Netty编解码技术和UDP实现

背景

作为网络传输框架，免不了传输对象，对象在传输之前就要序列化，这个序列化的过程就是编码过程。接收到编码后的数据就需要解码，还原传输的数据。

编解码技术就是java序列化技术，序列化的目的有两个，一是进行网络传输，二是对象持久化。

但是Java的序列化缺点很多，如无法跨语言，序列化后码流太大，序列化性能太低

主流的序列化框架：

　　JBoss的Marshalling包

　　google的Protobuf

　　基于Protobuf的Kyro

　　MessagePack框架

JBoss Marshalling的实现

代码示例：

public class Server {

    public static void main(String[] args) throws Exception {

        EventLoopGroup pGroup = new NioEventLoopGroup();
        EventLoopGroup cGroup = new NioEventLoopGroup();

        ServerBootstrap b = new ServerBootstrap();
        b.group(pGroup, cGroup).channel(NioServerSocketChannel.class).option(ChannelOption.SO_BACKLOG, 1024)
                // 设置日志
                .handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer<SocketChannel>() {
                    protected void initChannel(SocketChannel sc) throws Exception {
                        sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
                        sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
                        sc.pipeline().addLast(new ServerHandler());
                    }
                });

        ChannelFuture cf = b.bind(8765).sync();

        cf.channel().closeFuture().sync();
        pGroup.shutdownGracefully();
        cGroup.shutdownGracefully();

    }
}

public class ServerHandler extends ChannelHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {

    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        Req req = (Req) msg;
        System.out.println("Server : " + req.getId() + ", " + req.getName() + ", " + req.getRequestMessage());
        byte[] attachment = GzipUtils.ungzip(req.getAttachment());

        String path = System.getProperty("user.dir") + File.separatorChar + "receive" + File.separatorChar + "001.jpg";
        FileOutputStream fos = new FileOutputStream(path);
        fos.write(attachment);
        fos.close();

        Resp resp = new Resp();
        resp.setId(req.getId());
        resp.setName("resp" + req.getId());
        resp.setResponseMessage("响应内容" + req.getId());
        ctx.writeAndFlush(resp);// .addListener(ChannelFutureListener.CLOSE);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

    }

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

}

public class Client {

    public static void main(String[] args) throws Exception {

        EventLoopGroup group = new NioEventLoopGroup();
        Bootstrap b = new Bootstrap();
        b.group(group).channel(NioSocketChannel.class).handler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel sc) throws Exception {
                sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
                sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
                sc.pipeline().addLast(new ClientHandler());
            }
        });

        ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();

        for (int i = 0; i < 5; i++) {
            Req req = new Req();
            req.setId("" + i);
            req.setName("pro" + i);
            req.setRequestMessage("数据信息" + i);
            String path = System.getProperty("user.dir") + File.separatorChar + "sources" + File.separatorChar
                    + "001.jpg";
            File file = new File(path);
            FileInputStream in = new FileInputStream(file);
            byte[] data = new byte[in.available()];
            in.read(data);
            in.close();
            req.setAttachment(GzipUtils.gzip(data));
            cf.channel().writeAndFlush(req);
        }

        cf.channel().closeFuture().sync();
        group.shutdownGracefully();
    }
}

public class ClientHandler extends ChannelHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {

    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
            Resp resp = (Resp) msg;
            System.out.println("Client : " + resp.getId() + ", " + resp.getName() + ", " + resp.getResponseMessage());
        } finally {
            ReferenceCountUtil.release(msg);
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

    }

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

}

/**
 * Marshalling工厂
 *
 */
public final class MarshallingCodeCFactory {

    /**
     * 创建Jboss Marshalling解码器MarshallingDecoder
     *
     * @return MarshallingDecoder
     */
    public static MarshallingDecoder buildMarshallingDecoder() {
        // 首先通过Marshalling工具类的精通方法获取Marshalling实例对象 参数serial标识创建的是java序列化工厂对象。
        final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
        // 创建了MarshallingConfiguration对象，配置了版本号为5
        final MarshallingConfiguration configuration = new MarshallingConfiguration();
        configuration.setVersion(5);
        // 根据marshallerFactory和configuration创建provider
        UnmarshallerProvider provider = new DefaultUnmarshallerProvider(marshallerFactory, configuration);
        // 构建Netty的MarshallingDecoder对象，俩个参数分别为provider和单个消息序列化后的最大长度
        MarshallingDecoder decoder = new MarshallingDecoder(provider, 1024 * 1024 * 1);
        return decoder;
    }

