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();  
privatevolatile 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();  
thrownew 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  
publicclass 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);  
}  
}  