PHP 程序员也能做的 Java 开发 30分钟使用 netty 轻松打造一个高性能 websocket 服务

周梦康

硬广一波

SF 官方首页推荐《PHP进阶之路》(你又多久没有投资自己了?先看后买)

我们下面则将一些实际场景都添加进去,比如用户身份的验证,游客只能浏览不能发言,多房间(频道)的聊天。
该博客非常适合 Java 新手,非常适合作为学习 Java 的切入点,不需要考虑tomcat、spring、mybatis等。
唯一的知识点就是 maven 的基础使用。

完整的代码地址

https://github.com/zhoumengka...

├── WebSocketServer.java                启动服务器端口监听
├── WebSocketServerInitializer.java     初始化服务
├── WebSocketServerHandler.java         接管WebSocket数据连接
├── dto
│   └── Response.java                   返回给客户端数据对象
├── entity
│   └── Client.java                     每个连接到WebSocket服务的客户端对象
└── service
    ├── MessageService.java             完成发送消息
    └── RequestService.java             WebSocket初始化连接握手时的数据处理

功能设计概述

身份认证

客户端将用户 id 、进入的房间的 rid、用户 token json_encode,例如{id:1;rid:21;token:'43606811c7305ccc6abb2be116579bfd'}。然后在 base64 处理,通过参数request传到服务器,然后在服务器做 id 和 token 的验证(我的做法是 token 存放在redis string 5秒的过期时间)

房间表

使用一个Map channelGroupMap 来存放各个房间(频道),以客户端传握手时传过来的 base64 字符串中获取到定义的房间 ID,然后为该房间 ID 新建一个ChannelGroupChannelGroup 方便对该组内的所有客户端广播消息)

在 pom.xml 中引入netty 5

现在大家都有自己的包管理工具,不需要实现下载了然后放到本地lib库中,和 nodejs 的 npm, php 的 compser 一样。

<dependencies>
    <dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-all</artifactId>
        <version>5.0.0.Alpha2</version>
    </dependency>
    <dependency>
        <groupId>com.jcraft</groupId>
        <artifactId>jzlib</artifactId>
        <version>1.1.2</version>
    </dependency>
    <dependency>
        <groupId>org.json</groupId>
        <artifactId>json</artifactId>
        <version>20141113</version>
    </dependency>
    <dependency>
        <groupId>commons-codec</groupId>
        <artifactId>commons-codec</artifactId>
        <version>1.10</version>
    </dependency>
</dependencies>

创建服务器

这段代码需要理解吗?这是 netty 的套路,可以先记住 netty 的线程模型是一个 react 的一种变型,这里有两个nio线程组,一个是接受客户端的请求,一个是worker组专门处理客户端的请求。

可以简单的理解下面的代码就构建了一个nginx服务器。所以不用管。

package net.mengkang;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;


public final class WebSocketServer {

    private static final int PORT = 8083;

    public static void main(String[] args) throws Exception {

        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new WebSocketServerInitializer());

            Channel ch = b.bind(PORT).sync().channel();
            ch.closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}
package net.mengkang;

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.extensions.compression.WebSocketServerCompressionHandler;


public class WebSocketServerInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    public void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast(new HttpServerCodec());
        pipeline.addLast(new HttpObjectAggregator(65536));
        pipeline.addLast(new WebSocketServerCompressionHandler());
        pipeline.addLast(new WebSocketServerHandler());
    }
}

处理长连接

下面程序中最的处理在握手阶段handleHttpRequest,里面处理参数的判断,用户的认证,登录用户表的维护,直播房间表维护。详细的请大家对照代码来浏览。
握手完成之后的消息传递则在handleWebSocketFrame中处理。
整理的执行流程,大家可以对各个方法打断点予以调试,就会很清楚整个执行的脉络啦。

package net.mengkang;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.*;
import io.netty.handler.codec.http.websocketx.*;
import io.netty.util.CharsetUtil;
import io.netty.util.concurrent.GlobalEventExecutor;
import net.mengkang.dto.Response;
import net.mengkang.entity.Client;
import net.mengkang.service.MessageService;
import net.mengkang.service.RequestService;
import org.json.JSONObject;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static io.netty.handler.codec.http.HttpHeaderNames.HOST;
import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpResponseStatus.*;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {

    // websocket 服务的 uri
    private static final String WEBSOCKET_PATH = "/websocket";

    // 一个 ChannelGroup 代表一个直播频道
    private static Map<Integer, ChannelGroup> channelGroupMap = new ConcurrentHashMap <>();

    // 本次请求的 code
    private static final String HTTP_REQUEST_STRING = "request";

    private Client client = null;

    private WebSocketServerHandshaker handshaker;

    @Override
    public void messageReceived(ChannelHandlerContext ctx, Object msg) {
        if (msg instanceof FullHttpRequest) {
            handleHttpRequest(ctx, (FullHttpRequest) msg);
        } else if (msg instanceof WebSocketFrame) {
            handleWebSocketFrame(ctx, (WebSocketFrame) msg);
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

    private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) {
        // Handle a bad request.
        if (!req.decoderResult().isSuccess()) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST));
            return;
        }

        // Allow only GET methods.
        if (req.method() != GET) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN));
            return;
        }

        if ("/favicon.ico".equals(req.uri()) || ("/".equals(req.uri()))) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, NOT_FOUND));
            return;
        }

