在SpringBoot中整合使用Netty框架

灰太狼 2024-04-08 11:53 69阅读 0赞

Netty是一个非常优秀的Socket框架。如果需要在SpringBoot开发的app中，提供Socket服务，那么Netty是不错的选择。

Netty与SpringBoot的整合，我想无非就是要整合几个地方

*  让netty跟springboot生命周期保持一致，同生共死
 *  让netty能用上ioc中的Bean
 *  让netty能读取到全局的配置

### 整合Netty，提供WebSocket服务 ###

这里演示一个案例，在SpringBoot中使用Netty提供一个Websocket服务。

> servlet容器本身提供了websocket的实现，但这里用netty的实现 :sparkling\_heart:

#### 添加依赖 ####

<dependency>
    	<groupId>io.netty</groupId>
    	<artifactId>netty-all</artifactId>
    </dependency>

是的，不用声明版本号。因为 **spring-boot-dependencies** 中已经声明了最新的netty依赖。

#### 通过yaml配置基本的属性 ####

server:
      port: 80
    
    logging:
        level:
          root: DEBUG
    
    management:
      endpoints: 
        web:
          exposure:
            include: "*"
        
      endpoint:
        shutdown:
          enabled: true
    
    netty:
      websocket:
        # Websocket服务端口
        port: 1024
        # 绑定的网卡
        ip: 0.0.0.0
        # 消息帧最大体积
        max-frame-size: 10240
        # URI路径
        path: /channel

App使用了，**actuator**，并且开启暴露了 `shutdown` 端点，可以让SpringBoot App优雅的停机。 在这里通过 `netty.websocket.*` 配置 websocket服务相关的配置。

#### 通过 ApplicationRunner 启动Websocket服务 ####

import java.net.InetSocketAddress;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.boot.ApplicationArguments;
    import org.springframework.boot.ApplicationRunner;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.context.ApplicationListener;
    import org.springframework.context.event.ContextClosedEvent;
    import org.springframework.stereotype.Component;
    
    import io.netty.bootstrap.ServerBootstrap;
    import io.netty.channel.Channel;
    import io.netty.channel.ChannelFutureListener;
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.channel.ChannelInboundHandlerAdapter;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.ChannelPipeline;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.channel.socket.nio.NioServerSocketChannel;
    import io.netty.handler.codec.http.DefaultFullHttpResponse;
    import io.netty.handler.codec.http.FullHttpRequest;
    import io.netty.handler.codec.http.HttpObjectAggregator;
    import io.netty.handler.codec.http.HttpResponseStatus;
    import io.netty.handler.codec.http.HttpServerCodec;
    import io.netty.handler.codec.http.HttpVersion;
    import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
    import io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketServerCompressionHandler;
    import io.netty.handler.stream.ChunkedWriteHandler;
    import io.springboot.netty.websocket.handler.WebsocketMessageHandler;
    
    /**
     * 初始化Netty服务
     * @author Administrator
     */
    @Component
    public class NettyBootsrapRunner implements ApplicationRunner, ApplicationListener<ContextClosedEvent>, ApplicationContextAware {
    
    	private static final Logger LOGGER = LoggerFactory.getLogger(NettyBootsrapRunner.class);
    	
    	@Value("${netty.websocket.port}")
    	private int port;
    
    	@Value("${netty.websocket.ip}")
    	private String ip;
    	
    	@Value("${netty.websocket.path}")
    	private String path;
    	
    	@Value("${netty.websocket.max-frame-size}")
    	private long maxFrameSize;
    	
    	private ApplicationContext applicationContext;
    	
    	private Channel serverChannel;
    	
    	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    		this.applicationContext = applicationContext;
    	}
    	
