【网络编程】UDP辅助TCP实现点对点传输

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本文链接： https://blog.csdn.net/qq_42322103/article/details/97548054

概述

场景： 局域网中，不知道服务器的IP地址，仅仅知道公共的UPD端口，这里需要用到UDP进行广播，收到服务器的回送信息，确定服务器的IP地址 然后建立TCP的连接。

UDP搜索IP与端口

• 构建基础口令消息
• 局域网广播口令消息（指定端口）
• 接收指定端口回送消息（得到客户端IP、Port）

UDP搜索取消实现

• 异步线程接收回送消息
• 异步线程等待完成（定时）
• 关闭等待-终止线程等待

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$内容实在是太多了 ,等我之后慢慢添加内容 完善它叭$

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实现

UDP搜索

服务器端

构建基础口令消息：
UDP口令

public class UDPConstants {
    // 公用头部
    public static byte[] HEADER = new byte[]{7, 7, 7, 7, 7, 7, 7, 7};
    // 服务器固化UDP接收端口
    public static int PORT_SERVER = 30201;
    // 客户端回送端口
    public static int PORT_CLIENT_RESPONSE = 30202;
}

TCP口令

public class TCPConstants {
    // 服务器固化UDP接收端口
    public static int PORT_SERVER = 30401;
}

服务器端代码

import constants.TCPConstants;

import java.io.IOException;

public class Server {
    public static void main(String[] args) {
        ServerProvider.start(TCPConstants.PORT_SERVER);  

        try {
            //noinspection ResultOfMethodCallIgnored
            System.in.read();
        } catch (IOException e) {
            e.printStackTrace();
        }

        ServerProvider.stop();
    }
}

ServerProvider类
Provider 是内部类

import com.company.utils.ByteUtils;
import com.company.constants.UDPConstants;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.nio.ByteBuffer;
import java.util.UUID;

class ServerProvider {
    private static Provider PROVIDER_INSTANCE;  //Provider是内部类

    static void start(int port) {
        stop();
        String sn = UUID.randomUUID().toString();
        Provider provider = new Provider(sn, port);
        provider.start();
        PROVIDER_INSTANCE = provider;
    }

    static void stop() {
        if (PROVIDER_INSTANCE != null) {
            PROVIDER_INSTANCE.exit();
            PROVIDER_INSTANCE = null;
        }
    }

    private static class Provider extends Thread {
        private final byte[] sn;
        private final int port;
        private boolean done = false;
        private DatagramSocket ds = null;
        // 存储消息的Buffer
        final byte[] buffer = new byte[128];

        Provider(String sn, int port) {
            super();
            this.sn = sn.getBytes();
            this.port = port;
        }

        @Override
        public void run() {
            super.run();

            System.out.println("UDPProvider Started.");

            try {
                // 监听20000 端口
                ds = new DatagramSocket(UDPConstants.PORT_SERVER);
                // 接收消息的Packet
                DatagramPacket receivePack = new DatagramPacket(buffer, buffer.length);

                while (!done) {

                    // 接收
                    ds.receive(receivePack);

                    // 打印接收到的信息与发送者的信息
                    // 发送者的IP地址
                    String clientIp = receivePack.getAddress().getHostAddress();
                    int clientPort = receivePack.getPort();
                    int clientDataLen = receivePack.getLength();
                    byte[] clientData = receivePack.getData();
                    boolean isValid = clientDataLen >= (UDPConstants.HEADER.length + 2 + 4)
                            && ByteUtils.startsWith(clientData, UDPConstants.HEADER);

                    System.out.println("ServerProvider receive form ip:" + clientIp
                            + "\tport:" + clientPort + "\tdataValid:" + isValid);

                    if (!isValid) {
                        // 无效继续
                        continue;
                    }

                    // 解析命令与回送端口
                    int index = UDPConstants.HEADER.length;
                    short cmd = (short) ((clientData[index++] << 8) | (clientData[index++] & 0xff));
                    int responsePort = (((clientData[index++]) << 24) |
                            ((clientData[index++] & 0xff) << 16) |
                            ((clientData[index++] & 0xff) << 8) |
                            ((clientData[index] & 0xff)));

