public class MyWebSocketHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("与客户端建立连接,通道开启!");

        //添加到channelGroup通道组
        MyChannelHandlerPool.channelGroup.add(ctx.channel());
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("与客户端断开连接,通道关闭!");

        //添加到channelGroup 通道组
        MyChannelHandlerPool.channelGroup.remove(ctx.channel());
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        //首次连接是FullHttpRequest,处理参数 by zhengkai.blog.csdn.net
        if (null != msg && msg instanceof FullHttpRequest) {
            FullHttpRequest request = (FullHttpRequest) msg;
            String uri = request.uri();
            Map paramMap=getUrlParams(uri);
            System.out.println("接收到的参数是:"+JSON.toJSONString(paramMap));
            //如果url包含参数,需要处理
            if(uri.contains("?")){
                String newUri=uri.substring(0,uri.indexOf("?"));
                System.out.println(newUri);
                request.setUri(newUri);
            }
        }else if(msg instanceof TextWebSocketFrame){
            //正常的TEXT消息类型
            TextWebSocketFrame frame=(TextWebSocketFrame)msg;
            System.out.println("客户端收到服务器数据:" +frame.text());
            sendAllMessage(frame.text());
        }
        super.channelRead(ctx, msg);
    }

    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, TextWebSocketFrame textWebSocketFrame) throws Exception {

    }

    private void sendAllMessage(String message){
        //收到信息后,群发给所有channel
        MyChannelHandlerPool.channelGroup.writeAndFlush( new TextWebSocketFrame(message));
    }

    private static Map getUrlParams(String url){
        Map<String,String> map = new HashMap<>();
        url = url.replace("?",";");
        if (!url.contains(";")){
            return map;
        }

        if (url.split(";").length > 0){
            String[] arr = url.split(";")[1].split("&");
            for (String s : arr){
                String key = s.split("=")[0];
                String value = s.split("=")[1];
                map.put(key,value);
            }
            return  map;
        }else{
            return map;
        }
    }
}


3.html中的ws地址也进行改造


socket = new WebSocket("ws://127.0.0.1:12345/ws?uid=666&gid=777");


4.改造后控制台输出情况


收到新连接
与客户端建立连接,通道开启!
接收到的参数是:{"uid":"666","gid":"777"}
/ws
客户端收到服务器数据:142531:这里输入消息
客户端收到服务器数据:142531:这里输入消息
客户端收到服务器数据:142531:这里输入消息


failed: WebSocket opening handshake timed out


听说是ssl wss的情况下才会出现,来自 @around-gao 的解决方法:


把MyWebSocketHandler和WebSocketServerProtocolHandler调下顺序就好了。


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