    	public void run(ApplicationArguments args) throws Exception {
    		
    		EventLoopGroup bossGroup = new NioEventLoopGroup();
    		EventLoopGroup workerGroup = new NioEventLoopGroup();
    		try {
    			ServerBootstrap serverBootstrap = new ServerBootstrap();
    			serverBootstrap.group(bossGroup, workerGroup);
    			serverBootstrap.channel(NioServerSocketChannel.class);
    			serverBootstrap.localAddress(new InetSocketAddress(this.ip, this.port));
    			serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
    				@Override
    				protected void initChannel(SocketChannel socketChannel) throws Exception {
    					ChannelPipeline pipeline = socketChannel.pipeline();
    					pipeline.addLast(new HttpServerCodec());
    					pipeline.addLast(new ChunkedWriteHandler());
    					pipeline.addLast(new HttpObjectAggregator(65536));
    					pipeline.addLast(new ChannelInboundHandlerAdapter() {
    						@Override
    						public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    							if(msg instanceof FullHttpRequest) {
    								FullHttpRequest fullHttpRequest = (FullHttpRequest) msg;
    								String uri = fullHttpRequest.uri();
    								if (!uri.equals(path)) {
    									// 访问的路径不是 websocket的端点地址，响应404
    									ctx.channel().writeAndFlush(new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.NOT_FOUND))
    										.addListener(ChannelFutureListener.CLOSE);
    									return ;
    								}
    							}
    							super.channelRead(ctx, msg);
    						}
    					});
    					pipeline.addLast(new WebSocketServerCompressionHandler());
    					pipeline.addLast(new WebSocketServerProtocolHandler(path, null, true, maxFrameSize));
    
    					/**
    					 * 从IOC中获取到Handler
    					 */
    					pipeline.addLast(applicationContext.getBean(WebsocketMessageHandler.class));
    				}
    			});
    			Channel channel = serverBootstrap.bind().sync().channel();	
    			this.serverChannel = channel;
    			LOGGER.info("websocket 服务启动，ip={},port={}", this.ip, this.port);
    			channel.closeFuture().sync();
    		} finally {
    			bossGroup.shutdownGracefully();
    			workerGroup.shutdownGracefully();
    		}
    	}
    
    	public void onApplicationEvent(ContextClosedEvent event) {
    		if (this.serverChannel != null) {
    			this.serverChannel.close();
    		}
    		LOGGER.info("websocket 服务停止");
    	}
    }

`NettyBootsrapRunner` 实现了 ApplicationRunner, `ApplicationListener<ContextClosedEvent>`, `ApplicationContextAware` 接口。

这样一来，`NettyBootsrapRunner` 可以在App的启动和关闭时执行Websocket服务的启动和关闭。而且通过 `ApplicationContextAware` 还能获取到 `ApplicationContext`

#### 通过IOC管理 Netty 的Handler ####

import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Component;
    
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.channel.SimpleChannelInboundHandler;
    import io.netty.channel.ChannelFutureListener;
    import io.netty.channel.ChannelHandler.Sharable;
    import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
    import io.netty.handler.codec.http.websocketx.WebSocketCloseStatus;
    import io.netty.handler.codec.http.websocketx.WebSocketFrame;
    import io.springboot.netty.service.DiscardService;
    /**
     * 
     * @author Administrator
     *
     */
    @Sharable
    @Component
    public class WebsocketMessageHandler extends SimpleChannelInboundHandler<WebSocketFrame> {
    	
    	private static final Logger LOGGER = LoggerFactory.getLogger(WebsocketMessageHandler.class);
    	
    	@Autowired
    	DiscardService discardService;
    	
    	@Override
    	protected void channelRead0(ChannelHandlerContext ctx, WebSocketFrame msg) throws Exception {
    		if (msg instanceof TextWebSocketFrame) {
    			TextWebSocketFrame textWebSocketFrame = (TextWebSocketFrame) msg;
    			// 业务层处理数据
    			this.discardService.discard(textWebSocketFrame.text());
    			// 响应客户端
    			ctx.channel().writeAndFlush(new TextWebSocketFrame("我收到了你的消息：" + System.currentTimeMillis()));
    		} else {
    			// 不接受文本以外的数据帧类型
    			ctx.channel().writeAndFlush(WebSocketCloseStatus.INVALID_MESSAGE_TYPE).addListener(ChannelFutureListener.CLOSE);
    		}
    	}
    	
    	@Override
    	public void channelInactive(ChannelHandlerContext ctx) throws Exception {
    		super.channelInactive(ctx);
    		LOGGER.info("链接断开：{}", ctx.channel().remoteAddress());
    	}
    	@Override
    	public void channelActive(ChannelHandlerContext ctx) throws Exception {
    		super.channelActive(ctx);
    		LOGGER.info("链接创建：{}", ctx.channel().remoteAddress());
    	}
    }

handler已经是一个IOC管理的Bean，可以自由的使用依赖注入等Spring带来的快捷功能。由于是单例存在，所有的链接都使用同一个hander，所以尽量不要保存任何实例变量。

这个Handler处理完毕客户端的消息后，给客户端会响应一条：`"我收到了你的消息：" + System.currentTimeMillis()` 的消息

为了演示在Handler中使用业务层，这里假装注入了一个 `DiscardService`服务。它的逻辑很简单，就是丢弃消息

public void discard (String message) {
    	LOGGER.info("丢弃消息:{}", message);
    }