                    // 判断合法性
                    if (cmd == 1 && responsePort > 0) {
                        // 构建一份回送数据
                        ByteBuffer byteBuffer = ByteBuffer.wrap(buffer);
                        byteBuffer.put(UDPConstants.HEADER);
                        byteBuffer.putShort((short) 2);
                        byteBuffer.putInt(port);
                        byteBuffer.put(sn);
                        int len = byteBuffer.position();
                        // 直接根据发送者构建一份回送信息
                        DatagramPacket responsePacket = new DatagramPacket(buffer,
                                len,
                                receivePack.getAddress(),
                                responsePort);
                        ds.send(responsePacket);
                        System.out.println("ServerProvider response to:" + clientIp + "\tport:" + responsePort + "\tdataLen:" + len);
                    } else {
                        System.out.println("ServerProvider receive cmd nonsupport; cmd:" + cmd + "\tport:" + port);
                    }
                }
            } catch (Exception ignored) {
            } finally {
                close();
            }

            // 完成
            System.out.println("UDPProvider Finished.");
        }

        private void close() {
            if (ds != null) {
                ds.close();
                ds = null;
            }
        }

        /**
         * 提供结束
         */
        void exit() {
            done = true;
            close();
        }
    }
}

客户端

启动入口

import com.company.client.bean.ServerInfo;

public class Client {
    public static void main(String[] args) {
        ServerInfo info = ClientSearcher.searchServer(10000);  //客户端启动搜索 搜索超时时间是10秒 找到后存储服务器端信息
        System.out.println("Server:" + info);
    }
}

ServerInfo类 是服务器端信息

public class ServerInfo {
    private String sn;  //服务器端发送的数据
    private int port;    //服务器端的端口
    private String address;  //服务器端的地址

	//构造函数 getter setter方法 与toString打印信息
    public ServerInfo(int port, String ip, String sn) {
        this.port = port;
        this.address = ip;
        this.sn = sn;
    }

    public String getSn() {
        return sn;
    }

    public void setSn(String sn) {
        this.sn = sn;
    }

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "ServerInfo{" +
                "sn='" + sn + '\'' +
                ", port=" + port +
                ", address='" + address + '\'' +
                '}';
    }
}

客户端核心功能实现 ClientSearcher 类

import com.company.client.bean.ServerInfo;
import com.company.utils.ByteUtils;
import com.company.constants.UDPConstants;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

public class ClientSearcher {
    private static final int LISTEN_PORT = UDPConstants.PORT_CLIENT_RESPONSE;

    public static ServerInfo searchServer(int timeout) {  //传入的参数是超时时间
        System.out.println("UDPSearcher Started.");

        // 成功收到回送的栅栏
        CountDownLatch receiveLatch = new CountDownLatch(1);
        //CountDownLatch是一个同步工具类，它允许一个或多个线程一直等待，直到其他线程执行完后再执行。
        //例如，应用程序的主线程希望在负责启动框架服务的线程已经启动所有框架服务之后执行。
        Listener listener = null;   //构造监听者  监听回送信息 Listener为内部类
        try {
            listener = listen(receiveLatch);  //初始实例化监听类  
            sendBroadcast();  //广播消息
            receiveLatch.await(timeout, TimeUnit.MILLISECONDS);   
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 完成
        System.out.println("UDPSearcher Finished.");
        if (listener == null) {
            return null;
        }
        List<ServerInfo> devices = listener.getServerAndClose();
        if (devices.size() > 0) {
            return devices.get(0);
        }
        return null;
    }

    private static Listener listen(CountDownLatch receiveLatch) throws InterruptedException {
        System.out.println("UDPSearcher start listen.");
        CountDownLatch startDownLatch = new CountDownLatch(1);
        Listener listener = new Listener(LISTEN_PORT, startDownLatch, receiveLatch);
        listener.start();
        startDownLatch.await();
        return listener;
    }

    private static void sendBroadcast() throws IOException {
        System.out.println("UDPSearcher sendBroadcast started.");

        // 作为搜索方，让系统自动分配端口
        DatagramSocket ds = new DatagramSocket();

