introducción
Estuve viendo "Netty en acción" recientemente, y uno de los casos es una implementación de cliente/servidor de eco. Este solía ser un caso clásico cuando se usaba jdk nativo.
Pero la única diferencia es que anteriormente la entrada se leía desde la consola.
Este es un caso de lectura de entrada desde la consola.
Servidor
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import java.net.InetSocketAddress;
import java.nio.charset.StandardCharsets;
public class Server {
private static final int port = 10086;
public static void main(String[] args) throws InterruptedException {
ServerBootstrap bootstrap = new ServerBootstrap();
NioEventLoopGroup group = new NioEventLoopGroup();
try {
bootstrap.group(group)
.channel(NioServerSocketChannel.class)
.localAddress(new InetSocketAddress(port))
.childHandler(new ChannelInitializer<>() {
@Override
protected void initChannel(Channel ch) throws Exception {
ch.pipeline().addLast(new SimpleChannelInboundHandler<ByteBuf>() {
@Override
protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
String string = msg.toString(StandardCharsets.UTF_8);
System.out.println("server received: " + string);
ctx.write(msg);
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("client: " + ctx.channel().remoteAddress() + " active!");
super.channelActive(ctx);
}
@Override
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("client: " + ctx.channel().remoteAddress() + " register!");
super.channelRegistered(ctx);
}
@Override
public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("client: " + ctx.channel().remoteAddress() + " unregister!");
super.channelUnregistered(ctx);
}
});
}
});
ChannelFuture future = bootstrap.bind().sync();
future.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
group.shutdownGracefully().sync();
}
}
}
cliente
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.nio.charset.StandardCharsets;
public class Client {
private static String host = "127.0.0.1";
private static int port = 10086;
public static void main(String[] args) throws InterruptedException {
NioEventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group)
.channel(NioSocketChannel.class)
.remoteAddress(new InetSocketAddress(host, port))
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new SimpleChannelInboundHandler<ByteBuf>() {
@Override
protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
System.out.println("Client received: " + msg.toString(StandardCharsets.UTF_8));
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("channel active!");
ctx.writeAndFlush(Unpooled.copiedBuffer("hello server!", StandardCharsets.UTF_8));
}
});
}
});
ChannelFuture future = bootstrap.connect().sync();
Channel channel = future.channel();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
String line;
while (!"over".equals(line = bufferedReader.readLine())) {
System.out.println(line);
channel.writeAndFlush(Unpooled.copiedBuffer(line, StandardCharsets.UTF_9));
}
} catch (IOException e) {
e.printStackTrace();
} finally {
group.shutdownGracefully().sync();
}
}
}
correr
Inicie el servidor primero, luego inicie el cliente.
El cliente primero generará:
channel active!
Entonces el servidor emite:
client: /127.0.0.1:62414 register!
client: /127.0.0.1:62414 active!
server received: hello server!
Luego cambie a la consola del cliente:
puede ver la salida del servidor:
