第13周-Java网络编程进化史：从IO到NIO再到Netty

一.学习和理解网上参考案例，实践练习其中的demo代码

1)分别基于IO、NIO、Netty的Java网络程序（如基于TCP的C/S模式的聊天程序）

IO：

1.实现

服务器

package io;

import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class IOServer {
    
    @SuppressWarnings("resource")
    public static void main(String[] args) throws Exception {
    

        ExecutorService newCachedThreadPool = Executors.newCachedThreadPool();
        //创建socket服务,监听8081端口
        ServerSocket server=new ServerSocket(8081);
        System.out.println("服务器启动！");
        int count=0;
        while(true){
    
            //获取一个套接字（阻塞）
            final Socket socket = server.accept();
            System.out.println("欢迎第"+(++count)+"个客户");
            newCachedThreadPool.execute(new Runnable() {
    

                @Override
                public void run() {
    
                    //业务处理
                    handler(socket);
                }
            });

        }
    }

    /** * 读取数据 * @param socket * @throws Exception */
    public static void handler(Socket socket){
    
        try {
    
            byte[] bytes = new byte[1024];
            InputStream inputStream = socket.getInputStream();

            while(true){
    
                //读取数据（阻塞）
                int read = inputStream.read(bytes);
                if(read != -1){
    
                    System.out.println(new String(bytes, 0, read));
                }else{
    
                    break;
                }
            }
        } catch (Exception e) {
    
            e.printStackTrace();
        }finally{
    
            try {
    
                System.out.println("socket关闭");
                socket.close();
            } catch (IOException e) {
    
                e.printStackTrace();
            }
        }
    }}

2.客户端

package io;

import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;

public class IOClient {
    
    public static void main(String[] args) throws IOException {
    
        //发送十次
        for (int i=0;i<10;i++){
    
            Socket socket=new Socket("192.168.0.178", 8081);
            //写数据
            OutputStream os=socket.getOutputStream();
            os.write(("xyj"+i).getBytes());
            //释放资源
            socket.close();
        }
        
    }

}

2.结果

NIO:

1.实现

服务器

package nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
/** * author:醉意丶千层梦 */

public class NIOServer {
    
    // 通道管理器
    private Selector selector;

    /** * 启动服务端测试 * * @throws IOException */
    public static void main(String[] args) throws IOException {
    
        NIOServer server = new NIOServer();
        server.initServer(8081);
        server.listen();
    }


    /** * 获得一个ServerSocket通道，并对该通道做一些初始化的工作 * * @param port * 绑定的端口号 * @throws IOException */
    public void initServer(int port) throws IOException {
    
        // 获得一个ServerSocket通道
        ServerSocketChannel serverChannel = ServerSocketChannel.open();
        // 设置通道为非阻塞
        serverChannel.configureBlocking(false);
        // 将该通道对应的ServerSocket绑定到port端口
        serverChannel.socket().bind(new InetSocketAddress(port));
        // 获得一个通道管理器
        this.selector = Selector.open();
        // 将通道管理器和该通道绑定，并为该通道注册SelectionKey.OP_ACCEPT事件,注册该事件后，
        // 当该事件到达时，selector.select()会返回，如果该事件没到达selector.select()会一直阻塞。
        serverChannel.register(selector, SelectionKey.OP_ACCEPT);
    }

    /** * 采用轮询的方式监听selector上是否有需要处理的事件，如果有，则进行处理 * * @throws IOException */
    public void listen() throws IOException {
    
        System.out.println("服务端启动成功！");
        // 轮询访问selector
        while (true) {
    
            // 当注册的事件到达时，方法返回；否则,该方法会一直阻塞
            selector.select();
            // 获得selector中选中的项的迭代器，选中的项为注册的事件
            Iterator<?> ite = this.selector.selectedKeys().iterator();
            while (ite.hasNext()) {
    
                SelectionKey key = (SelectionKey) ite.next();
                // 删除已选的key,以防重复处理
                ite.remove();

                handler(key);
            }
        }
    }

    /** * 处理请求 * * @param key * @throws IOException */
    public void handler(SelectionKey key) throws IOException {
    

        // 客户端请求连接事件
        if (key.isAcceptable()) {
    
            handlerAccept(key);
            // 获得了可读的事件
        } else if (key.isReadable()) {
    
            handelerRead(key);
        }
    }

    /** * 处理连接请求 * * @param key * @throws IOException */
    public void handlerAccept(SelectionKey key) throws IOException {
    
        ServerSocketChannel server = (ServerSocketChannel) key.channel();
        // 获得和客户端连接的通道
        SocketChannel channel = server.accept();
        // 设置成非阻塞
        channel.configureBlocking(false);

        // 在这里可以给客户端发送信息哦
        System.out.println("新的客户端连接");
        // 在和客户端连接成功之后，为了可以接收到客户端的信息，需要给通道设置读的权限。
        channel.register(this.selector, SelectionKey.OP_READ);
    }

    /** * 处理读的事件 * * @param key * @throws IOException */
    public void handelerRead(SelectionKey key) throws IOException {
    
        // 服务器可读取消息:得到事件发生的Socket通道
        SocketChannel channel = (SocketChannel) key.channel();
        // 创建读取的缓冲区
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        int read = channel.read(buffer);
        if(read > 0){
    
            byte[] data = buffer.array();
            String msg = new String(data).trim();
            System.out.println("服务端收到信息：" + msg);

            //回写数据
            ByteBuffer outBuffer = ByteBuffer.wrap("好的".getBytes());
            channel.write(outBuffer);// 将消息回送给客户端
        }else{
    
            System.out.println("客户端关闭");
            key.cancel();
        }
    }
}

客户端

package nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;

public class NIOClient {
    
    public static void main(String[] args) throws Exception {
    
        final int count[]=new int[1];
        count[0]=1;
        for(int i=0;i<5;i++){
    
            new Thread(new Runnable() {
    
                @Override
                public void run() {
    
                    SocketChannel socketChannel = null;
                    //发送的数据
                    String str = "xyj"+count[0]++;
                    ByteBuffer byteBuffer = ByteBuffer.wrap(str.getBytes());

                    //接受的数据
                    ByteBuffer buffer = ByteBuffer.allocate(1024);
                    try {
    
                        //建立连接
                        socketChannel = SocketChannel.open();
                        socketChannel.configureBlocking(false);
                        if (!socketChannel.connect(new InetSocketAddress("127.0.0.1", 8081))) {
    
                            //等待连接
                            while (!socketChannel.finishConnect()) {
    
                            }
                        }
                        //写入数据
                        socketChannel.write(byteBuffer);
                    } catch (IOException e) {
    
                        e.printStackTrace();
                    }

                    //10s后自动断开连接
                    int time=1;
                    while (time<10){
    
                        time++;
                        try {
    
                            //读取数据
                            int read=socketChannel.read(buffer);
                            if(read > 0) {
    
                                byte[] data = buffer.array();
                                String msg = new String(data).trim();
                                System.out.println("客户端收到信息：" + msg);
                            }
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
    
                            e.printStackTrace();
                        } catch (IOException e) {
    
                            e.printStackTrace();
                        }
                    }
                    try {
    
                        socketChannel.close();
                    } catch (IOException e) {
    
                        e.printStackTrace();
                    }
                }
            }).start();
            Thread.sleep(100);
        }
    }

}

2.结果

NETTY：

1.实现

服务器

package netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import java.util.Scanner;
/** * author:醉意丶千层梦 */


public class NettyServer {
    
    public static void main(String[] args) {
    
        //用于处理服务器端接收客户端连接
        NioEventLoopGroup bossGroup = new NioEventLoopGroup(1);
        //进行网络通信（读写）
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
    
            //辅助工具类，用于服务器通道的一系列配置
            ServerBootstrap bootstrap = new ServerBootstrap();
            //绑定两个线程组
            bootstrap.group(bossGroup,workerGroup)
                    //设置boss selector建立channel使用的对象
                    .channel(NioServerSocketChannel.class)
                    //boss 等待连接的 队列长度
                    .option(ChannelOption.SO_BACKLOG,1024)
                    //处理消息对象
                    .childHandler(new ChannelInitializer<SocketChannel>() {
    