        // 构建一份请求数据
        ByteBuffer byteBuffer = ByteBuffer.allocate(128);
        // 头部
        byteBuffer.put(UDPConstants.HEADER);
        // CMD命名
        byteBuffer.putShort((short) 1);
        // 回送端口信息
        byteBuffer.putInt(LISTEN_PORT);
        // 直接构建packet
        DatagramPacket requestPacket = new DatagramPacket(byteBuffer.array(),
                byteBuffer.position() + 1);
        // 广播地址
        requestPacket.setAddress(InetAddress.getByName("255.255.255.255"));
        // 设置服务器端口
        requestPacket.setPort(UDPConstants.PORT_SERVER);

        // 发送
        ds.send(requestPacket);
        ds.close();

        // 完成
        System.out.println("UDPSearcher sendBroadcast finished.");
    }

    private static class Listener extends Thread {
        private final int listenPort;    
        private final CountDownLatch startDownLatch;
        private final CountDownLatch receiveDownLatch;
        private final List<ServerInfo> serverInfoList = new ArrayList<>();  //所有ServerInfo的列表
        private final byte[] buffer = new byte[128]; 
        private final int minLen = UDPConstants.HEADER.length + 2 + 4;  //UDP口令长度 + 2个字节的命令长度+服务器回送的TCP对应的端口号
        private boolean done = false;  //是否已经完成
        private DatagramSocket ds = null;

        private Listener(int listenPort, CountDownLatch startDownLatch, CountDownLatch receiveDownLatch) {
            super();
            this.listenPort = listenPort;
            this.startDownLatch = startDownLatch;
            this.receiveDownLatch = receiveDownLatch;
        }

        @Override
        public void run() {
            super.run();

            // 通知已启动
            startDownLatch.countDown();
            try {
                // 监听回送端口
                ds = new DatagramSocket(listenPort);
                // 构建接收实体
                DatagramPacket receivePack = new DatagramPacket(buffer, buffer.length);

                while (!done) {
                    // 接收
                    ds.receive(receivePack);

                    // 打印接收到的信息与发送者的信息
                    // 发送者的IP地址
                    String ip = receivePack.getAddress().getHostAddress();
                    int port = receivePack.getPort();
                    int dataLen = receivePack.getLength();
                    byte[] data = receivePack.getData();
                    boolean isValid = dataLen >= minLen
                            && ByteUtils.startsWith(data, UDPConstants.HEADER);

                    System.out.println("UDPSearcher receive form ip:" + ip
                            + "\tport:" + port + "\tdataValid:" + isValid);

                    if (!isValid) {
                        // 无效继续
                        continue;
                    }

                    ByteBuffer byteBuffer = ByteBuffer.wrap(buffer, UDPConstants.HEADER.length, dataLen);
                    final short cmd = byteBuffer.getShort();
                    final int serverPort = byteBuffer.getInt();
                    if (cmd != 2 || serverPort <= 0) {
                        System.out.println("UDPSearcher receive cmd:" + cmd + "\tserverPort:" + serverPort);
                        continue;
                    }

                    String sn = new String(buffer, minLen, dataLen - minLen);
                    ServerInfo info = new ServerInfo(serverPort, ip, sn);
                    serverInfoList.add(info);
                    // 成功接收到一份
                    receiveDownLatch.countDown();
                }
            } catch (Exception ignored) {
            } finally {
                close();
            }
            System.out.println("UDPSearcher listener finished.");
        }

        private void close() {
            if (ds != null) {
                ds.close();
                ds = null;
            }
        }

        List<ServerInfo> getServerAndClose() {
            done = true; //循环推出
            close();
            return serverInfoList;
        }
    }
}

上面 用到的工具类ClientSearcher 类

public class ByteUtils {
    /**
     * Does this byte array begin with match array content?
     *
     * @param source Byte array to examine
     * @param match  Byte array to locate in <code>source</code>
     * @return true If the starting bytes are equal
     */
    public static boolean startsWith(byte[] source, byte[] match) {
        return startsWith(source, 0, match);
    }

    /**
     * Does this byte array begin with match array content?
     *
     * @param source Byte array to examine
     * @param offset An offset into the <code>source</code> array
     * @param match  Byte array to locate in <code>source</code>
     * @return true If the starting bytes are equal
     */
    public static boolean startsWith(byte[] source, int offset, byte[] match) {

        if (match.length > (source.length - offset)) {
            return false;
        }

        for (int i = 0; i < match.length; i++) {
            if (source[offset + i] != match[i]) {
                return false;
            }
        }
        return true;
    }

    /**
     * Does the source array equal the match array?
     *
     * @param source Byte array to examine
     * @param match  Byte array to locate in <code>source</code>
     * @return true If the two arrays are equal
     */
    public static boolean equals(byte[] source, byte[] match) {

        if (match.length != source.length) {
            return false;
        }
        return startsWith(source, 0, match);
    }

    /**
     * Copies bytes from the source byte array to the destination array
     *
     * @param source      The source array
     * @param srcBegin    Index of the first source byte to copy
     * @param srcEnd      Index after the last source byte to copy
     * @param destination The destination array
     * @param dstBegin    The starting offset in the destination array
     */
    public static void getBytes(byte[] source, int srcBegin, int srcEnd, byte[] destination,
                                int dstBegin) {
        System.arraycopy(source, srcBegin, destination, dstBegin, srcEnd - srcBegin);
    }

    /**
     * Return a new byte array containing a sub-portion of the source array
     *
     * @param srcBegin The beginning index (inclusive)
     * @param srcEnd   The ending index (exclusive)
     * @return The new, populated byte array
     */
    public static byte[] subbytes(byte[] source, int srcBegin, int srcEnd) {
        byte destination[];

        destination = new byte[srcEnd - srcBegin];
        getBytes(source, srcBegin, srcEnd, destination, 0);

        return destination;
    }

    /**
     * Return a new byte array containing a sub-portion of the source array
     *
     * @param srcBegin The beginning index (inclusive)
     * @return The new, populated byte array
     */
    public static byte[] subbytes(byte[] source, int srcBegin) {
        return subbytes(source, srcBegin, source.length);
    }
}

启动Server端

启动Client端

Server端信息:

实现点对点传输实现

根据UDP信息建立TCP链接

服务器端

import com.company.constants.TCPConstants;

import java.io.IOException;

public class Server {
    public static void main(String[] args) {
    	//添加内容****************************************
        TCPServer tcpServer = new TCPServer(TCPConstants.PORT_SERVER);
        boolean isSucceed = tcpServer.start();
        if (!isSucceed) {
            System.out.println("Start TCP server failed!");
            return;
        }
		//添加内容****************************************
        UDPProvider.start(TCPConstants.PORT_SERVER);

        try {
            //noinspection ResultOfMethodCallIgnored
            System.in.read();
        } catch (IOException e) {
            e.printStackTrace();
        }

        UDPProvider.stop();
        tcpServer.stop();
    }
}

TCPServer类 相比之前多的内容

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;

public class TCPServer {
    private final int port;
    private ClientListener mListener;

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

    public boolean start() {
        try {
            ClientListener listener = new ClientListener(port);
            mListener = listener;
            listener.start();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    public void stop() {
        if (mListener != null) {
            mListener.exit();
        }
    }

    private static class ClientListener extends Thread {
        private ServerSocket server;
        private boolean done = false;

        private ClientListener(int port) throws IOException {
            server = new ServerSocket(port);
            System.out.println("服务器信息：" + server.getInetAddress() + " P:" + server.getLocalPort());
        }

        @Override
        public void run() {
            super.run();

            System.out.println("服务器准备就绪～");
            // 等待客户端连接
            do {
                // 得到客户端
                Socket client;
                try {
                    client = server.accept();
                } catch (IOException e) {
                    continue;
                }
                // 客户端构建异步线程
                ClientHandler clientHandler = new ClientHandler(client);
                // 启动线程
                clientHandler.start();
            } while (!done);

            System.out.println("服务器已关闭！");
        }

        void exit() {
            done = true;
            try {
                server.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 客户端消息处理
     */
    private static class ClientHandler extends Thread {
        private Socket socket;
        private boolean flag = true;

