netty對象傳輸

netty進行對象傳輸首先對象需要序列化，然後通過ByteBuf的形式進行傳輸！

1 引入pom文件

        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.0.29.Final</version>
        </dependency>

2 對象類

public class User implements Serializable{

    private String username;

    private int age;

    public User(String username,int age){
        this.username = username;
        this.age =age;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "username:"+username+",age:"+age;
    }
}

3 編寫UserDecoder與UserEncoder
3.1 UserDecoder

public class UserDecoder extends ByteToMessageDecoder {
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        ByteBufToBytes read = new ByteBufToBytes();
        Object obj = ByteObjConverter.byteToObject(read.read(in));
        out.add(obj);
    }

}

3.2 UserEncoder

public class UserEncoder extends MessageToByteEncoder<User> {

    @Override
    protected void encode(ChannelHandlerContext ctx, User user, ByteBuf out) throws Exception {
        byte[] datas = ByteObjConverter.objectToByte(user);
        out.writeBytes(datas);
        ctx.flush();
    }
}

3.3 輔助工具類ByteObjConverter

public class ByteObjConverter {

    public static Object byteToObject(byte[] bytes) {
        Object obj = null;
        ByteArrayInputStream bi = new ByteArrayInputStream(bytes);
        ObjectInputStream oi = null;
        try {
            oi = new ObjectInputStream(bi);
            obj = oi.readObject();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bi.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                oi.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return obj;
    }

    public static byte[] objectToByte(Object obj) {
        byte[] bytes = null;
        ByteArrayOutputStream bo = new ByteArrayOutputStream();
        ObjectOutputStream oo = null;
        try {
            oo = new ObjectOutputStream(bo);
            oo.writeObject(obj);
            bytes = bo.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bo.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                oo.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return bytes;
    }
}

3.4 輔助工具類ByteBufToBytes

public class ByteBufToBytes {

    public byte[] read(ByteBuf datas) {
        byte[] bytes = new byte[datas.readableBytes()];
        datas.readBytes(bytes);
        return bytes;
    }
}

4 Server端構建
4.1 Server

public class Server {
    /**
     * 用於分配處理業務線程的線程組個數 
     */
    protected static final int BIZGROUPSIZE = Runtime.getRuntime().availableProcessors()*2; //默認  

    /**
     *業務出現線程大小
     */  
    protected static final int BIZTHREADSIZE = 4;

    /** 
     * NioEventLoopGroup實際上就是個線程池, 
     * NioEventLoopGroup在後臺啓動了n個NioEventLoop來處理Channel事件, 
     * 每一個NioEventLoop負責處理m個Channel, 
     * NioEventLoopGroup從NioEventLoop數組裏挨個取出NioEventLoop來處理Channel 
     */  
    private static final EventLoopGroup bossGroup = new NioEventLoopGroup(BIZGROUPSIZE);  
    private static final EventLoopGroup workerGroup = new NioEventLoopGroup(BIZTHREADSIZE); 

    protected void run() throws Exception { 

        ServerBootstrap b = new ServerBootstrap();  
        b.group(bossGroup, workerGroup);  
        b.channel(NioServerSocketChannel.class);  
        b.childHandler(new ChannelInitializer<SocketChannel>() {  
            @Override  
            public void initChannel(SocketChannel ch) throws Exception {  
                ChannelPipeline pipeline = ch.pipeline();  
                pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));  
                pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));  
                pipeline.addLast("decoder", new UserDecoder());  
                pipeline.addLast("encoder", new UserEncoder());  
                pipeline.addLast(new ServerHandler());  
            }  
        });  

        ChannelFuture f = b.bind("xx.xx.xx.xx",9873).sync();  


        System.out.println("netty server start success...");

        /**
         * wait until the socket close
         */
        f.channel().closeFuture().sync();

        shutdown();

    }

    protected static void shutdown() {  
        workerGroup.shutdownGracefully();  
        bossGroup.shutdownGracefully();  
    }

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

4.2 Server Handler

public class ServerHandler extends SimpleChannelInboundHandler<Object> {

    /**
     * 請求的超時時間
     */
    private static final long TIMEOUT = 2*60*1000L;

    /**
     * cache的過期時間：60s
     */
    private static final long MILSECONDS = 1000*60;

    @Override  
    protected void channelRead0(ChannelHandlerContext ctx, Object msg)  
            throws Exception {  
        User user = (User)msg;
        ctx.channel().writeAndFlush(user);
    }

    /**
     * Close the connection when an exception is raised.
     */
    @Override  
    public void exceptionCaught(ChannelHandlerContext ctx,  
            Throwable cause) throws Exception {    
        ctx.close();  
    }  
}

5 Cilent端構建
5.1 Client

public class Client {    
    public static String HOST = "xx.xx.xx.xx";
    public static int PORT = 9873;  

    public static Bootstrap bootstrap = getBootstrap();  
    public static Channel channel = getChannel(HOST,PORT);  


    /** 
     * 初始化Bootstrap 
     * @return 
     */  
    public static final Bootstrap getBootstrap(){  
        EventLoopGroup group = new NioEventLoopGroup();  
        Bootstrap b = new Bootstrap();  
        b.group(group).channel(NioSocketChannel.class);  
        b.handler(new ChannelInitializer<Channel>() {  
            @Override  
            protected void initChannel(Channel ch) throws Exception {  
                ChannelPipeline pipeline = ch.pipeline();  
                pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));  
                pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));  
                pipeline.addLast("decoder", new UserDecoder());  
                pipeline.addLast("encoder", new UserEncoder());  
                pipeline.addLast("handler", new ClientHandler());  
            }  
        });  
        b.option(ChannelOption.SO_KEEPALIVE, true);  
        return b;  
    }  

    public static final Channel getChannel(String host,int port){  
        Channel channel = null;  
        try {  
            channel = bootstrap.connect(host, port).sync().channel();  
        } catch (Exception e) {   
            return null;  
        }  
        return channel;  
    }  

    public static void sendUser(User user) throws Exception {  
        System.out.println(channel);
        if(channel!=null){  
            channel.writeAndFlush(user).sync();  
        }else{  
            System.out("消息發送失敗,連接尚未建立!");  
        }  
    }  

    public static void main(String[] args) throws Exception {  
        try {  
            Client.sendUser(new User("kevin.yang",24)); 
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
} 

5.2 Client Handler

public class ClientHandler extends SimpleChannelInboundHandler<Object> {  

    @Override  
    protected void channelRead0(ChannelHandlerContext ctx, Object msg)  
            throws Exception {          
       System.out("client接收到服務器返回的消息:"+(User)msg);            
    }  

}