                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
    
                    //创建管道
                    ChannelPipeline pipeline = ch.pipeline();
                    //解码方式
                    pipeline.addLast("decoder",new StringDecoder());
                    //编码方式
                    pipeline.addLast("encoder",new StringEncoder());
                    //自定义处理消息对象
                    pipeline.addLast(new ServerHandler());
                }
            });
            System.out.println("服务器正在启动");
            //绑定端口号
            ChannelFuture cf = bootstrap.bind(8083).sync();

            cf.addListener(cd->{
    
                if(cd.isSuccess()){
    
                    System.out.println("启动成功");
                }else{
    
                    System.out.println("启动失败");
                }
            });
            //服务端给所有客户端发信息
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNextLine()){
    
                String msg = scanner.nextLine();
                ServerHandler.sendAll(msg);
            }
            //阻塞当前线程
            cf.channel().closeFuture().sync();
        } catch (InterruptedException e) {
    
            e.printStackTrace();
        } finally {
    
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }


}

package com.company;
import io.netty.channel.*;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;
import java.text.SimpleDateFormat;
import java.util.Date;
/** * author:醉意丶千层梦 */

public class ServerHandler extends SimpleChannelInboundHandler<String> {
    
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
    
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress()+" == " +msg);
        channelGroup.forEach(ch->{
    
            if (channel!=ch) {
    
                ch.writeAndFlush("[ 客户端 ]" + channel.remoteAddress() + "发送了消息 : " + msg + "\n");
            }else{
    
                ch.writeAndFlush("[ 我 ] 发送了消息: " + msg + "\n");
            }
        });

    }
    //用于服务端发信息给所有客户端
    public static void sendAll(String msg){
    
        channelGroup.forEach(channel -> {
    
            channel.writeAndFlush("服务器: "+msg+"\n");
        });
    }

    /** * 当有新的用户连接触发 * @param ctx */
    public void channelActive(ChannelHandlerContext ctx){
    
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("[ 客户端 ]"+channel.remoteAddress()+" 上线了 "+sf.format(new Date())+"\n");
        //把新来的连接加入
        channelGroup.add(channel);
        System.out.println(ctx.channel().remoteAddress()+" 上线了" + "\n");
    }

    /** * 当用户断开连接触发 * @param ctx */
    public void channelInactive(ChannelHandlerContext ctx) {
    
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("[ 客户端 ] " +channel.remoteAddress()+ " 下线了"+"\n");
        System.out.println(channel.remoteAddress()+" 下线了.\n");
        System.out.println("channelGroup size = "+ channelGroup.size());
    }
}

客户端

package netty;

import io.netty.channel.*;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;
import java.text.SimpleDateFormat;
import java.util.Date;
/** * author:醉意丶千层梦 */

public class ServerHandler extends SimpleChannelInboundHandler<String> {
    
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
    
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress()+" == " +msg);
        channelGroup.forEach(ch->{
    
            if (channel!=ch) {
    
                ch.writeAndFlush("[ 客户端 ]" + channel.remoteAddress() + "发送了消息 : " + msg + "\n");
            }else{
    
                ch.writeAndFlush("[ 我 ] 发送了消息: " + msg + "\n");
            }
        });

    }
    //用于服务端发信息给所有客户端
    public static void sendAll(String msg){
    
        channelGroup.forEach(channel -> {
    
            channel.writeAndFlush("服务器: "+msg+"\n");
        });
    }

    /** * 当有新的用户连接触发 * @param ctx */
    public void channelActive(ChannelHandlerContext ctx){
    
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("[ 客户端 ]"+channel.remoteAddress()+" 上线了 "+sf.format(new Date())+"\n");
        //把新来的连接加入
        channelGroup.add(channel);
        System.out.println(ctx.channel().remoteAddress()+" 上线了" + "\n");
    }

    /** * 当用户断开连接触发 * @param ctx */
    public void channelInactive(ChannelHandlerContext ctx) {
    
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("[ 客户端 ] " +channel.remoteAddress()+ " 下线了"+"\n");
        System.out.println(channel.remoteAddress()+" 下线了.\n");
        System.out.println("channelGroup size = "+ channelGroup.size());
    }
}

package com.company;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class ClientHandler extends SimpleChannelInboundHandler<String> {
    
@Override
protected void channelRead0(ChannelHandlerContext channelHandlerContext, String msg) throws Exception {
    
