Netty客户端连接服务端失败及断开与客户端连接时尝试重连

Netty客户端重连机制

场景：
1.Netty初次启动客户端，如果无法连接到服务端，将尝试重连。
2.在客户端与服务端保持长连接的过程中，如果连接断开，尝试与服务端重连。

主要代码

Netty客户端启动处理类

@Service("nettyClient")
public class NettyClient {
	private final static Logger log = LoggerFactory.getLogger(NettyClient.class);
	private EventLoopGroup loop = new NioEventLoopGroup();

	@Autowired
	private NettyFilter nettyFilter;

	@Autowired
	private AppConfig appConfig;

	/**
	 * 重连标志
	 */
	public static boolean retryConnectFlag = false;

	public void run() {

		doConnect(new Bootstrap(), loop);
	}

	/**
	 * netty client 连接，连接失败10秒后重试连接
	 */
	public void doConnect(Bootstrap bootstrap, EventLoopGroup eventLoopGroup) {
		ChannelFuture f = null;
		try {
			if (bootstrap != null) {
				bootstrap.group(eventLoopGroup);
				bootstrap.channel(NioSocketChannel.class);
				bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
				bootstrap.handler(nettyFilter);
				bootstrap.remoteAddress(appConfig.getHost(), appConfig.getPort());
				bootstrap.connect().addListener(new ChannelFutureListener() {
					
					@Override
					public void operationComplete(ChannelFuture future) throws Exception {
						// TODO Auto-generated method stub
						
					}
				});
				// 	Cache.channel为缓存的与服务端的连接channel,在其他发送消息的时候使用。
				Cache.channel = bootstrap.connect().addListener((ChannelFuture futureListener) -> {
					final EventLoop eventLoop = futureListener.channel().eventLoop();
					if (!futureListener.isSuccess()) {
						log.warn("客户端与服务端建立连接失败，10s之后尝试重连...");
						eventLoop.schedule(() -> doConnect(new Bootstrap(), eventLoop), 10, TimeUnit.SECONDS);
					} else {
						if (retryConnectFlag) {
							// 如果连接成功后，再次断开，则尝试重连。
							retryConnectFlag = false;
							log.info("客户端重连成功，port：{}", appConfig.getPort());
						} else {
						   // 客户端首次成功连接服务端后，这里有个验证登录服务端的动作（不要验证可以取消）
							log.info("客户端与服务器连接成功，port：{}，开始登录服务端...", appConfig.getPort());
						}
					}
				}).channel();
			}
		} catch (Exception e) {
			log.error("连接客户端失败,失败信息：" + e);
		}finally {
			// 要实现重连，所以不能关闭loop
			//loop.shutdownGracefully();
		}
	}
}

客户端与服务端心跳处理类，与客户端断开连接后的重试代码在channelInactive()这个方法中

@Service("idleclienthandler")
@ChannelHandler.Sharable
public class IdleClientHandler extends SimpleChannelInboundHandler<MessageBase> {
	private final static Logger logger = LoggerFactory.getLogger(IdleClientHandler.class);
	private long heartbeatCount = 0;
	
	@Autowired
	private NettyClient nettyClient;


	@Override
	public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
		if (evt instanceof IdleStateEvent) {
			IdleStateEvent event = (IdleStateEvent) evt;
		 	logger.info(ctx.channel().remoteAddress() + "，超时类型：" + event.state());
			sendPingMsg(ctx);
		} else {
			super.userEventTriggered(ctx, evt);
		}
	}

	/**
	 * 发送ping消息
	 * @param context
	 */
	protected void sendPingMsg(ChannelHandlerContext context) {
		MessageBase body = NettyMessage.MessageBase.newBuilder()
				.setCmd(CommandType.PING)
				.setPtcode(Cache.ptcode)
				.setData("ping")
				.build();
		context.writeAndFlush(body);
		heartbeatCount++;
		logger.info("Client sent ping msg to " + context.channel().remoteAddress() + ", count: " + heartbeatCount);
	}

	/**
	 * 处理断开重连
	 */
	@SuppressWarnings("static-access")
	@Override
	public void channelInactive(ChannelHandlerContext ctx) throws Exception {
		logger.info("与服务器连接断开，尝试重新连接...");
		nettyClient.retryConnectFlag = true;
		final EventLoop eventLoop = ctx.channel().eventLoop();  
	    nettyClient.doConnect(new Bootstrap(), eventLoop);  
		super.channelInactive(ctx);  
	}

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, MessageBase msg) throws Exception {
		logger.info("收到的消息!{}",msg);
	}
}

Netty客户端连接服务端失败及断开与客户端连接时尝试重连

Netty客户端重连机制

猜你喜欢