一个简单的POJO netty客户端和服务端例子

一个简单的POJO netty客户端和服务端例子

这是一个参考netty官网写的，做了一些改变
版本

代码地址 netty-hello-world

POJO

 		<dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.42.Final</version>
        </dependency>

public class UnixTime {

    private final long value;

    public UnixTime() {
        this(System.currentTimeMillis() / 1000L + 2208988800L);
    }

    public UnixTime(long value) {
        this.value = value;
    }

    public long value() {
        return value;
    }

    @Override
    public String toString() {
        return new Date((value() - 2208988800L) * 1000L).toString();
    }
}

解码和编码器

public class TimeDecoder extends ByteToMessageDecoder {

    @Override
    protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception {
        if (byteBuf.readableBytes() < 4) {
            return;
        }
        list.add(new UnixTime(byteBuf.readUnsignedInt()));
    }
}

public class TimeEncoder extends MessageToByteEncoder<UnixTime> {

    @Override
    protected void encode(ChannelHandlerContext channelHandlerContext, UnixTime unixTime, ByteBuf byteBuf) throws Exception {
        byteBuf.writeInt((int) unixTime.value());
    }
}

服务端handler

public class TimeServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelActive(final ChannelHandlerContext ctx) throws Exception {
        UnixTime time = new UnixTime();
        ctx.writeAndFlush(time);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        UnixTime time = (UnixTime) msg;
        System.out.println("接受到客户端数据：" + time.toString());
        TimeUnit.SECONDS.sleep(2);
        ctx.writeAndFlush(new UnixTime());
    }
}

服务主方法

public class DiscardServer {

    private int port;

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

    public static void main(String[] args) throws Exception {
        int port = 9090;
        new DiscardServer(port)
                .run();
    }

    public void run() throws Exception {
        //第一个BossGroup是用来处理进来的链接
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {

                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline()
                                    .addLast(new TimeEncoder())
                                    .addLast(new TimeDecoder())
                                    .addLast(new TimeServerHandler());
                        }
                    })
                    .option(ChannelOption.SO_BACKLOG, 128)
                    .childOption(ChannelOption.SO_KEEPALIVE, true);
            ChannelFuture channelFuture = b.bind(port)
                    .sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }
}

客户端

public class TimeClientHandler extends ChannelInboundHandlerAdapter {


    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        UnixTime m = (UnixTime) msg;
        System.out.println("接受到服务端数据：" + m.toString());
        TimeUnit.SECONDS.sleep(2);
        ctx.writeAndFlush(new UnixTime());

    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        UnixTime time = new UnixTime();
        ctx.writeAndFlush(time);
    }


    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

客户端主方法

public class TimeClient {
    public static void main(String[] args) throws Exception {
        String host = "127.0.0.1";
        int port = 9090;
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap(); // (1)
            b.group(workerGroup); // (2)
            b.channel(NioSocketChannel.class); // (3)
            b.option(ChannelOption.SO_KEEPALIVE, true); // (4)
            b.handler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline()
                            .addLast(new TimeDecoder())
                            .addLast(new TimeEncoder())
                            .addLast(new TimeClientHandler());
                }
            });

            // Start the client.
            ChannelFuture f = b.connect(host, port).sync(); // (5)

            // Wait until the connection is closed.
            f.channel().closeFuture().sync();
            f.channel().writeAndFlush(new UnixTime());
        } finally {
            workerGroup.shutdownGracefully();
        }
    }
}