在SpringBoot中整合使用Netty框架的详细教程

在SpringBoot中整合使用Netty框架的详细教程

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

io.netty

netty-all

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:

endhttp://points:

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, 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() {

@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 , 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 {

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

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

日志

客户端日志

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'

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。

总结

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