Netty 的 Hello World 案例分成两部分。一部分是服务端，将接收到的消息打印出来即可。另外一部分是客户端，发送消息。
服务端
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| public class Server {
public static void main(String[] args) {
EventLoopGroup boss = new NioEventLoopGroup();
EventLoopGroup worker = new NioEventLoopGroup();
try {
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(boss, worker)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<NioSocketChannel>() {
@Override
protected void initChannel(NioSocketChannel nioSocketChannel) throws Exception {
nioSocketChannel.pipeline()
.addLast(new StringDecoder())
.addLast(new SimpleChannelInboundHandler<String>() {
@Override
protected void channelRead0(ChannelHandlerContext channelHandlerContext, String s) throws Exception {
System.out.println("server 接收到的消息" + s);
}
});
}
});
ChannelFuture channelFuture = serverBootstrap.bind("localhost", 8888);
channelFuture.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
worker.shutdownGracefully();
boss.shutdownGracefully();
}
}
}
|
EventLoopGroup
- 创建了两个反应器线程组，分别为
boss 和 worker ，boss 接收到请求后交由 worker 处理。
ServerBootstrap
- 服务端引导器，服务端引导器主要是为了进行一些配置，主要有以下配置。
- group 配置线程组
- channel 配置通道类型
- childHandler 配置一些 Handler
- 绑定的地址和端口
客户端
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| public class Client {
public static void main(String[] args) {
EventLoopGroup worker = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
try {
bootstrap.group(worker)
.channel(NioSocketChannel.class)
.option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
socketChannel.pipeline().addLast(new StringEncoder());
}
});
ChannelFuture channelFuture = bootstrap.connect("localhost", 8888);
Channel channel = channelFuture.channel();
while (true) {
String msg = LocalDateTime.now().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) + ": Hello world!!!";
channel.writeAndFlush(msg);
TimeUnit.SECONDS.sleep(2);
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
worker.shutdownGracefully();
}
}
}
|
NioEventLoopGroup
- 在客户端，只有
worker 线程组，没有 boss ，只需要配置一个 worker 即可。
其余与 服务端 大致类似。
最终效果，客户端控制台无任何输出。服务端控制台，每隔两秒钟就会打印当前时间 + Hello Wold 的字样。