搭建第一个netty程序

来自action In netty 自己修改一点点 

主要依赖

     <dependencies>
            <dependency>
                <groupId>io.netty</groupId>
                <artifactId>netty-all</artifactId>
                <version>${netty.version}</version>
            </dependency>
            <dependency>
                <groupId>nia</groupId>
                <artifactId>utils</artifactId>
                <version>2.0-SNAPSHOT</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>${junit.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
        </dependency>
        <dependency>
            <groupId>nia</groupId>
            <artifactId>utils</artifactId>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
    </dependencies>

server端代码

package nia.chapter2.echoserver;

import java.net.InetSocketAddress;

import io.netty.bootstrap.ServerBootstrap;
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.NioServerSocketChannel;
import io.netty.handler.codec.FixedLengthFrameDecoder;

/**
 * 代码清单 2-2 EchoServer 类
 *
 * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a>
 */
public class EchoServer {
    private static final byte SPACE = (byte)' ';
    private final int port;

    public EchoServer(int port) {
        this.port = port;
    }

    public static void main(String[] args)
        throws Exception {
//        if (args.length != 1) {
//            System.err.println("Usage: " + EchoServer.class.getSimpleName() +
//                " <port>"
//            );
//            return;
//        }
        //设置端口值（如果端口参数的格式不正确，则抛出一个NumberFormatException）
        int port = Integer.parseInt("8888");
        //调用服务器的 start()方法
        new EchoServer(port).start();
    }

    public void start() throws Exception {
        final EchoServerHandler serverHandler = new EchoServerHandler();
        //(1) 创建EventLoopGroup
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            //(2) 创建ServerBootstrap
            ServerBootstrap b = new ServerBootstrap();
            b.group(group)
                //(3) 指定所使用的 NIO 传输 Channel
                .channel(NioServerSocketChannel.class)
                //(4) 使用指定的端口设置套接字地址
                .localAddress(new InetSocketAddress(port))
                //(5) 添加一个EchoServerHandler到于Channel的 ChannelPipeline
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    public void initChannel(SocketChannel ch) throws Exception {
                        //EchoServerHandler 被标注为@Shareable，所以我们可以总是使用同样的实例
                        //这里对于所有的客户端连接来说，都会使用同一个 EchoServerHandler，因为其被标注为@Sharable，
                        //这将在后面的章节中讲到。
                        //长度编码
                        ch.pipeline().addLast(new FixedLengthFrameDecoder(32));
                      
                        ch.pipeline().addLast(serverHandler);
                    }
                });
            //(6) 异步地绑定服务器；调用 sync()方法阻塞等待直到绑定完成
            ChannelFuture f = b.bind().sync();
            System.out.println(EchoServer.class.getName() +
                " started and listening for connections on " + f.channel().localAddress());
            //(7) 获取 Channel 的CloseFuture，并且阻塞当前线程直到它完成
            f.channel().closeFuture().sync();
        } finally {
            //(8) 关闭 EventLoopGroup，释放所有的资源
            group.shutdownGracefully().sync();
        }
    }
    
    
}

对应的serverhandler

package nia.chapter2.echoserver;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;

/**
 * 代码清单 2-1 EchoServerHandler
 *
 * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a>
 */
//标示一个ChannelHandler可以被多个 Channel 安全地共享
@Sharable
public class EchoServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf in = (ByteBuf) msg;
        //将消息记录到控制台
        System.out.println(
                "Server received: " + in.toString(CharsetUtil.UTF_8));
        //将接收到的消息写给发送者，而不冲刷出站消息
        //ctx.write(in);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx)
            throws Exception {
        //将未决消息冲刷到远程节点，并且关闭该 Channel
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
                .addListener(ChannelFutureListener.CLOSE);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx,
        Throwable cause) {
        //打印异常栈跟踪
        cause.printStackTrace();
        //关闭该Channel
        ctx.close();
    }
}

clien端代码以及handler

package nia.chapter2.echoclient;

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 io.netty.handler.codec.FixedLengthFrameDecoder;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;

import java.net.InetSocketAddress;

/**
 * 代码清单 2-4 客户端的主类
 *
 * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a>
 */
public class EchoClient {
    private final String host;
    private final int port;

    public EchoClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void start()
        throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            //创建 Bootstrap
            Bootstrap b = new Bootstrap();
            //指定 EventLoopGroup 以处理客户端事件；需要适用于 NIO 的实现
            b.group(group)
                //适用于 NIO 传输的Channel 类型
                .channel(NioSocketChannel.class)
                //设置服务器的InetSocketAddress
                .remoteAddress(new InetSocketAddress(host, port))
                //在创建Channel时，向 ChannelPipeline中添加一个 EchoClientHandler实例
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    public void initChannel(SocketChannel ch)
                        throws Exception {
                        
                        //长度编码
                          ch.pipeline().addLast(
                                  new FixedLengthFrameDecoder(32));
                        
                        ch.pipeline().addLast(
                             new EchoClientHandler());
                    }
                });
            //连接到远程节点，阻塞等待直到连接完成
            ChannelFuture f = b.connect().sync();
            //阻塞，直到Channel 关闭
            f.channel().closeFuture().sync();
        } finally {
            //关闭线程池并且释放所有的资源
            group.shutdownGracefully().sync();
        }
    }

    public static void main(String[] args)
            throws Exception {
//        if (args.length != 2) {
//            System.err.println("Usage: " + EchoClient.class.getSimpleName() +
//                    " <host> <port>"
//            );
//            return;
//        }

        final String host = "127.0.0.1";
        final int port = Integer.parseInt("8888");
        new EchoClient(host, port).start();
    }
}

package nia.chapter2.echoclient;

import java.nio.charset.Charset;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;

/**
 * 代码清单 2-3 客户端的 ChannelHandler
 *
 * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a>
 */
@Sharable
//标记该类的实例可以被多个 Channel 共享
public class EchoClientHandler
    extends SimpleChannelInboundHandler<ByteBuf> {
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        //当被通知 Channel是活跃的时候，发送一条消息
        
            for(int i = 0 ;i<1000;i++) {
//                ctx.writeAndFlush(Unpooled.copiedBuffer("Netty rocks!",
//                        CharsetUtil.UTF_8));
                
                ctx.writeAndFlush(getByteBuffer(ctx));
                
            }
            
    }

    private ByteBuf getByteBuffer(ChannelHandlerContext ctx) {        
        byte[] bytes = "你好，我的名字是1234567!".getBytes(Charset.forName("utf-8"));        
        ByteBuf buffer = ctx.alloc().buffer();        
        buffer.writeBytes(bytes);        
        return buffer;    
    }

    @Override
    public void channelRead0(ChannelHandlerContext ctx, ByteBuf in) {
        //记录已接收消息的转储
        System.out.println(
                "Client received: " + in.toString(CharsetUtil.UTF_8));
    }

    @Override
    //在发生异常时，记录错误并关闭Channel
    public void exceptionCaught(ChannelHandlerContext ctx,
        Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
    
    public static void main(String[] args) {
        String a = "trumpnoob";
        System.out.println(a.length());
        System.out.println(a.getBytes().length);
    }
}

这里加了编码器 主要指定了字节长度

判断字节长度使用getbyte.length()

比较简单的处理粘包和粘包的情况