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Netty断线重连

news 来源：原创 2024/5/5 17:26:06

Netty断线重连

最近使用Netty开发一个中转服务，需要一直保持与Server端的连接，网络中断后需要可以自动重连，查询官网资料，实现方案很简单，核心思想是在channelUnregistered钩子函数里执行重连。

创建连接

需要把configureBootstrap重构为一个函数，方便后续复用

      EventLoopGroup group = new NioEventLoopGroup(); 
        
private volatile Bootstrap bootstrap; 
        
public void init(String host, int port) throws RobotException { 
        
this.serverIp = host; 
        
this.serverPort = port; 
        
try { 
        
// 创建并初始化 Netty 客户端 Bootstrap 对象 
        
bootstrap = configureBootstrap(new Bootstrap(),group); 
        
bootstrap.option(ChannelOption.TCP_NODELAY, true); 
        
doConnect(bootstrap); 
        
} 
        
catch(Exception ex){ 
        
ex.printStackTrace(); 
        
throw new RobotException("connect remote control server error!",ex.getCause()); 
        
} 
        
} 
        
Bootstrap configureBootstrap(Bootstrap b, EventLoopGroup g) { 
        
b.group(g).channel(NioSocketChannel.class) 
        
.remoteAddress(serverIp, serverPort) 
        
.handler(new ChannelInitializer<SocketChannel>() { 
        
@Override 
        
public void initChannel(SocketChannel channel) throws Exception { 
        
ChannelPipeline pipeline = channel.pipeline(); 
        
// 编解码器 
        
pipeline.addLast(protoCodec); 
        
// 请求处理 
        
pipeline.addLast(RobotClient.this); 
        
} 
        
}); 
        
return b; 
        
} 
        
void doConnect(Bootstrap b) { 
        
try { 
        
ChannelFuture future = b.connect(); 
        
future.addListener(new ChannelFutureListener() { 
        
@Override 
        
public void operationComplete(ChannelFuture future) throws Exception { 
        
if (future.isSuccess()) { 
        
System.out.println("Started Tcp Client: " + serverIp); 
        
} else { 
        
System.out.println("Started Tcp Client Failed: "); 
        
} 
        
if (future.cause() != null) { 
        
future.cause().printStackTrace(); 
        
} 
        
} 
        
}); 
        
} catch (Exception e) { 
        
e.printStackTrace(); 
        
} 
        
}

断线重连

来看断线重连的关键代码：

      @ChannelHandler.Sharable 
        
public class RobotClient extends SimpleChannelInboundHandler<RobotProto> { 
        
@Override 
        
public void channelUnregistered(ChannelHandlerContext ctx) throws Exception { 
        
// 状态重置 
        
isConnected = false; 
        
this.serverStatus = -1; 
        
final EventLoop loop = ctx.channel().eventLoop(); 
        
loop.schedule(new Runnable() { 
        
@Override 
        
public void run() { 
        
doConnect(configureBootstrap(new Bootstrap(), loop)); 
        
} 
        
}, 1, TimeUnit.SECONDS); 
        
} 
        
}