netty简单介绍

Netty是由JBOSS提供的一个java开源框架，Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。
今天我们简单的使用Netty 来实现下群发功能.

实现群发流程图

流程图比较详细。看图应该就差不多了。不清楚的，后面有详细代码粘贴。
在这里插入图片描述

代码实现

NettyServer 类

public static void main(String[] args) {
        try {
            new NettyServer().bind(8080);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private void bind(int port) throws InterruptedException {
        //配置服务端线程组
        EventLoopGroup parentGroup=new NioEventLoopGroup();
        EventLoopGroup childGroup=new NioEventLoopGroup();
        ServerBootstrap bootstrap=new ServerBootstrap();
        bootstrap.group(parentGroup,childGroup)
                .channel(NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG,128)
                //配置初始化Channel类
                .childHandler(new MyChannelInitializer());
        ChannelFuture future=bootstrap.bind(port).sync();
        System.out.println("echo test.........66666");
        future.channel().closeFuture().sync();
    }

MyChannelInitializer 类

public class MyChannelInitializer extends ChannelInitializer<SocketChannel> {
    protected void initChannel(SocketChannel  channel) throws Exception {
        //解码器
        //基于换行符号
        channel.pipeline().addLast(new LineBasedFrameDecoder(1024));
        //基于指定字符串(换行符)，这样功能和LineBaseFrameDecoder的功能类似
        //解码转String,注意调整自己的编码格式
        channel.pipeline().addLast(new StringDecoder(Charset.forName("GBK")));

        //编码格式
        channel.pipeline().addLast(new StringEncoder(Charset.forName("GBK")));
        //在管道中添加我们自己的接收数据实现方法
        channel.pipeline().addLast(new MyServerHandler());
    }


}

MyServerHandler 类

public class MyServerHandler extends ChannelInboundHandlerAdapter {
    private SimpleDateFormat sdf = new SimpleDateFormat("YYYY-MM-DD HH:mm:ss");

    @Override
    public void channelRead(ChannelHandlerContext channelHandlerContext, Object obj) throws UnsupportedEncodingException {
        System.out.println(sdf.format(new Date()) + "\n" + obj);
        //接收数据
        String str = "服务端接收到了消息:" + sdf.format(new Date());
        //通知客户端
        //ByteBuf buf = Unpooled.buffer(str.getBytes().length);
        //buf.writeBytes(str.getBytes("GBK"));
        //channelHandlerContext.writeAndFlush(str);
        ChannelHandler.channels.writeAndFlush(str);
    }

    @Override
    public void channelActive(ChannelHandlerContext channelHandlerContext) throws IOException {
        //当有客户端连接时，将其添加到channelGroup中
        ChannelHandler.channels.add(channelHandlerContext.channel());
        NioSocketChannel channel = (NioSocketChannel) channelHandlerContext.channel();
        System.out.println("链接报告开始 {公众号：bugstack虫洞栈 >获取学习源码}");
        System.out.println("链接报告信息：有一客户端链接到本服务端");
        System.out.println("链接报告IP:" + channel.localAddress().getHostName());
        System.out.println("链接报告Port:" + channel.localAddress().getPort());
        System.out.println("链接报告完毕");
        //通知客户端连接成功
        String dateStr = sdf.format(new Date());
        String str = "通知客户端建立连接成功...." + dateStr + channel.localAddress();
        //ByteBuf buf = Unpooled.buffer(str.getBytes().length);
       // buf.writeBytes(str.getBytes("GBK"));
        ChannelHandler.channels.writeAndFlush(str);
    }

    @Override
    public void channelInactive(ChannelHandlerContext context) {
        System.out.println("断开连接...." + context.channel().localAddress());
        //当有客户端断开连接时，将其从channelGroup中移除
        ChannelHandler.channels.remove(context.channel());
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext channelHandlerContext,Throwable throwable){
        channelHandlerContext.close();
        System.out.println("异常信息： \n"+throwable);
    }
}

ChannelHandler 类

public class ChannelHandler {

    public static ChannelGroup channels=
            new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
}

Netty 依赖

        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.36.Final</version>
        </dependency>