netty websockt之断连重试

断连重试有以下两点考虑：

1、连接异常，比如网络抖动导致连接失败；

2、连接过程中断开连接重试；

主要用到两个工具类：

ChannelFutureListener监听ChannelFuture..isSuccess()；

ChannelInboundHandlerAdapter重写channelInactive，当连接变为不活跃，则回调该方法。

完整代码如下：

@Component
public class WebSocketClient {private Channel channel;private Bootstrap bootstrap;private URI uri;private MessageHandler messageHandler;private WebSocketClientHandler handler;private volatile AtomicInteger atomicCount = new AtomicInteger(0);public WebSocketClient initClient(String host, MessageHandler messageHandler) throws Exception {this.messageHandler = messageHandler;if (StringUtils.isEmpty(host)) {throw new RuntimeException("未配置host.");}uri = new URI(host);String scheme = uri.getScheme() == null? WssSchemeEnum.WS.getValue() : uri.getScheme();//判断是否ssl连接，如果是则设置为可信final boolean ssl = WssSchemeEnum.WSS.getValue().equalsIgnoreCase(scheme);final SslContext sslCtx;if (ssl) {sslCtx = SslContextBuilder.forClient().trustManager(InsecureTrustManagerFactory.INSTANCE).build();} else {sslCtx = null;}EventLoopGroup group = new NioEventLoopGroup();try {bootstrap = new Bootstrap();bootstrap.group(group).channel(NioSocketChannel.class).handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) {ChannelPipeline p = ch.pipeline();p.addFirst(new ChannelInboundHandlerAdapter() {@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {log.error("【{}】检测到wss断连, 第 {} 次发起重连.", exchange, atomicCount.incrementAndGet());super.channelInactive(ctx);ctx.channel().eventLoop().schedule(WebSocketClient.this::doConnect, 3000, TimeUnit.MILLISECONDS);}});if (sslCtx != null) {p.addLast(sslCtx.newHandler(ch.alloc(), uri.getHost(), getUriPort(uri)));}p.addLast(new HttpClientCodec());p.addLast(new HttpObjectAggregator(8192));p.addLast(WebSocketClientCompressionHandler.INSTANCE);handler = new WebSocketClientHandler(WebSocketClientHandshakerFactory.newHandshaker(uri, WebSocketVersion.V13, null, true, new DefaultHttpHeaders()), exchange, messageHandler);p.addLast(handler);}});} catch (Exception e) {log.error("wss创建client异常. e:", e);if (bootstrap != null) {bootstrap.config().group().shutdownGracefully();}throw new RuntimeException("初始化wss连接异常. e: " + e);}doConnect();return this;}public void doConnect() {try {ChannelFuture future = bootstrap.connect(uri.getHost(), getUriPort(uri)).sync();handler.handshakeFuture().sync();future.addListener((ChannelFutureListener) cf -> {if (future.isSuccess()) {channel = future.channel();WssManger.addChannel(exchange, channel);log.info("连接成功.");messageHandler.connectSuccessAction(future.channel());atomicCount.set(0);} else {log.error("监听断连, wss第 {} 次发起重连. ", atomicCount.incrementAndGet());future.channel().eventLoop().schedule(WebSocketClient.this::doConnect, 3000, TimeUnit.MILLISECONDS);}});}catch (Exception e) {log.error("连接异常. e:" + e);if (bootstrap != null) {log.info("wss连接异常，第 {} 次发起重连.", atomicCount.incrementAndGet());bootstrap.config().group().schedule(WebSocketClient.this::doConnect, 3000, TimeUnit.MILLISECONDS);}}}/*** 根据URI获取对应的port** @param uri uri* @return port*/private int getUriPort(URI uri) {String scheme = uri.getScheme() == null? WssSchemeEnum.WS.getValue() : uri.getScheme();if (!WssSchemeEnum.allScheme().contains(scheme)) {throw new RuntimeException("Only WS(S) is supported.");}if (uri.getPort() == -1) {if (WssSchemeEnum.WS.getValue().equalsIgnoreCase(scheme)) {return WssSchemeEnum.WS.getPort();} else if (WssSchemeEnum.WSS.getValue().equalsIgnoreCase(scheme)) {return WssSchemeEnum.WSS.getPort();} else {return -1;}} else {return uri.getPort();}}
}