netty入门实例

TimeServer.java

package netty.timeserver.server;
 
import io.netty.bootstrap.ServerBootstrap;
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.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
 
public class TimeServer {
 
    public void bind(int port) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            // 配置服务器的NIO线程租
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childHandler(new ChildChannelHandler());
 
            // 绑定端口，同步等待成功
            ChannelFuture f = b.bind(port).sync();
            // 等待服务端监听端口关闭
            f.channel().closeFuture().sync();
        } finally {
            // 优雅退出，释放线程池资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
 
    private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {
        @Override
        protected void initChannel(SocketChannel arg0) throws Exception {
            System.out.println("server initChannel..");
            arg0.pipeline().addLast(new TimeServerHandler());
        }
    }
 
    public static void main(String[] args) throws Exception {
        int port = 9000;
        if (args != null && args.length > 0) {
            try {
                port = Integer.valueOf(args[0]);
            } catch (NumberFormatException e) {
 
            }
        }
 
        new TimeServer().bind(port);
    }
}

TimeServerHandler.java

package netty.timeserver.server;
 
import java.util.Date;
 
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
 
public class TimeServerHandler extends ChannelInboundHandlerAdapter {
 
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        System.out.println("server channelRead..");
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8");
        System.out.println("The time server receive order:" + body);
        String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new Date(
                System.currentTimeMillis()).toString() : "BAD ORDER";
        ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
        ctx.write(resp);
    }
 
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        System.out.println("server channelReadComplete..");
        ctx.flush();//刷新后才将数据发出到SocketChannel
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        System.out.println("server exceptionCaught..");
        ctx.close();
    }
 
}

TimeClient.java

package netty.timeserver.client;
 
import io.netty.bootstrap.Bootstrap;
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.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
 
public class TimeClient {
 
    public void connect(int port, String host) throws Exception {
        // 配置客户端NIO线程组
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group).channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel arg0)
                                throws Exception {
                            System.out.println("client initChannel..");
                            arg0.pipeline().addLast(new TimeClientHandler());
                        }
                    });
            // 发起异步连接操作
            ChannelFuture f = b.connect(host, port).sync();
            // 等待客户端链路关闭
            f.channel().closeFuture().sync();
        } finally {
            // 优雅退出，释放NIO线程组
            group.shutdownGracefully();
        }
    }
 
    public static void main(String[] args) throws Exception {
        int port = 9000;
        if (args != null && args.length > 0) {
            try {
                port = Integer.parseInt(args[0]);
            } catch (Exception e) {
            }
        }
        new TimeClient().connect(port, "127.0.0.1");
    }
}

TimeClientHandler.java

package netty.timeserver.client;
 
import java.util.logging.Logger;
 
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
 
public class TimeClientHandler extends ChannelInboundHandlerAdapter {
 
    private static final Logger logger = Logger
            .getLogger(TimeClientHandler.class.getName());
 
    private final ByteBuf firstMessage;
 
    public TimeClientHandler() {
        byte[] req = "QUERY TIME ORDER".getBytes();
        firstMessage = Unpooled.buffer(req.length);
        firstMessage.writeBytes(req);
    }
 
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        //与服务端建立连接后
        System.out.println("client channelActive..");
        ctx.writeAndFlush(firstMessage);
    }
 
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        System.out.println("client channelRead..");
        //服务端返回消息后
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8");
        System.out.println("Now is :" + body);
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        System.out.println("client exceptionCaught..");
        // 释放资源
        logger.warning("Unexpected exception from downstream:"
                + cause.getMessage());
        ctx.close();
    }
 
}