netty4简易教程

近来有空，研究了一下netty。netty5还只是beta版本，官方建议使用netty4。

这个实例中，Client通过控制台输入信息，与Server端通信。

对于普通开发者来说，netty4的常用接口有：SimpleChannelInboundHandler/SimpleChannelOutboundHandler、ChannelInitializer、encoder和decoder相关的类。

服务器端：

1、编写handler类

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class ServerHandler extends SimpleChannelInboundHandler {
@Override
public void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("server:" + "channelRead:" + msg);
ctx.writeAndFlush("Received your message !");
}
}

2、注册服务，绑定端口：

import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.protobuf.ProtobufDecoder;
import io.netty.handler.codec.protobuf.ProtobufEncoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class Server {


public static void main(String[] args) {
EventLoopGroup bossEventLoopGroup = new NioEventLoopGroup();
EventLoopGroup workerEventLoopGroup = new NioEventLoopGroup();
try {
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossEventLoopGroup, workerEventLoopGroup);
serverBootstrap.channel(NioServerSocketChannel.class);
serverBootstrap.childHandler(new ChannelInitializer<Channel>() {
@Override
protected void initChannel(Channel ch) throws Exception {
ch.pipeline().addLast("encoder", new StringEncoder());
ch.pipeline().addLast("decoder", new StringDecoder());
ch.pipeline().addLast("handler", new ServerHandler());
};
});
serverBootstrap.childOption(ChannelOption.SO_KEEPALIVE, true);
ChannelFuture channelFuture = serverBootstrap.bind(8888).sync();
channelFuture.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
bossEventLoopGroup.shutdownGracefully();
workerEventLoopGroup.shutdownGracefully();
}
}
}

客户端：

1、编写handler类

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class ClientHandler extends SimpleChannelInboundHandler {

@Override
protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("client:" + "channelRead:" + msg);
}
}

2、编写请求入口

import java.io.BufferedReader;
import java.io.InputStreamReader;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.protobuf.ProtobufDecoder;
import io.netty.handler.codec.protobuf.ProtobufEncoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class Client {

public static void main(String[] args) {
EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(eventLoopGroup);
bootstrap.channel(NioSocketChannel.class);
bootstrap.handler(new ChannelInitializer<Channel>() {
@Override
protected void initChannel(Channel ch) throws Exception {
ch.pipeline().addLast("encoder", new StringEncoder());
ch.pipeline().addLast("decoder", new StringDecoder());
ch.pipeline().addLast("handler", new ClientHandler());
};
});

Channel ch = bootstrap.connect("127.0.0.1", 8888).sync().channel();

// 控制台输入
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
for (;;) {
String line = in.readLine();
if (line == null || "".equals(line)) {
continue;
}
ch.writeAndFlush(line);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
eventLoopGroup.shutdownGracefully();
}
}
}

入门教程，欢迎拍砖~