        ClientHandler(Socket socket) {
            this.socket = socket;
        }

        @Override
        public void run() {
            super.run();
            System.out.println("新客户端连接：" + socket.getInetAddress() +
                    " P:" + socket.getPort());

            try {
                // 得到打印流，用于数据输出；服务器回送数据使用
                PrintStream socketOutput = new PrintStream(socket.getOutputStream());
                // 得到输入流，用于接收数据
                BufferedReader socketInput = new BufferedReader(new InputStreamReader(
                        socket.getInputStream()));

                do {
                    // 客户端拿到一条数据
                    String str = socketInput.readLine();
                    if ("bye".equalsIgnoreCase(str)) {
                        flag = false;
                        // 回送
                        socketOutput.println("bye");
                    } else {
                        // 打印到屏幕。并回送数据长度
                        System.out.println(str);
                        socketOutput.println("回送：" + str.length());
                    }

                } while (flag);

                socketInput.close();
                socketOutput.close();

            } catch (Exception e) {
                System.out.println("连接异常断开");
            } finally {
                // 连接关闭
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            System.out.println("客户端已退出：" + socket.getInetAddress() +
                    " P:" + socket.getPort());

        }
    }
}

客户端

添加

import com.company.ServerInfo;

import java.io.*;
import java.net.Inet4Address;
import java.net.InetSocketAddress;
import java.net.Socket;

public class TCPClient {
    public static void linkWith(ServerInfo info) throws IOException {
        Socket socket = new Socket();
        // 超时时间
        socket.setSoTimeout(3000);

        // 连接本地，端口2000；超时时间3000ms
        socket.connect(new InetSocketAddress(Inet4Address.getByName(info.getAddress()), info.getPort()), 3000);

        System.out.println("已发起服务器连接，并进入后续流程～");
        System.out.println("客户端信息：" + socket.getLocalAddress() + " P:" + socket.getLocalPort());
        System.out.println("服务器信息：" + socket.getInetAddress() + " P:" + socket.getPort());

        try {
            // 发送接收数据
            todo(socket);
        } catch (Exception e) {
            System.out.println("异常关闭");
        }

        // 释放资源
        socket.close();
        System.out.println("客户端已退出～");

    }

    private static void todo(Socket client) throws IOException {
        // 构建键盘输入流
        InputStream in = System.in;
        BufferedReader input = new BufferedReader(new InputStreamReader(in));


        // 得到Socket输出流，并转换为打印流
        OutputStream outputStream = client.getOutputStream();
        PrintStream socketPrintStream = new PrintStream(outputStream);


        // 得到Socket输入流，并转换为BufferedReader
        InputStream inputStream = client.getInputStream();
        BufferedReader socketBufferedReader = new BufferedReader(new InputStreamReader(inputStream));

        boolean flag = true;
        do {
            // 键盘读取一行
            String str = input.readLine();
            // 发送到服务器
            socketPrintStream.println(str);


            // 从服务器读取一行
            String echo = socketBufferedReader.readLine();
            if ("bye".equalsIgnoreCase(echo)) {
                flag = false;
            } else {
                System.out.println(echo);
            }
        } while (flag);

        // 资源释放
        socketPrintStream.close();
        socketBufferedReader.close();

    }
}

启动服务器端

启动客户端:

服务器端信息:

---

客户端给服务器端发送消息 并且就收 服务器端把消息的长度回送回来的信息

服务器端收到客户端的消息 打印在自己的控制台,并回送消息的长度

数据发送与接收并行

主要内容:
多线程收发并行
TCP多线程收发协作

服务器端

改造Server类

import com.company.constants.TCPConstants;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Server {
    public static void main(String[] args) throws IOException {
        TCPServer tcpServer = new TCPServer(TCPConstants.PORT_SERVER);
        boolean isSucceed = tcpServer.start();
        if (!isSucceed) {
            System.out.println("Start TCP server failed!");
            return;
        }

        UDPProvider.start(TCPConstants.PORT_SERVER);