### 演示 ###

#### 启动客户端 ####

<!DOCTYPE html>
    	<html>
    	<head>
    		<meta charset="UTF-8">
    		<title>Websocket</title>
    	</head>
    	<body>
    	
    	</body>
    	<script type="text/javascript">
    		;(function(){
    			const websocket = new WebSocket('ws://localhost:1024/channel');
    			websocket.onmessage = e => {
    				console.log('收到消息:', e.data);
    			}
    			websocket.onclose = e => {
    				let {code, reason} = e;
    				console.log(`链接断开:code=${code}, reason=${reason}`);
    			}
    			websocket.onopen = () => {
    				console.log(`链接建立...`);
    				websocket.send('Hello');
    			}
    			websocket.onerror = e => {
    				console.log('链接异常:', e);
    			}
    		})();
    
    	</script>
    </html>

链接创建后就给服务端发送一条消息：`Hello`

#### 关闭服务端 ####

使用 PostMan 请求服务器的停机端点

![585b74d93a474341aac9b9bc8ebd8f24.jpeg][]

#### 日志 ####

客户端日志

![5b53ae9eee9649bf8a5081d1604187b1.png][]

服务端日志

2020-06-22 17:08:22.728  INFO 9392 --- [           main] io.undertow                              : starting server: Undertow - 2.1.3.Final
    2020-06-22 17:08:22.740  INFO 9392 --- [           main] org.xnio                                 : XNIO version 3.8.0.Final
    2020-06-22 17:08:22.752  INFO 9392 --- [           main] org.xnio.nio                             : XNIO NIO Implementation Version 3.8.0.Final
    2020-06-22 17:08:22.839  INFO 9392 --- [           main] org.jboss.threads                        : JBoss Threads version 3.1.0.Final
    2020-06-22 17:08:22.913  INFO 9392 --- [           main] o.s.b.w.e.undertow.UndertowWebServer     : Undertow started on port(s) 80 (http)
    2020-06-22 17:08:22.931  INFO 9392 --- [           main] io.springboot.netty.NettyApplication     : Started NettyApplication in 4.536 seconds (JVM running for 5.175)
    2020-06-22 17:08:23.653  INFO 9392 --- [           main] i.s.n.w.runner.NettyBootsrapRunner       : websocket 服务启动，ip=0.0.0.0,port=1024
    2020-06-22 17:08:28.484  INFO 9392 --- [  XNIO-1 task-1] io.undertow.servlet                      : Initializing Spring DispatcherServlet 'dispatcherServlet'
    2020-06-22 17:08:28.484  INFO 9392 --- [  XNIO-1 task-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2020-06-22 17:08:28.492  INFO 9392 --- [  XNIO-1 task-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 8 ms
    2020-06-22 17:08:28.724  INFO 9392 --- [ntLoopGroup-3-1] i.s.n.w.handler.WebsocketMessageHandler  : 链接创建：/0:0:0:0:0:0:0:1:12093
    2020-06-22 17:08:28.790  INFO 9392 --- [ntLoopGroup-3-1] i.s.netty.service.DiscardService         : 丢弃消息:Hello
    2020-06-22 17:08:33.688  INFO 9392 --- [     Thread-232] i.s.n.w.runner.NettyBootsrapRunner       : websocket 服务停止
    2020-06-22 17:08:33.691  INFO 9392 --- [ntLoopGroup-3-1] i.s.n.w.handler.WebsocketMessageHandler  : 链接断开：/0:0:0:0:0:0:0:1:12093
    2020-06-22 17:08:33.699  INFO 9392 --- [     Thread-232] io.undertow                              : stopping server: Undertow - 2.1.3.Final
    2020-06-22 17:08:33.704  INFO 9392 --- [     Thread-232] io.undertow.servlet                      : Destroying Spring FrameworkServlet 'dispatcherServlet'
    2020-06-22 17:08:33.708  INFO 9392 --- [     Thread-232] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'
    复制代码

Netty会在SpringBoot App启动后启动，App停止后关闭，可以正常的对外提供服务 并且Handler交给IOC管理可以注入Service，完成业务处理。

[585b74d93a474341aac9b9bc8ebd8f24.jpeg]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/08/2eb418c521754a149278012666617d21.jpeg
[5b53ae9eee9649bf8a5081d1604187b1.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/08/54847110737048d8930c52358b59f46e.png