        System.out.println(msg.trim());
        }
        }

2.结果

2）基于Web的聊天室（比如用Springboot+netty实现）

1.User类

import java.util.Objects;

public class User {
    

    public String id;
    public String nickname;

    public User(String id, String nickname) {
    
        super();
        this.id = id;
        this.nickname = nickname;
    }

    public String getId() {
    
        return id;
    }

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

    public String getNickname() {
    
        return nickname;
    }

    public void setNickname(String nickname) {
    
        this.nickname = nickname;
    }

    @Override
    public boolean equals(Object o) {
    
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;
        User user = (User) o;
        return id.equals(user.getId());
    }

    @Override
    public int hashCode() {
    

        return Objects.hash(id);
    }

    public String getUid() {
    

        return id;
    }
}

2.SocketSession类

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.AttributeKey;

import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

public class SocketSession {
    

    public static final AttributeKey<SocketSession> SESSION_KEY = AttributeKey.valueOf("SESSION_KEY");

    /** * 用户实现服务端会话管理的核心 */
// 通道
    private Channel channel;
    // 用户
    private User user;

    // session唯一标示
    private final String sessionId;

    private String group;

    /** * session中存储的session 变量属性值 */
    private Map<String, Object> map = new HashMap<String, Object>();

    public SocketSession(Channel channel) {
    //注意传入参数channel。不同客户端会有不同channel
        this.channel = channel;
        this.sessionId = buildNewSessionId();
        channel.attr(SocketSession.SESSION_KEY).set(this);
    }

    // 反向导航
    public static SocketSession getSession(ChannelHandlerContext ctx) {
    //注意ctx，不同的客户端会有不同ctx
        Channel channel = ctx.channel();
        return channel.attr(SocketSession.SESSION_KEY).get();
    }

    // 反向导航
    public static SocketSession getSession(Channel channel) {
    
        return channel.attr(SocketSession.SESSION_KEY).get();
    }

    public String getId() {
    
        return sessionId;
    }

    private static String buildNewSessionId() {
    
        String uuid = UUID.randomUUID().toString();
        return uuid.replaceAll("-", "");
    }

    public synchronized void set(String key, Object value) {
    
        map.put(key, value);
    }

    public synchronized <T> T get(String key) {
    
        return (T) map.get(key);
    }

    public boolean isValid() {
    
        return getUser() != null ? true : false;
    }

    public User getUser() {
    
        return user;
    }

    public void setUser(User user) {
    
        this.user = user;
    }

    public String getGroup() {
    
        return group;
    }

    public void setGroup(String group) {
    
        this.group = group;
    }

    public Channel getChannel() {
    
        return channel;
    }
}

3.SessionGroup

import com.google.gson.Gson;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.ChannelGroupFuture;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.concurrent.ImmediateEventExecutor;
import org.springframework.util.StringUtils;

import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public final class SessionGroup {
    

    private static SessionGroup singleInstance = new SessionGroup();

    // 组的映射
    private ConcurrentHashMap<String, ChannelGroup> groupMap = new ConcurrentHashMap<>();

    public static SessionGroup inst() {
    
        return singleInstance;
    }

    public void shutdownGracefully() {
    

        Iterator<ChannelGroup> groupIterator = groupMap.values().iterator();
        while (groupIterator.hasNext()) {
    
            ChannelGroup group = groupIterator.next();
            group.close();
        }
    }

    public void sendToOthers(Map<String, String> result, SocketSession s) {
    
        // 获取组
        ChannelGroup group = groupMap.get(s.getGroup());
        if (null == group) {
    
            return;
        }
        Gson gson=new Gson();
        String json = gson.toJson(result);
        // 自己发送的消息不返回给自己
// Channel channel = s.getChannel();
        // 从组中移除通道
// group.remove(channel);
        ChannelGroupFuture future = group.writeAndFlush(new TextWebSocketFrame(json));
        future.addListener(f -> {
    
            System.out.println("完成发送："+json);
// group.add(channel);//发送消息完毕重新添加。

        });
    }

    public void addSession(SocketSession session) {
    

        String groupName = session.getGroup();
        if (StringUtils.isEmpty(groupName)) {
    
            // 组为空，直接返回
            return;
        }
        ChannelGroup group = groupMap.get(groupName);
        if (null == group) {
    
            group = new DefaultChannelGroup(ImmediateEventExecutor.INSTANCE);
            groupMap.put(groupName, group);
        }
        group.add(session.getChannel());
    }