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        String str;
        do {
            str = bufferedReader.readLine();
            tcpServer.broadcast(str);
        } while (!"00bye00".equalsIgnoreCase(str));

        UDPProvider.stop();
        tcpServer.stop();
    }
}

添加一个类 ClientHandler类
客户端的处理类

import com.company.utils.CloseUtils;

import java.io.*;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ClientHandler {
    private final Socket socket;
    private final ClientReadHandler readHandler;
    private final ClientWriteHandler writeHandler;
    private final CloseNotify closeNotify;

    public ClientHandler(Socket socket, CloseNotify closeNotify) throws IOException {
        this.socket = socket;
        this.readHandler = new ClientReadHandler(socket.getInputStream());
        this.writeHandler = new ClientWriteHandler(socket.getOutputStream());
        this.closeNotify = closeNotify;
        System.out.println("新客户端连接：" + socket.getInetAddress() +
                " P:" + socket.getPort());
    }

    public void exit() {
        readHandler.exit();
        writeHandler.exit();
        CloseUtils.close(socket);
        System.out.println("客户端已退出：" + socket.getInetAddress() +
                " P:" + socket.getPort());
    }

    public void send(String str) {
        writeHandler.send(str);
    }

    public void readToPrint() {
        readHandler.start();
    }

    private void exitBySelf() {
        exit();
        closeNotify.onSelfClosed(this);
    }

    public interface CloseNotify {
        void onSelfClosed(ClientHandler handler);
    }

    class ClientReadHandler extends Thread {
        private boolean done = false;
        private final InputStream inputStream;

        ClientReadHandler(InputStream inputStream) {
            this.inputStream = inputStream;
        }

        @Override
        public void run() {
            super.run();
            try {
                // 得到输入流，用于接收数据
                BufferedReader socketInput = new BufferedReader(new InputStreamReader(inputStream));

                do {
                    // 客户端拿到一条数据
                    String str = socketInput.readLine();
                    if (str == null) {
                        System.out.println("客户端已无法读取数据！");
                        // 退出当前客户端
                        ClientHandler.this.exitBySelf();
                        break;
                    }
                    // 打印到屏幕
                    System.out.println(str);
                } while (!done);
            } catch (Exception e) {
                if (!done) {
                    System.out.println("连接异常断开");
                    ClientHandler.this.exitBySelf();
                }
            } finally {
                // 连接关闭
                CloseUtils.close(inputStream);
            }
        }

        void exit() {
            done = true;
            CloseUtils.close(inputStream);
        }
    }

    class ClientWriteHandler {
        private boolean done = false;
        private final PrintStream printStream;
        private final ExecutorService executorService;

        ClientWriteHandler(OutputStream outputStream) {
            this.printStream = new PrintStream(outputStream);
            this.executorService = Executors.newSingleThreadExecutor();
        }

        void exit() {
            done = true;
            CloseUtils.close(printStream);
            executorService.shutdownNow();
        }

        void send(String str) {
            executorService.execute(new WriteRunnable(str));
        }

        class WriteRunnable implements Runnable {
            private final String msg;

            WriteRunnable(String msg) {
                this.msg = msg;
            }

            @Override
            public void run() {
                if (ClientWriteHandler.this.done) {
                    return;
                }

                try {
                    ClientWriteHandler.this.printStream.println(msg);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

该类用到的工具类CloseUtils

import java.io.Closeable;
import java.io.IOException;

public class CloseUtils {
    public static void close(Closeable... closeables) {
        if (closeables == null) {
            return;
        }
        for (Closeable closeable : closeables) {
            try {
                closeable.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

改动 TCPServer

import server.handle.ClientHandler;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class TCPServer {
    private final int port;
    private ClientListener mListener;
    private List<ClientHandler> clientHandlerList = new ArrayList<>();

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

    public boolean start() {
        try {
            ClientListener listener = new ClientListener(port);
            mListener = listener;
            listener.start();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    public void stop() {
        if (mListener != null) {
            mListener.exit();
        }

        for (ClientHandler clientHandler : clientHandlerList) {
            clientHandler.exit();
        }

        clientHandlerList.clear();
    }

    public void broadcast(String str) {
        for (ClientHandler clientHandler : clientHandlerList) {
            clientHandler.send(str);
        }
    }

    private class ClientListener extends Thread {
        private ServerSocket server;
        private boolean done = false;

        private ClientListener(int port) throws IOException {
            server = new ServerSocket(port);
            System.out.println("服务器信息：" + server.getInetAddress() + " P:" + server.getLocalPort());
        }