        QueryStringDecoder queryStringDecoder = new QueryStringDecoder(req.uri());
        Map<String, List<String>> parameters = queryStringDecoder.parameters();

        if (parameters.size() == 0 || !parameters.containsKey(HTTP_REQUEST_STRING)) {
            System.err.printf(HTTP_REQUEST_STRING + "参数不可缺省");
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, NOT_FOUND));
            return;
        }

        client = RequestService.clientRegister(parameters.get(HTTP_REQUEST_STRING).get(0));
        if (client.getRoomId() == 0) {
            System.err.printf("房间号不可缺省");
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, NOT_FOUND));
            return;
        }

        // 房间列表中如果不存在则为该频道,则新增一个频道 ChannelGroup
        if (!channelGroupMap.containsKey(client.getRoomId())) {
            channelGroupMap.put(client.getRoomId(), new DefaultChannelGroup(GlobalEventExecutor.INSTANCE));
        }
        // 确定有房间号,才将客户端加入到频道中
        channelGroupMap.get(client.getRoomId()).add(ctx.channel());

        // Handshake
        WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(getWebSocketLocation(req), null, true);
        handshaker = wsFactory.newHandshaker(req);
        if (handshaker == null) {
            WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
        } else {
            ChannelFuture channelFuture = handshaker.handshake(ctx.channel(), req);

            // 握手成功之后,业务逻辑
            if (channelFuture.isSuccess()) {
                if (client.getId() == 0) {
                    System.out.println(ctx.channel() + " 游客");
                    return;
                }

            }
        }
    }

    private void broadcast(ChannelHandlerContext ctx, WebSocketFrame frame) {

        if (client.getId() == 0) {
            Response response = new Response(1001, "没登录不能聊天哦");
            String msg = new JSONObject(response).toString();
            ctx.channel().write(new TextWebSocketFrame(msg));
            return;
        }

        String request = ((TextWebSocketFrame) frame).text();
        System.out.println(" 收到 " + ctx.channel() + request);

        Response response = MessageService.sendMessage(client, request);
        String msg = new JSONObject(response).toString();
        if (channelGroupMap.containsKey(client.getRoomId())) {
            channelGroupMap.get(client.getRoomId()).writeAndFlush(new TextWebSocketFrame(msg));
        }

    }

    private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {

        if (frame instanceof CloseWebSocketFrame) {
            handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain());
            return;
        }
        if (frame instanceof PingWebSocketFrame) {
            ctx.channel().write(new PongWebSocketFrame(frame.content().retain()));
            return;
        }
        if (!(frame instanceof TextWebSocketFrame)) {
            throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass().getName()));
        }

        broadcast(ctx, frame);
    }

    private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) {
        if (res.status().code() != 200) {
            ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(), CharsetUtil.UTF_8);
            res.content().writeBytes(buf);
            buf.release();
            HttpHeaderUtil.setContentLength(res, res.content().readableBytes());
        }

        ChannelFuture f = ctx.channel().writeAndFlush(res);
        if (!HttpHeaderUtil.isKeepAlive(req) || res.status().code() != 200) {
            f.addListener(ChannelFutureListener.CLOSE);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel incoming = ctx.channel();
        System.out.println("收到" + incoming.remoteAddress() + " 握手请求");
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        if (client != null && channelGroupMap.containsKey(client.getRoomId())) {
            channelGroupMap.get(client.getRoomId()).remove(ctx.channel());
        }
    }

    private static String getWebSocketLocation(FullHttpRequest req) {
        String location = req.headers().get(HOST) + WEBSOCKET_PATH;
        return "ws://" + location;
    }
}

服务器端就写完啦,还有一些客户端对象的构想验证什么的就不一一细说了,都很简单,都在代码里。下面是客户端。

客户端程序

<html>
<head><title></title></head>
<body>
<script type="text/javascript">
var socket;
if (!window.WebSocket) {
  window.WebSocket = window.MozWebSocket;
}
if (window.WebSocket) {
  socket = new WebSocket("ws://localhost:8083/websocket/?request=e2lkOjE7cmlkOjI2O3Rva2VuOiI0MzYwNjgxMWM3MzA1Y2NjNmFiYjJiZTExNjU3OWJmZCJ9");
  socket.onmessage = function(event) {
      console.log(event.data);
  };
  socket.onopen = function(event) {
    console.log("websocket 打开了");
  };
  socket.onclose = function(event) {
    console.log("websocket 关闭了");
  };
}

function send(message) {
  if (!window.WebSocket) { return; }
  if (socket.readyState == WebSocket.OPEN) {
    socket.send(message);
  } else {
    alert("The socket is not open.");
  }
}
</script>
<form onsubmit="return false;">
  <input type="text" name="message" value="Hello, World!"/>
  <input type="button" value="Send Web Socket Data" onclick="send(this.form.message.value)" />
</form>
</body>
</html>

并发压测

同事 https://github.com/ideal 写的压测脚本
https://github.com/zhoumengka...
并测试为N个客户端,每个客户端发送10条消息,服务器配置2核4G内存,广播给所有的客户端,我们测试1500个并发的时候,负载在后期陡升。
实际情况下,不可能那么多人同时说话广播,而是说话的人少,接受广播的人多。

实际线上之后(业务远比上面的代码负载得多的多),在不限制刷帖频率大家狂轰滥炸的情况下,1500多人在线,半小时,负载一直都处于0.5以下。

最近老铁开了直播,欢迎来捧场!

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周梦康
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