    /** * 关闭连接， 关闭前发送一条通知消息 */
    public void closeSession(SocketSession session, String echo) {
    
        ChannelFuture sendFuture = session.getChannel().writeAndFlush(new TextWebSocketFrame(echo));
        sendFuture.addListener(new ChannelFutureListener() {
    
            public void operationComplete(ChannelFuture future) {
    
                System.out.println("关闭连接："+echo);
                future.channel().close();
            }
        });
    }

    /** * 关闭连接 */
    public void closeSession(SocketSession session) {
    

        ChannelFuture sendFuture = session.getChannel().close();
        sendFuture.addListener(new ChannelFutureListener() {
    
            public void operationComplete(ChannelFuture future) {
    
                System.out.println("发送所有完成："+session.getUser().getNickname());
            }
        });

    }

    /** * 发送消息 * @param ctx 上下文 * @param msg 待发送的消息 */
    public void sendMsg(ChannelHandlerContext ctx, String msg) {
    
        ChannelFuture sendFuture = ctx.writeAndFlush(new TextWebSocketFrame(msg));
        sendFuture.addListener(f -> {
    //发送监听
            System.out.println("对所有发送完成："+msg);
        });
    }
}

4.WebSocketTextHandler类

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;

import java.util.HashMap;
import java.util.Map;

public class WebSocketTextHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
    
        SocketSession session = SocketSession.getSession(ctx);
        TypeToken<HashMap<String, String>> typeToken = new TypeToken<HashMap<String, String>>() {
    
        };

        Gson gson=new Gson();
        java.util.Map<String,String> map = gson.fromJson(msg.text(), typeToken.getType());
        User user = null;
        switch (map.get("type")) {
    
            case "msg":
                Map<String, String> result = new HashMap<>();
                user = session.getUser();
                result.put("type", "msg");
                result.put("msg", map.get("msg"));
                result.put("sendUser", user.getNickname());
                SessionGroup.inst().sendToOthers(result, session);
                break;
            case "init":
                String room = map.get("room");
                session.setGroup(room);
                String nick = map.get("nick");
                user = new User(session.getId(), nick);
                session.setUser(user);
                SessionGroup.inst().addSession(session);
                break;
        }
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
    

        // 是否握手成功，升级为 Websocket 协议
        if (evt == WebSocketServerProtocolHandler.ServerHandshakeStateEvent.HANDSHAKE_COMPLETE) {
    
            // 握手成功，移除 HttpRequestHandler，因此将不会接收到任何消息
            // 并把握手成功的 Channel 加入到 ChannelGroup 中
            new SocketSession(ctx.channel());
        } else if (evt instanceof IdleStateEvent) {
    
            IdleStateEvent stateEvent = (IdleStateEvent) evt;
            if (stateEvent.state() == IdleState.READER_IDLE) {
    
                System.out.println("bb22");
            }
        } else {
    
            super.userEventTriggered(ctx, evt);
        }
    }
}

5.WebSocketServer类

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketServerCompressionHandler;
import io.netty.handler.stream.ChunkedWriteHandler;
import io.netty.handler.timeout.IdleStateHandler;

import java.util.concurrent.TimeUnit;

public class WebSocketServer {
    

    private static WebSocketServer wbss;

    private static final int READ_IDLE_TIME_OUT = 60; // 读超时
    private static final int WRITE_IDLE_TIME_OUT = 0;// 写超时
    private static final int ALL_IDLE_TIME_OUT = 0; // 所有超时

    public static WebSocketServer inst() {
    
        return wbss = new WebSocketServer();
    }

    public void run(int port) {
    
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        ServerBootstrap b = new ServerBootstrap();
        b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer <SocketChannel>() {
    
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {
    
                        ChannelPipeline pipeline = ch.pipeline();
                        // Netty自己的http解码器和编码器，报文级别 HTTP请求的解码和编码
                        pipeline.addLast(new HttpServerCodec());
                        // ChunkedWriteHandler 是用于大数据的分区传输
                        // 主要用于处理大数据流，比如一个1G大小的文件如果你直接传输肯定会撑暴jvm内存的;
                        // 增加之后就不用考虑这个问题了
                        pipeline.addLast(new ChunkedWriteHandler());
                        // HttpObjectAggregator 是完全的解析Http消息体请求用的
                        // 把多个消息转换为一个单一的完全FullHttpRequest或是FullHttpResponse，
                        // 原因是HTTP解码器会在每个HTTP消息中生成多个消息对象HttpRequest/HttpResponse,HttpContent,LastHttpContent
                        pipeline.addLast(new HttpObjectAggregator(64 * 1024));
                        // WebSocket数据压缩
                        pipeline.addLast(new WebSocketServerCompressionHandler());
                        // WebSocketServerProtocolHandler是配置websocket的监听地址/协议包长度限制
                        pipeline.addLast(new WebSocketServerProtocolHandler("/ws", null, true, 10 * 1024));

