如何用Java实现Socket粘包处理 Java分包与重组技术讲解

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;

public class SocketPacketHandler {

    // 客户端发送消息的示例
    public static void sendMessage(Socket socket, String message) throws IOException {
        DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
        byte[] data = message.getBytes(StandardCharsets.UTF_8);
        dos.writeInt(data.length); // 先发送数据长度 (4字节)
        dos.write(data);          // 再发送实际数据
        dos.flush();
        System.out.println("客户端发送: [" + message + "] (长度: " + data.length + ")");
    }

    // 服务器端接收并重组消息的示例
    public static String receiveMessage(Socket socket) throws IOException {
        DataInputStream dis = new DataInputStream(socket.getInputStream());
        int length = dis.readInt(); // 先读取数据长度
        byte[] data = new byte[length];
        int bytesRead = 0;
        // 循环读取，直到读满一个完整的包
        while (bytesRead < length) {
            int result = dis.read(data, bytesRead, length - bytesRead);
            if (result == -1) { // 流结束，客户端可能已断开
                throw new EOFException("客户端已断开连接或流结束.");
            }
            bytesRead += result;
        }
        String receivedMessage = new String(data, StandardCharsets.UTF_8);
        System.out.println("服务器接收: [" + receivedMessage + "] (长度: " + length + ")");
        return receivedMessage;
    }

    public static void main(String[] args) {
        // 模拟服务器端
        new Thread(() -> {
            try (ServerSocket serverSocket = new ServerSocket(8080)) {
                System.out.println("服务器启动，等待客户端连接...");
                try (Socket clientSocket = serverSocket.accept()) {
                    System.out.println("客户端连接成功: " + clientSocket.getRemoteSocketAddress());
                    while (true) {
                        try {
                            receiveMessage(clientSocket);
                            // 模拟服务器处理完一个包后，可能继续发送响应
                            // sendMessage(clientSocket, "服务器收到: " + receivedMsg);
                        } catch (EOFException e) {
                            System.out.println(e.getMessage());
                            break; // 客户端关闭，退出循环
                        } catch (IOException e) {
                            System.err.println("服务器读取错误: " + e.getMessage());
                            break;
                        }
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }).start();

        // 模拟客户端
        try {
            Thread.sleep(1000); // 等待服务器启动
            try (Socket socket = new Socket("localhost", 8080)) {
                sendMessage(socket, "Hello, Socket!");
                Thread.sleep(100); // 模拟间隔
                sendMessage(socket, "This is a second message.");
                Thread.sleep(100);
                sendMessage(socket, "And a third, perhaps a bit longer to test splitting.");
            }
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}