在SpringBoot中整合使用Netty框架的詳細教程
Netty是一個非常優秀的Socket框架。如果需要在SpringBoot開發的app中，提供Socket服務，那麼Netty是不錯的選擇。
Netty與SpringBoot的整合，我想無非就是要整合幾個地方
- 讓netty跟springboot生命週期保持一致，同生共死
- 讓netty能用上ioc中的Bean
- 讓netty能讀取到全域性的配置
整合Netty，提供WebSocket服務
這裡演示一個案例，在SpringBoot中使用Netty提供一個Websocket服務。
servlet容器本身提供了websocket的實現，但這裡用netty的實現 :sparkling_heart:
新增依賴
<dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> </dependency>
是的，不用宣告版本號。因為 spring-boot-dependencies 中已經聲明瞭最新的netty依賴。
通過yaml配置基本的屬性
server: port: 80 logging: level: root: DEBUG management: endpoints: web: exposure: include: "*" endpoint: shutdown: enabled: true netty: websocket: # Websocket服務埠 port: 1024 # 繫結的網絡卡 ip: 0.0.0.0 # 訊息幀最大體積 max-frame-size: 10240 # URI路徑 path: /channel
App使用了， actuator ，並且開啟暴露了 shutdown 端點，可以讓SpringBoot App優雅的停機。 在這裡通過 netty.websocket.* 配置 websocket服務相關的配置。
通過 ApplicationRunner 啟動Websocket服務
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服務
* @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)) {
// 訪問的路徑不是 websocket的端點地址，響應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));
/**
* 從IOC中獲取到Handler
*/
pipeline.addLast(applicationContext.getBean(WebsocketMessageHandler.class));
}
});
Channel channel = serverBootstrap.bind().sync().channel();
this.serverChannel = channel;
LOGGER.info("websocket 服務啟動，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 服務停止");
}
}NettyBootsrapRunner 實現了 ApplicationRunner,ApplicationListener<ContextClosedEvent>,ApplicationContextAware 介面。
這樣一來， NettyBootsrapRunner 可以在App的啟動和關閉時執行Websocket服務的啟動和關閉。而且通過 ApplicationContextAware 還能獲取到 ApplicationContext
通過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;
// 業務層處理資料
this.discardService.discard(textWebSocketFrame.text());
// 響應客戶端
ctx.channel().writeAndFlush(new TextWebSocketFrame("我收到了你的訊息：" + System.currentTimeMillis()));
} else {
// 不接受文字以外的資料幀型別
ctx.channel().writeAndFlush(WebSocketCloseStatus.INVALID_MESSAGE_TYPE).addListener(ChannelFutureListener.CLOSE);
}
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
super.channelInactive(ctx);
LOGGER.info("連結斷開：{}",ctx.channel().remoteAddress());
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
super.channelActive(ctx);
LOGGER.info("連結建立：{}",ctx.channel().remoteAddress());
}
}
handler已經是一個IOC管理的Bean，可以自由的使用依賴注入等Spring帶來的快捷功能。由於是單例存在，所有的連結都使用同一個hander，所以儘量不要儲存任何例項變數。
這個Handler處理完畢客戶端的訊息後，給客戶端會響應一條： "我收到了你的訊息：" + System.currentTimeMillis() 的訊息
為了演示在Handler中使用業務層，這裡假裝注入了一個 DiscardService 服務。它的邏輯很簡單，就是丟棄訊息
public void discard (String message) {
LOGGER.info("丟棄訊息:{}",message);
}
演示
啟動客戶端
<!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('收到訊息:',e.data);
}
websocket.onclose = e => {
let {code,reason} = e;
console.log(`連結斷開:code=$[code],reason=${reason}`);
}
websocket.onopen = () => {
console.log(`連結建立...`);
websocket.send('Hello');
}
websocket.onerror = e => {
console.log('連結異常:',e);
}
})();
</script>
</html>
連結建立後就給服務端傳送一條訊息： Hello
關閉服務端
使用 PostMan 請求伺服器的停機端點
日誌
客戶端日誌
服務端日誌
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 服務啟動，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 : 連結建立：/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 : 丟棄訊息:Hello
2020-06-22 17:08:33.688 INFO 9392 --- [ Thread-232] i.s.n.w.runner.NettyBootsrapRunner : websocket 服務停止
2020-06-22 17:08:33.691 INFO 9392 --- [ntLoopGroup-3-1] i.s.n.w.handler.WebsocketMessageHandler : 連結斷開：/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會在SpringBoot App啟動後啟動，App停止後關閉，可以正常的對外提供服務 並且Handler交給IOC管理可以注入Service，完成業務處理。
總結
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