用socket实现一个即时通讯程序 要求实现私聊 群聊 发送文件功能 c/c++实现

以下是一个简单的 C++ 实现的即时通讯程序，包含私聊、群聊和发送文件功能，使用了 socket 编程和多线程技术。

#include <iostream>
#include <string>
#include <vector>
#include <thread>
#include <mutex>
#include <fstream>
#include <winsock2.h>

using namespace std;

const int MAX_CLIENTS = 10;
const int BUFFER_SIZE = 1024;

struct Client {
    SOCKET socket;
    string name;
};

vector<Client> clients;
mutex mtx;

void broadcast(string message, SOCKET sender = INVALID_SOCKET) {
    mtx.lock();
    for (auto& client : clients) {
        if (client.socket != sender) {
            send(client.socket, message.c_str(), message.size() + 1, 0);
        }
    }
    mtx.unlock();
}

void send_file(SOCKET receiver, string file_path) {
    ifstream file(file_path, ios::binary);
    if (!file) {
        cerr << "Failed to open file: " << file_path << endl;
        return;
    }
    file.seekg(0, ios::end);
    int file_size = file.tellg();
    char* buffer = new char[file_size];
    file.seekg(0, ios::beg);
    file.read(buffer, file_size);
    file.close();
    send(receiver, (char*)&file_size, sizeof(file_size), 0);
    send(receiver, buffer, file_size, 0);
    delete[] buffer;
}

void handle_client(SOCKET client_socket) {
    char buffer[BUFFER_SIZE];
    int bytes_received;
    string name;
    while (true) {
        bytes_received = recv(client_socket, buffer, BUFFER_SIZE, 0);
        if (bytes_received == SOCKET_ERROR || bytes_received == 0) {
            cerr << "Client disconnected." << endl;
            break;
        }
        string message(buffer, bytes_received);
        if (message.substr(0, 5) == "/name") {
            name = message.substr(6);
            cout << "Client connected: " << name << endl;
            broadcast(name + " has joined the chat.", client_socket);
            Client new_client = { client_socket, name };
            mtx.lock();
            clients.push_back(new_client);
            mtx.unlock();
        }
        else if (message.substr(0, 6) == "/whisp") {
            size_t pos = message.find(' ');
            if (pos == string::npos) {
                continue;
            }
            string receiver_name = message.substr(7, pos - 7);
            string private_message = message.substr(pos + 1);
            for (auto& client : clients) {
                if (client.name == receiver_name) {
                    send(client.socket, private_message.c_str(), private_message.size() + 1, 0);
                    break;
                }
            }
        }
        else if (message.substr(0, 6) == "/file ") {
            size_t pos = message.find(' ');
            if (pos == string::npos) {
                continue;
            }
            string receiver_name = message.substr(7, pos - 7);
            string file_path = message.substr(pos + 1);
            for (auto& client : clients) {
                if (client.name == receiver_name) {
                    send_file(client.socket, file_path);
                    break;
                }
            }
        }
        else {
            cout << name << ": " << message << endl;
            broadcast(name + ": " + message, client_socket);
        }
    }
    mtx.lock();
    for (auto it = clients.begin(); it != clients.end(); ++it) {
        if (it->socket == client_socket) {
            cout << "Client disconnected: " << it->name << endl;
            broadcast(it->name + " has left the chat.", client_socket);
            clients.erase(it);
            break;
        }
    }
    mtx.unlock();
    closesocket(client_socket);
}

int main() {
    WSADATA wsa_data;
    int result = WSAStartup(MAKEWORD(2, 2), &wsa_data);
    if (result != 0) {
        cerr << "WSAStartup failed with error: " << result << endl;
        return -1;
    }
    SOCKET server_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (server_socket == INVALID_SOCKET) {
        cerr << "socket failed with error: " << WSAGetLastError() << endl;
        WSACleanup();
        return -1;
    }
    sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(12345);
    server_addr.sin_addr.s_addr = INADDR_ANY;
    result = bind(server_socket, (sockaddr*)&server_addr, sizeof(server_addr));
    if (result == SOCKET_ERROR) {
        cerr << "bind failed with error: " << WSAGetLastError() << endl;
        closesocket(server_socket);
        WSACleanup();
        return -1;
    }
    result = listen(server_socket, SOMAXCONN);
    if (result == SOCKET_ERROR) {
        cerr << "listen failed with error: " << WSAGetLastError() << endl;
        closesocket(server_socket);
        WSACleanup();
        return -1;
    }
    cout << "Waiting for clients to connect..." << endl;
    while (true) {
        SOCKET client_socket = accept(server_socket, NULL, NULL);
        if (client_socket == INVALID_SOCKET) {
            cerr << "accept failed with error: " << WSAGetLastError() << endl;
            closesocket(server_socket);
            WSACleanup();
            return -1;
        }
        thread t(handle_client, client_socket);
        t.detach();
    }
    closesocket(server_socket);
    WSACleanup();
    return 0;
}

在此程序中，我们使用了一个结构体 `Client` 来保存每个客户端的信息，包括套接字和名称。使用 `vector<Client>` 来保存所有连接的客户端。使用 `mutex` 来保证多线程安全。

`broadcast` 函数用于向除了发送者之外的所有客户端广播消息，可以选择不指定发送者。`send_file` 函数用于将文件发送给指定客户端。

在 `handle_client` 函数中，首先接收客户端发送的消息，如果消息是以 `/name` 开头，则表示客户端发送了自己的名称，将其保存到 `Client` 结构体中，并向所有客户端广播其加入聊天室的消息。如果消息是以 `/whisp` 开头，则表示客户端想私聊某个用户，将消息发送给指定用户。如果消息是以 `/file` 开头，则表示客户端想发送文件给某个用户，将文件发送给指定用户。其他情况则表示客户端发送了群聊消息，将其向所有客户端广播。

在主函数中，创建服务器套接字并绑定端口号，然后等待客户端连接。每当有客户端连接时，就创建一个新的线程来处理客户端。