        @Override
        public void run() {
            super.run();

            System.out.println("服务器准备就绪～");
            // 等待客户端连接
            do {
                // 得到客户端
                Socket client;
                try {
                    client = server.accept();
                } catch (IOException e) {
                    continue;
                }
                try {
                    // 客户端构建异步线程
                    ClientHandler clientHandler = new ClientHandler(client,
                            handler -> clientHandlerList.remove(handler));
                    // 读取数据并打印
                    clientHandler.readToPrint();
                    clientHandlerList.add(clientHandler);
                } catch (IOException e) {
                    e.printStackTrace();
                    System.out.println("客户端连接异常：" + e.getMessage());
                }
            } while (!done);

            System.out.println("服务器已关闭！");
        }

        void exit() {
            done = true;
            try {
                server.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

客户端部分

TCPClient的改动

import com.company.client.bean.ServerInfo;
import com.company.utils.CloseUtils;

import java.io.*;
import java.net.Inet4Address;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketTimeoutException;

public class TCPClient {
    public static void linkWith(ServerInfo info) throws IOException {
        Socket socket = new Socket();
        // 超时时间
        socket.setSoTimeout(3000);

        // 连接本地，端口2000；超时时间3000ms
        socket.connect(new InetSocketAddress(Inet4Address.getByName(info.getAddress()), info.getPort()), 3000);

        System.out.println("已发起服务器连接，并进入后续流程～");
        System.out.println("客户端信息：" + socket.getLocalAddress() + " P:" + socket.getLocalPort());
        System.out.println("服务器信息：" + socket.getInetAddress() + " P:" + socket.getPort());

        try {
            ReadHandler readHandler = new ReadHandler(socket.getInputStream());
            readHandler.start();

            // 发送接收数据
            write(socket);

            // 退出操作
            readHandler.exit();
        } catch (Exception e) {
            System.out.println("异常关闭");
        }

        // 释放资源
        socket.close();
        System.out.println("客户端已退出～");
    }

    private static void write(Socket client) throws IOException {
        // 构建键盘输入流
        InputStream in = System.in;
        BufferedReader input = new BufferedReader(new InputStreamReader(in));

        // 得到Socket输出流，并转换为打印流
        OutputStream outputStream = client.getOutputStream();
        PrintStream socketPrintStream = new PrintStream(outputStream);

        do {
            // 键盘读取一行
            String str = input.readLine();
            // 发送到服务器
            socketPrintStream.println(str);

            if ("00bye00".equalsIgnoreCase(str)) {
                break;
            }
        } while (true);

        // 资源释放
        socketPrintStream.close();
    }

    static class ReadHandler extends Thread {
        private boolean done = false;
        private final InputStream inputStream;

        ReadHandler(InputStream inputStream) {
            this.inputStream = inputStream;
        }

        @Override
        public void run() {
            super.run();
            try {
                // 得到输入流，用于接收数据
                BufferedReader socketInput = new BufferedReader(new InputStreamReader(inputStream));

                do {
                    String str;
                    try {
                        // 客户端拿到一条数据
                        str = socketInput.readLine();
                    } catch (SocketTimeoutException e) {
                        continue;
                    }
                    if (str == null) {
                        System.out.println("连接已关闭，无法读取数据！");
                        break;
                    }
                    // 打印到屏幕
                    System.out.println(str);
                } while (!done);
            } catch (Exception e) {
                if (!done) {
                    System.out.println("连接异常断开：" + e.getMessage());
                }
            } finally {
                // 连接关闭
                CloseUtils.close(inputStream);
            }
        }

        void exit() {
            done = true;
            CloseUtils.close(inputStream);
        }
    }
}

启动服务器端

启动客户端

服务器端信息

客户端与服务器你一句 我一句