在SpringBoot中整合使用Netty框架
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，那么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生命周期保持一致，同生共死
- 讓netty能用上ioc中的Bean
- 讓netty能讀取到全局的配置
整合Netty，提供WebSocket服務
這里演示一個案例，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，但這里用netty的實現 💖
添加依賴
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
</dependency>
是的，不用聲明版本號。因為 spring-boot-dependencies 中已經聲明了最新的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服務端口
port: 1024
# 綁定的網卡
ip: 0.0.0.0
# 消息幀最大體積
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。
在這里通過 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 接口。
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;
// 業務層處理數據
this.discardService.discard(textWebSocketFrame.text());
// 響應客戶端
ctx.channel().writeAndFlush(new TextWebSocketFrame("我收到了你的消息：" + System.currentTimeMillis()));
} else {
// 不接受文本以外的數據幀類型
ctx.channel().writeAndFlush(WebSocketCloseStatus.INVALID_MESSAGE_TYPE).addListener(ChannelFutureListener.CLOSE);
}
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
super.channelInactive(ctx);
LOGGER.info("鏈接斷開：{}", ctx.channel().remoteAddress());
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
super.channelActive(ctx);
LOGGER.info("鏈接創建：{}", 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，所有的鏈接都使用同一個hander，所以盡量不要保存任何實例變量。
這個Handler處理完畢客戶端的消息后，給客戶端會響應一條："我收到了你的消息：" + System.currentTimeMillis() 的消息
為了演示在Handler中使用業務層，這里假裝注入了一個 DiscardService 服務。它的邏輯很簡單，就是丟棄消息
public void discard (String message) {
LOGGER.info("丟棄消息:{}", 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('收到消息:', e.data);
}
websocket.onclose = e => {
let {code, reason} = e;
console.log(`鏈接斷開:code=${code}, reason=${reason}`);
}
websocket.onopen = () => {
console.log(`鏈接建立...`);
websocket.send('Hello');
}
websocket.onerror = e => {
console.log('鏈接異常:', e);
}
})();
</script>
</html>
鏈接創建后就給服務端發送一條消息：Hello
關閉服務端
使用 PostMan 請求服務器的停機端點
日志
客戶端日志
服務端日志
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 : 鏈接創建：/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 : 丟棄消息: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 : 鏈接斷開：/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啟動后啟動，App停止后關閉，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。