    /**
     * 创建Jboss Marshalling编码器MarshallingEncoder
     *
     * @return MarshallingEncoder
     */
    public static MarshallingEncoder buildMarshallingEncoder() {
        final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
        final MarshallingConfiguration configuration = new MarshallingConfiguration();
        configuration.setVersion(5);
        MarshallerProvider provider = new DefaultMarshallerProvider(marshallerFactory, configuration);
        // 构建Netty的MarshallingEncoder对象，MarshallingEncoder用于实现序列化接口的POJO对象序列化为二进制数组
        MarshallingEncoder encoder = new MarshallingEncoder(provider);
        return encoder;
    }
}

public class Req implements Serializable {

    private static final long serialVersionUID = 1L;

    private String id;
    private String name;
    private String requestMessage;
    private byte[] attachment;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getRequestMessage() {
        return requestMessage;
    }

    public void setRequestMessage(String requestMessage) {
        this.requestMessage = requestMessage;
    }

    public byte[] getAttachment() {
        return attachment;
    }

    public void setAttachment(byte[] attachment) {
        this.attachment = attachment;
    }
}

public class Resp implements Serializable {

    private static final long serialVersionUID = 1L;

    private String id;
    private String name;
    private String responseMessage;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getResponseMessage() {
        return responseMessage;
    }

    public void setResponseMessage(String responseMessage) {
        this.responseMessage = responseMessage;
    }

}

工具类：

public class GzipUtils {

    public static byte[] gzip(byte[] data) throws Exception {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        GZIPOutputStream gzip = new GZIPOutputStream(bos);
        gzip.write(data);
        gzip.finish();
        gzip.close();
        byte[] ret = bos.toByteArray();
        bos.close();
        return ret;
    }

    public static byte[] ungzip(byte[] data) throws Exception {
        ByteArrayInputStream bis = new ByteArrayInputStream(data);
        GZIPInputStream gzip = new GZIPInputStream(bis);
        byte[] buf = new byte[1024];
        int num = -1;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while ((num = gzip.read(buf, 0, buf.length)) != -1) {
            bos.write(buf, 0, num);
        }
        gzip.close();
        bis.close();
        byte[] ret = bos.toByteArray();
        bos.flush();
        bos.close();
        return ret;
    }

    public static void main(String[] args) throws Exception {

        // 读取文件
        String readPath = System.getProperty("user.dir") + File.separatorChar + "sources" + File.separatorChar
                + "006.jpg";
        File file = new File(readPath);
        FileInputStream in = new FileInputStream(file);
        byte[] data = new byte[in.available()];
        in.read(data);
        in.close();

        System.out.println("文件原始大小:" + data.length);
        // 测试压缩

        byte[] ret1 = GzipUtils.gzip(data);
        System.out.println("压缩之后大小:" + ret1.length);

        byte[] ret2 = GzipUtils.ungzip(ret1);
        System.out.println("还原之后大小:" + ret2.length);

        // 写出文件
        String writePath = System.getProperty("user.dir") + File.separatorChar + "receive" + File.separatorChar
                + "006.jpg";
        FileOutputStream fos = new FileOutputStream(writePath);
        fos.write(ret2);
        fos.close();
    }
}

UDP的实现

代码示例：

public class Server {
    public void run(int port) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group).channel(NioDatagramChannel.class).option(ChannelOption.SO_BROADCAST, true)
                    .handler(new ServerHandler());
            b.bind(port).sync().channel().closeFuture().await();
        } finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        new Server().run(8765);
        new Server().run(8764);
    }
}

public class ServerHandler extends
    SimpleChannelInboundHandler<DatagramPacket> {

    // 谚语列表
    private static final String[] DICTIONARY = {
        "只要功夫深，铁棒磨成针。",
        "旧时王谢堂前燕，飞入寻常百姓家。",
        "洛阳亲友如相问，一片冰心在玉壶。",
        "一寸光阴一寸金，寸金难买寸光阴。",
        "老骥伏枥，志在千里。烈士暮年，壮心不已!"
    };

    private String nextQuote() {
        int quoteId = ThreadLocalRandom.current().nextInt(DICTIONARY.length);
        return DICTIONARY[quoteId];
    }

    @Override
    public void messageReceived(ChannelHandlerContext ctx, DatagramPacket packet)
        throws Exception {
        String req = packet.content().toString(CharsetUtil.UTF_8);
        System.out.println(req);
        if ("谚语字典查询?".equals(req)) {
            ctx.writeAndFlush(
                    new DatagramPacket(Unpooled.copiedBuffer("谚语查询结果: " + nextQuote(),
                    CharsetUtil.UTF_8), packet.sender()));
        }
    }

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

public class Client {

    public void run(int port) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group).channel(NioDatagramChannel.class).option(ChannelOption.SO_BROADCAST, true)
                    .handler(new ClientHandler());
            Channel ch = b.bind(0).sync().channel();
            // 向网段内的所有机器广播UDP消息
            ch.writeAndFlush(new DatagramPacket(Unpooled.copiedBuffer("谚语字典查询?", CharsetUtil.UTF_8),
                    new InetSocketAddress("255.255.255.255", port))).sync();
            if (!ch.closeFuture().await(15000)) {
                System.out.println("查询超时!");
            }
        } finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        new Client().run(8765);
    }
}

public class ClientHandler extends SimpleChannelInboundHandler<DatagramPacket> {

    @Override
    public void messageReceived(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception {
        String response = msg.content().toString(CharsetUtil.UTF_8);
        if (response.startsWith("谚语查询结果: ")) {
            System.out.println(response);
            ctx.close();
        }
    }

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