                        // 当连接在60秒内没有接收到消息时，就会触发一个 IdleStateEvent 事件，
                        // 此事件被 HeartbeatHandler 的 userEventTriggered 方法处理到
                        pipeline.addLast(
                                new IdleStateHandler(READ_IDLE_TIME_OUT, WRITE_IDLE_TIME_OUT, ALL_IDLE_TIME_OUT, TimeUnit.SECONDS));

                        // WebSocketServerHandler、TextWebSocketFrameHandler 是自定义逻辑处理器，
                        pipeline.addLast(new WebSocketTextHandler());
                    }
                });
        Channel ch = b.bind(port).syncUninterruptibly().channel();
        ch.closeFuture().syncUninterruptibly();

        // 返回与当前Java应用程序关联的运行时对象
        Runtime.getRuntime().addShutdownHook(new Thread() {
    
            @Override
            public void run() {
    
                SessionGroup.inst().shutdownGracefully();
                bossGroup.shutdownGracefully();
                workerGroup.shutdownGracefully();
            }
        });
    }
}

6.index.html

<!DOCTYPE HTML>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title>群聊天室</title>
    <style type="text/css">
        body {
    
            margin-right:50px;
            margin-left:50px;
        }
        .ddois {
    
            position: fixed;
            left: 120px;
            bottom: 30px;
        }
    </style>
</head>
<body>
群名：<input type="text" id="room" name="group" placeholder="请输入群">
<br /><br />
昵称：<input type="text" id="nick" name="name" placeholder="请输入昵称">
<br /><br />
<button type="button" onclick="enter()">进入聊天群</button>
<br /><br />
<div id="message"></div>
<br /><br />
<div class="ddois">
    <textarea name="send" id="text" rows="10" cols="30" placeholder="输入发送消息"></textarea>
    <br /><br />
    <button type="button" onclick="send()">发送</button>
</div>
<script type="text/javascript">
    var webSocket;

    if (window.WebSocket) {
    
        webSocket = new WebSocket("ws://localhost:8088/ws");
    } else {
    
        alert("抱歉，您的浏览器不支持WebSocket协议!");
    }

    //连通之后的回调事件
    webSocket.onopen = function() {
    
        console.log("已经连通了websocket");
// setMessageInnerHTML("已经连通了websocket");
    };
    //连接发生错误的回调方法
    webSocket.onerror = function(event){
    
        console.log("出错了");
// setMessageInnerHTML("连接失败");
    };

    //连接关闭的回调方法
    webSocket.onclose = function(){
    
        console.log("连接已关闭...");

    }

    //接收到消息的回调方法
    webSocket.onmessage = function(event){
    
        console.log("bbdds");
        var data = JSON.parse(event.data)
        var msg = data.msg;
        var nick = data.sendUser;
        switch(data.type){
    
            case 'init':
                console.log("mmll");
                break;
            case 'msg':
                console.log("bblld");
                setMessageInnerHTML(nick+": "+msg);
                break;
            default:
                break;
        }
    }
    function enter(){
    
        var map = new Map();
        var nick=document.getElementById('nick').value;
        var room=document.getElementById('room').value;
        map.set("type","init");
        map.set("nick",nick);
        console.log(room);
        map.set("room",room);
        var message = Map2Json(map);
        webSocket.send(message);
    }

    function send() {
    
        var msg = document.getElementById('text').value;
        var nick = document.getElementById('nick').value;
        console.log("1:"+msg);
        if (msg != null && msg != ""){
    
            var map = new Map();
            map.set("type","msg");
            map.set("msg",msg);
            var map2json=Map2Json(map);
            if (map2json.length < 8000){
    
                console.log("4:"+map2json);
                webSocket.send(map2json);
            }else {
    
                console.log("文本太长了，少写一点吧");
            }
        }
    }

    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
    
        document.getElementById("message").innerHTML += innerHTML + "<br/>";
    }

    function Map2Json(map) {
    
        var str = "{";
        map.forEach(function (value, key) {
    
            str += '"'+key+'"'+':'+ '"'+value+'",';
        })
        str = str.substring(0,str.length-1)
        str +="}";
        return str;
    }

