java长连接的实现方式,附上代码实现

Java长连接的实现方式有很多种，以下是其中一种基于Socket的实现方式：

服务端代码实现：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        try {
            // 创建ServerSocket对象，绑定监听端口
            serverSocket = new ServerSocket(8888);
            System.out.println("服务器已启动，等待客户端连接...");
            while (true) {
                // 等待客户端连接，accept()方法会阻塞当前线程
                Socket socket = serverSocket.accept();
                System.out.println("客户端连接成功！" + socket.getInetAddress() + ":" + socket.getPort());
                // 开启线程处理客户端请求
                new Thread(new Handler(socket)).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭ServerSocket对象
            if (serverSocket != null) {
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    // 处理客户端请求的线程
    static class Handler implements Runnable {
        private Socket socket;

        public Handler(Socket socket) {
            this.socket = socket;
        }

        @Override
        public void run() {
            BufferedReader reader = null;
            PrintWriter writer = null;
            try {
                // 获取输入流
                reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                // 获取输出流
                writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()), true);
                String message;
                while ((message = reader.readLine()) != null) {
                    // 处理客户端请求
                    System.out.println("收到客户端消息：" + message);
                    writer.println("服务器已收到消息：" + message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                // 关闭流和Socket对象
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (writer != null) {
                    writer.close();
                }
                if (socket != null) {
                    try {
                        socket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
}

客户端代码实现：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class Client {
    public static void main(String[] args) {
        Socket socket = null;
        BufferedReader reader = null;
        PrintWriter writer = null;
        try {
            // 创建Socket对象，指定服务器地址和端口
            socket = new Socket("127.0.0.1", 8888);
            System.out.println("连接服务器成功！");
            // 获取输入流
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            // 获取输出流
            writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()), true);
            Scanner scanner = new Scanner(System.in);
            while (true) {
                System.out.print("请输入消息：");
                String message = scanner.nextLine();
                // 发送消息给服务器
                writer.println(message);
                // 接收服务器响应
                String response = reader.readLine();
                System.out.println("收到服务器消息：" + response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭流和Socket对象
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (writer != null) {
                writer.close();
            }
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

以上代码实现了一个简单的长连接示例，当客户端连接到服务端后，可以发送消息给服务端并接收服务端的响应。服务端会开启一个新的线程处理客户端请求，以实现多客户端同时连接的效果。