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~