netty笔记(一)--Demo

Netty是一个Java开源框架，用于传输数据。由server和client组成，封装了Java nio，支持TCP, UDP等协议。这里写了一Demo

EchoClientHandler.java

package chapter1;
 
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;
 
@ChannelHandler.Sharable
public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> {
 
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush(Unpooled.copiedBuffer("hello guanxianseng", CharsetUtil.UTF_8));
    }
 
    protected void messageReceived(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
        System.out.println("Client received:" + msg.toString(CharsetUtil.UTF_8));
        System.out.println(msg.toString());
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
 
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Client received:" + msg.toString());
 
    }
}

EchoServer.java

package chapter1;
 
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
 
import java.net.InetSocketAddress;
import java.util.concurrent.TimeUnit;
 
public class EchoServer {
    private  int port = 1234;
 
    public EchoServer(int port) {
        this.port = port;
    }
 
    public static void main(String[] args) throws Exception{
        int port = 1234;
        EchoServer echoServer = new EchoServer(port);
        schedulTask();
        echoServer.start();
 
    }
 
    public void start() throws Exception{
        final EchoServerHandler serverHandler = new EchoServerHandler();
        EventLoopGroup group = new NioEventLoopGroup();
        try{
            ServerBootstrap b = new ServerBootstrap();
            b.group(group)
                    .channel(NioServerSocketChannel.class)
                    .localAddress(new InetSocketAddress(port))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(serverHandler);
                        }
                    });
            ChannelFuture channelFuture = b.bind().sync();
            System.out.println("sync test1");
            channelFuture.channel().closeFuture().sync();
            System.out.println("sync test2");
 
        } catch (Exception e){
 
        }finally {
            group.shutdownGracefully().sync();
            System.out.println("sync test3");
        }
    }
 
    public static void schedulTask(){
        System.out.println("before test");
        Channel ch = new EmbeddedChannel();
        ch.eventLoop().scheduleAtFixedRate(new Runnable() {
            public void run() {
                System.out.println("test");
            }
        }, 0, 5, TimeUnit.SECONDS);
    }
}

EchoClientHandler.java

package chapter1;
 
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;
 
@ChannelHandler.Sharable
public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> {
 
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush(Unpooled.copiedBuffer("hello guanxianseng", CharsetUtil.UTF_8));
    }
 
    protected void messageReceived(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
        System.out.println("Client received:" + msg.toString(CharsetUtil.UTF_8));
        System.out.println(msg.toString());
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
 
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Client received:" + msg.toString());
 
    }
}

EchoClient.java

package chapter1;
 
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
 
import java.net.InetSocketAddress;
 
public class EchoClient {
    private String host;
    private int port;
 
    public EchoClient(String host, int port) {
        this.host = host;
        this.port = port;
    }
 
    public static void main(String[] args) throws Exception {
        int port = 1234;
        String host = "127.0.0.1";
        EchoClient echoClient = new EchoClient(host, port);
        echoClient.start();
    }
 
    public void start() throws Exception{
        EventLoopGroup group = new NioEventLoopGroup();
        try{
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .remoteAddress(new InetSocketAddress(host, port))
                    .handler(new ChannelInitializer<SocketChannel>() {
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new EchoClientHandler());
                        }
                    });
            ChannelFuture f = b.connect().sync();
            f.channel().closeFuture().sync();
 
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            group.shutdownGracefully().sync();
        }
    }
}

netty如何实现各种回调，怎么发送、接收消息，还要看下源码