Netty编解码及protostuff

港控/mmm° 2022-11-15 11:40 234阅读 0赞

# Netty编解码是什么？ #

要想了解编解码，首先要知客户端和服务端是怎么处理信息的，当通过Netty发送或者接收信息的时候，首先要将接收到的消息尽心decode()方法进行解码，然后发送ChannelPipeline中的下一个ChannelInboundHandler，也就信息要从Channel中ChannelPipeline的head Handler一直处理到tail Handler，涉及到的编解码组件有Channel、ChannelHandler、ChannelPipe等。这几个组件的关系大致如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4NjMwODEw_size_16_color_FFFFFF_t_70][]

# 常见的编解码器有什么？ #

有Netty自带的StringEncoder，StringDecoder，ObjectEncoder和ObjectDecoder，也有第三方的protostuff。下面来看一下这几个的用法

# 如何使用 #

如果需要使用protostuff，首先要引入一下pom

<dependency>
    	<groupId>com.dyuproject.protostuff</groupId>
    	<artifactId>protostuff-api</artifactId>
    	<version>1.0.10</version>
    </dependency>
    <dependency>
    	<groupId>com.dyuproject.protostuff</groupId>
    	<artifactId>protostuff-core</artifactId>
    	<version>1.0.10</version>
    </dependency>
    <dependency>
    	<groupId>com.dyuproject.protostuff</groupId>
    	<artifactId>protostuff-runtime</artifactId>
    	<version>1.0.10</version>
    </dependency>

## 服务端代码 ##

public class NettyServer {
        public static void main(String[] args) throws Exception {
            //接受连接线程池
            EventLoopGroup bossGroup = new NioEventLoopGroup(1);
            //处理业务线程池，默认是cpu凉杯
            EventLoopGroup workerGroup = new NioEventLoopGroup();
            try {
                ServerBootstrap serverBootstrap = new ServerBootstrap();
                serverBootstrap.group(bossGroup, workerGroup)
                        .channel(NioServerSocketChannel.class)
                        .childHandler(new ChannelInitializer<SocketChannel>() {
                            @Override
                            protected void initChannel(SocketChannel ch) throws Exception {
                                ChannelPipeline pipeline = ch.pipeline();
                                //加入解码器，接受新的信息时触发
    //                            pipeline.addLast(new StringDecoder());
                                //加入编码器，当发出信息时候进行编码后再发出
    //                            pipeline.addLast(new StringEncoder());
                                //加入netty自带object编码器 maxObjectSize是channel最大容量
    //                            pipeline.addLast(new ObjectDecoder(10240, ClassResolvers.cacheDisabled(null)));
                                //加入服务端的业务处理器
                                pipeline.addLast(new NettyServerHandler());
                            }
                        });
    
                System.out.println("netty server start。。");
                //
                ChannelFuture channelFuture = serverBootstrap.bind(9000).sync();
                channelFuture.channel().closeFuture().sync();
            } finally {
                bossGroup.shutdownGracefully();
                workerGroup.shutdownGracefully();
            }
        }
    }
    
    
    
    
    public class NettyServerHandler extends ChannelInboundHandlerAdapter {
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            System.out.println("有连接进来");
        }
    
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            //使用StringDecoder解码
    //        System.out.println("从客户端读取到String：" + msg.toString());
            //使用netty自带的ObjectDecoder解码
    //        System.out.println("从客户端读取到Book：" + ((Book)msg).toString());
            //测试用protostuff对对象编解码
            ByteBuf buf = (ByteBuf) msg;
            byte[] bytes = new byte[buf.readableBytes()];
            buf.readBytes(bytes);
            System.out.println("从客户端读取到 Book：" + ProtostuffUtil.deserializer(bytes, Book.class));
        }
    
    }

## 客户端代码 ##

public class NettyClient {
        public static void main(String[] args) throws Exception {
    
            EventLoopGroup group = new NioEventLoopGroup();
            try {
                Bootstrap bootstrap = new Bootstrap();
                bootstrap.group(group).channel(NioSocketChannel.class)
                        .handler(new ChannelInitializer<SocketChannel>() {
                            @Override
                            protected void initChannel(SocketChannel ch) throws Exception {
                                ChannelPipeline pipeline = ch.pipeline();
                                //加入解码器，接受新的信息时触发
    //                            pipeline.addLast(new StringDecoder());
                                //加入编码器，当发出信息时候进行编码后再发出
    //                            pipeline.addLast(new StringEncoder());
                                //加入netty自带object编码器 实体类不需要实现Serializable
    //                            pipeline.addLast(new ObjectEncoder());
                                //加入客服端的业务处理器
                                pipeline.addLast(new NettyClientHandler());
                            }
                        });
    
                System.out.println("netty client start。。");
                //同步连接服务端
                ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 9000).sync();
                channelFuture.channel().closeFuture().sync();
            } finally {
                group.shutdownGracefully();
            }
        }
    }
    
    
    public class NettyClientHandler extends ChannelInboundHandlerAdapter {
    
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            System.out.println("收到服务器消息:" + msg);
        }
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            //使用StringEncoder编码
    //        ctx.writeAndFlush("测试String编解码");
            //测试netty自带对象编解码
    //        ctx.writeAndFlush(new Book("西行纪",13));
            //测试用protostuff编码
            ByteBuf buf = Unpooled.copiedBuffer(ProtostuffUtil.serializer(new Book("西行纪2", 11)));
            ctx.writeAndFlush(buf);
    
        }
    }

## Protostuff工具类 ##

public class ProtostuffUtil {
    
        private static Map<Class<?>, Schema<?>> cachedSchema = new ConcurrentHashMap<Class<?>, Schema<?>>();
    
        private static <T> Schema<T> getSchema(Class<T> clazz) {
            @SuppressWarnings("unchecked")
            Schema<T> schema = (Schema<T>) cachedSchema.get(clazz);
            if (schema == null) {
                schema = RuntimeSchema.getSchema(clazz);
                if (schema != null) {
                    cachedSchema.put(clazz, schema);
                }
            }
            return schema;
        }
    
        /**
         * 序列化
         *
         * @param obj
         * @return
         */
        public static <T> byte[] serializer(T obj) {
            @SuppressWarnings("unchecked")
            Class<T> clazz = (Class<T>) obj.getClass();
            LinkedBuffer buffer = LinkedBuffer.allocate(LinkedBuffer.DEFAULT_BUFFER_SIZE);
            try {
                Schema<T> schema = getSchema(clazz);
                return ProtostuffIOUtil.toByteArray(obj, schema, buffer);
            } catch (Exception e) {
                throw new IllegalStateException(e.getMessage(), e);
            } finally {
                buffer.clear();
            }
        }
    
        /**
         * 反序列化
         *
         * @param data
         * @param clazz
         * @return
         */
        public static <T> T deserializer(byte[] data, Class<T> clazz) {
            try {
                T obj = clazz.newInstance();
                Schema<T> schema = getSchema(clazz);
                ProtostuffIOUtil.mergeFrom(data, obj, schema);
                return obj;
            } catch (Exception e) {
                throw new IllegalStateException(e.getMessage(), e);
            }
        }
    }

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