</script>

</body>
</html>

二. 动态网页的信息爬取

1）对一个网页进行自动化测试。比如自动填充百度网页的查询关键字，完成自动搜索。

driver = webdriver.Chrome("E:\GoogleDownload\chromedriver_win32\chromedriver.exe")
# 名言所在网站
driver.get("http://quotes.toscrape.com/js/")
# 表头
csvHeaders = ['作者','名言']
# 所有数据
subjects = []
# 单个数据
subject=[]
# 获取所有含有quote的标签
res_list=driver.find_elements_by_class_name("quote")

# 分离出需要的内容
for tmp in res_list:
    subject.append(tmp.find_element_by_class_name("author").text)
    subject.append(tmp.find_element_by_class_name("text").text)
    print(subject)
    subjects.append(subject)
    subject=[]

2）爬取一个动态网页的数据，按附件要求实现代码。

3）爬取京东网站上的感兴趣书籍信息（如关键字“python编程”的前200本图书），并保存

driver = webdriver.Chrome("E:\GoogleDownload\chromedriver_win32\chromedriver.exe")
driver.set_window_size(1920,1080)
# 京东网站
driver.get("https://www.jd.com/")

# 输入需要查找的关键字
key=driver.find_element_by_id("key").send_keys("python编程")
time.sleep(1)

# 点击搜素按钮
button=driver.find_element_by_class_name("button").click()
time.sleep(1)

# 获取所有窗口
windows = driver.window_handles
# 切换到最新的窗口
driver.switch_to.window(windows[-1])
time.sleep(1)

# js语句
js = 'return document.body.scrollHeight'
# 获取body高度
max_height = driver.execute_script(js)
max_height=(int(max_height/1000))*1000
# 当前滚动条高度
tmp_height=1000
# 所有书籍的字典
res_dict={
    }

# 需要爬取的数量
num=200
while len(res_dict)<num:
    # 当切换网页后重新设置高度
    tmp_height = 1000
    while tmp_height < max_height:
        # 向下滑动
        js = "window.scrollBy(0,1000)"
        driver.execute_script(js)
        tmp_height += 1000

        # 书籍列表
        J_goodsList = driver.find_element_by_id("J_goodsList")
        ul = J_goodsList.find_element_by_tag_name("ul")
        # 所有书籍
        res_list = ul.find_elements_by_tag_name("li")
        # 把没有记录过的书籍加入字典
        for res in res_list:
            # 以书名为键,价格为值
            # 两种方式获取指定标签值
            res_dict[res.find_element_by_class_name('p-name').find_element_by_tag_name('em').text] \
                = res.find_element_by_xpath("//div[@class='p-price']//i").text
            if len(res_dict)==num:
                break
        time.sleep(2)
        if len(res_dict) == num:
            break
    # 下一页按钮所在父标签
    J_bottomPage=driver.find_element_by_id("J_bottomPage")
    # 下一页按钮
    next_button=J_bottomPage.find_element_by_class_name("pn-next").click()
    # 切换窗口
    windows = driver.window_handles
    driver.switch_to.window(windows[-1])
    time.sleep(3)


# 表头
csvHeaders = ['书名','价格']
# 所有书籍
csvRows=[]
# 书籍
row=[]

# 字典转列表
for key,value in res_dict.items():
    row.append(key)
    row.append(value)
    csvRows.append(row)
    row=[]
# 保存爬取结果
with open('./output/jd_books.csv', 'w', newline='') as file:
    fileWriter = csv.writer(file)
    fileWriter.writerow(csvHeaders)
    fileWriter.writerows(csvRows)

三.参考

读书笔记：《Netty进阶之路》——Netty服务端、Netty客户端、优雅关闭
Netty3学习笔记（一） — 传统IO与NIO比较
Java基于IO、NIO和Netty实现简单C/S聊天
springboot和netty整合的聊天室–群聊