【Socket网络编程】-UDP辅助TCP实现点到点传输Java

UDP搜索

服务器端

TCP口令

package constants;

/**
 * TCP不变的量
 * Created by 007 on 2020/7/8.
 */
public class TCPConstants {
    //服务器固化UDP接收端口
    public static int PORT_SERVER = 30401;

}

UDP口令

package constants;

/**
 * UDP不变的量
 * Created by 007 on 2020/7/8.
 */
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;

}

服务器端Server

package server;

import constants.TCPConstants;

import java.io.IOException;

/**
 * 服务器端
 * Created by 007 on 2020/7/8.
 */
public class Server {
    public static void main(String[] args){
        ServerProvider.start(TCPConstants.PORT_SERVER);
        try{
            System.in.read();
        }catch (IOException e){
            e.printStackTrace();
        }
        ServerProvider.stop();
    }

}

ServerProvider类

package server;

import clink.net.qiujuer.clink.utils.ByteUtils;
import constants.UDPConstants;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.nio.ByteBuffer;
import java.util.UUID;

/**
 * UDP服务器提供者
 * Created by 007 on 2020/7/8.
 */
public class ServerProvider {
    private static Provider PROVIDER_INSTANCE; //单例

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

    //单例模式
    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{
                //监听端口
                ds = new DatagramSocket(UDPConstants.PORT_SERVER);
                //接受消息的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 (IOException ignored) {
            } finally {
                close();
            }
        }

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

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

ByteUtils工具类

package clink.net.qiujuer.clink.utils;


/**
 * 字节工具
 * Created by 007 on 2020/7/9.
 */
public class ByteUtils {

    public static boolean startsWith(byte[] source, byte[] match) {
        return startsWith(source, 0, match);
    }

    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;
    }

    public static boolean equals(byte[] source,byte[] match){
        if (match.length != source.length){
            return false;
        }
        return startsWith(source,0,match);
    }

    public static void getBytes(byte[] source,int srcBegin,int srcEnd,
                                byte[] destination,int dstBegin){
        System.arraycopy(source,srcBegin,destination,dstBegin,srcEnd-srcBegin);
    }

    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;
    }

    public static byte[] subbytes(byte[] source,int srcBegin){
        return subbytes(source,srcBegin,source.length);
    }
}

客户端

客户端Client

package client;

import client.bean.ServerInfo;

/**
 * 客户端搜索
 * Created by 007 on 2020/7/8.
 */
public class Client {

    public static void main(String[] args){
        //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
        ServerInfo info = ClientSearcher.searchServer(10000);
        System.out.println("Server:"+info);
    }
}

ServerInfo类 ，服务器端信息

package client.bean;

/**
 *
 * Created by 007 on 2020/7/8.
 */
public class ServerInfo {
    private String sn;
    private int port;
    private String address;

    public ServerInfo(String sn, int port, String address) {
        this.sn = sn;
        this.port = port;
        this.address = address;
    }

    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 + '\'' +
                '}';
    }
}

ClientSearcher 类

package client;

import client.bean.ServerInfo;
import clink.net.qiujuer.clink.utils.ByteUtils;
import 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;

/**
 * 搜索服务器端
 * Created by 007 on 2020/7/8.
 */
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(sn, serverPort, ip);
                    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;
        }
    }
}

运行

启动服务器端Server

启动客户端Client

报错了，检查发现广播地址写成了255,255,255,255，应该是"255.255.255.255"。因为IPv4的地址一般是32位，每8位用.分隔。

修改为"255.255.255.255"，再运行。。


数据无效。。

检查过后没有发现问题，不知道为什么会数据无效，待解决。

更新：
检查了一天才发现问题，前面一直在找UDP的逻辑问题，几番检查不知道问题出现在哪里，然后今天早上想着会不会是工具类ByteUtils的问题，一看果然，写startsWith()函数时，最后应该返回true,写成了false,所以才是一直数据无效。

