Netty使用(一)

什么是Netty

　　Netty由JBOSS提供的基于Java NIO的开源框架，Netty提供异步非阻塞、事件驱动、高性能、高可靠、高可定制性的网络应用程序和工具，

可用于开发服务端和客户端。

配置服务端

 

public class SimpleChatServer {
    private int port;

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

    public void run() throws Exception {

        //EventLoopGroup 处理I/O操作的多线程事件循环器 bossGroup 用来接收进来的连接 workerGroup 用来处理已经被接收的连接
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            // 一个启动 NIO 服务的辅助启动类
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new SimpleChatServerInitializer())
                    .option(ChannelOption.SO_BACKLOG, 128)
                    .childOption(ChannelOption.SO_KEEPALIVE, true);

            System.out.println("服务端 启动");

            // 绑定端口，开始接收进来的连接
            ChannelFuture f = b.bind(port).sync();

            // 等待服务器  socket 关闭 。
            // 在这个例子中，这不会发生，但你可以优雅地关闭你的服务器。
            f.channel().closeFuture().sync();

        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();

            System.out.println("SimpleChatServer 关闭了");
        }
    }

    public static void main(String[] args) throws Exception {
        int port;
        if (args.length > 0) {
            port = Integer.parseInt(args[0]);
        } else {
            port = 8080;
        }
        new SimpleChatServer(port).run();

    }
}

配置服务端消息处理

public class SimpleChatServerHandler extends SimpleChannelInboundHandler<String> {

    public static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String s) throws Exception {
        Channel incoming = channelHandlerContext.channel();
        for (Channel channel : channels) {
            if (channel != incoming){
                channel.writeAndFlush("[" + incoming.remoteAddress() + "]" + s + "\n");
            } else {
                channel.writeAndFlush("[you]" + s + "\n");
            }
        }
    }

    /**
     * 服务端监听到客户端活动
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
         Channel incoming = ctx.channel();
        System.out.println("SimpleChatClient:"+incoming.remoteAddress()+"在线");
    }

    /**
     * 服务端监听到客户端不活动
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        Channel incoming = ctx.channel();
        System.out.println("SimpleChatClient:"+incoming.remoteAddress()+"掉线");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        Channel incoming = ctx.channel();
        System.out.println("SimpleChatClient:"+incoming.remoteAddress()+"异常");
        // 当出现异常就关闭连接
        cause.printStackTrace();
        ctx.close();
    }

    /**
     * 每当从服务端读到客户端写入信息时，将信息转发给其他客户端的 Channel
     * @param ctx
     * @throws Exception
     */
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel incoming = ctx.channel();
        for (Channel channel : channels) {
            channel.writeAndFlush("[SERVER] - " + incoming.remoteAddress() + " 加入\n");
        }
        channels.add(ctx.channel());
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel incoming = ctx.channel();
        for (Channel channel : channels) {
            channel.writeAndFlush("[SERVER] - " + incoming.remoteAddress() + " 离开\n");
        }
        channels.remove(ctx.channel());
    }

配置服务端初始化设置

public class SimpleChatServerInitializer  extends
        ChannelInitializer<SocketChannel> {

    @Override
    public void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        pipeline.addLast("decoder", new StringDecoder());
        pipeline.addLast("encoder", new StringEncoder());
        pipeline.addLast("handler", new SimpleChatServerHandler());

        System.out.println("SimpleChatClient:"+ch.remoteAddress() +"连接上");
    }
}

配置用户端

public class SimpleChatClient {
    public static void main(String[] args) throws Exception{
        new SimpleChatClient("localhost", 8080).run();
    }

    private final String host;
    private final int port;

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

    public void run() throws Exception{
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap  = new Bootstrap()
                    .group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new SimpleChatClientInitializer());
            Channel channel = bootstrap.connect(host, port).sync().channel();
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            while(true){
                channel.writeAndFlush(in.readLine() + "\r\n");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            group.shutdownGracefully();
        }

    }
}

用来启动服务

配置客户端初始化文件

public class SimpleChatClientInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    public void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        pipeline.addLast("decoder", new StringDecoder());
        pipeline.addLast("encoder", new StringEncoder());
        pipeline.addLast("handler", new SimpleChatClientHandler());
    }
}

处理得到消息的配置

public class SimpleChatClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {
        System.out.println(s);
    }

}