更改后运行:

client:

server:

终于运行成功啦。

点对点传输

rename ServerProvider 为 UDPProvider
rename ClientServer 为 UDPServer

新增 TCPServer类和TCPClient类

服务器端

TCPServer类

package server;

import client.Client;

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

/**
 * TCP服务器端
 * Created by 007 on 2020/7/11.
 */
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();
        }
    }


    public 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
    * */
    public static class ClientHandler extends Thread{
        private final Socket socket;
        private boolean flag = true;

        public 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 (IOException 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

TCPClient类

package client;

import client.bean.ServerInfo;
import server.Server;

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

/**
 * TCP客户端
 * Created by 007 on 2020/7/11.
 */
public class TCPClient {

    public static void linkWith(ServerInfo info) throws IOException {
        Socket socket = new Socket();

        //超时连接
        socket.setSoTimeout(3000);

        //链接本地
        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("服务器端信息："+socket.getInetAddress()+",P:"+socket.getPort());

        try{
            //发送数据
            todo(socket);
        }catch (IOException e){
            e.printStackTrace();
        }

        //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BufferReader
        InputStream inputStream = client.getInputStream();
        BufferedReader socketBufferReader = new BufferedReader(new InputStreamReader(inputStream));

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

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

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


}

运行

先server

再client

client输入数据

服务器端server

特别注意：
当重新启动服务器时，一定要将之前正在运行的服务器关闭。

数据发送与接收并行

多线程收发并行

TCP多线程收发协作

服务器端

package server;

import constants.TCPConstants;

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

/**
 * 服务器端
 * Created by 007 on 2020/7/8.
 */
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();
    }

}

读写分离

package server.handle;

import clink.net.qiujuer.clink.utils.CloseUtils;

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

/**
 * Created by 007 on 2020/7/12.
 */
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);//自己调用的话，自己关闭掉自己
    }

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

    //读取信息独立
    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");
                        //退出当前的客户端
                        ClientHandler.this.exitBySelf();
                        break;//退出客户端
                    }
                    //打印到屏幕上
                    System.out.println(str);
                } while (true);

            } catch (IOException 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);
        }
    }

    //发送数据，线程等待不好操作不用extends Thread,换为构建线程池-单例
    class ClientWriteHandler {

        private boolean done = false;
        private final PrintStream printStream;
        private final ExecutorService executorServer; //线程池

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


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

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

            }
        }
    }
}

关闭工具类

package clink.net.qiujuer.clink.utils;

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

/**
 * 关闭工具
 * Created by 007 on 2020/7/12.
 */
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();
            }
        }
    }
}

客户端

读写分离

package client;

import client.bean.ServerInfo;
import clink.net.qiujuer.clink.utils.CloseUtils;
import server.Server;
import server.handle.ClientHandler;

import java.io.*;
import java.net.*;

/**
 * TCP客户端
 * Created by 007 on 2020/7/11.
 */
public class TCPClient {

    public static void linkWith(ServerInfo info) throws IOException {
        Socket socket = new Socket();

        //超时连接
        socket.setSoTimeout(3000);

        //链接本地
        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("服务器端信息：" + socket.getInetAddress() + ",P:" + socket.getPort());

        try {
            ReadHandler readhandler = new ReadHandler(socket.getInputStream());
            readhandler.start();
            
            //发送数据
            write(socket);
            
            //读取退出操作
            readhandler.exit();
        } catch (IOException e) {
            System.out.println("异常关闭"+e.getMessage());
        }

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

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

        socketPrintStream.close();
    }

    //读取信息独立
    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 {                        //可能出现超时异常
                        //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;//退出客户端
                    }
                    //打印到屏幕上
                    System.out.println(str);
                } while (true);

            } catch (IOException 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);
        }
    }


}

运行

本文地址：https://blog.csdn.net/weixin_44110891/article/details/107226021