Linux下C++使用多线程技术实现多客户端并发访问指定服务器 客户端和服务端代码

以下是一个简单的多线程 C++ 客户端和服务端代码，可以实现多客户端并发访问指定服务器：

### 服务端代码

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>

using namespace std;

#define PORT 8888
#define MAX_CLIENTS 10
#define BUFFER_SIZE 1024

void* handle_client(void* client_socket_void_ptr) {
    int client_socket = *(int*)client_socket_void_ptr;
    char buffer[BUFFER_SIZE];
    while (true) {
        memset(buffer, 0, sizeof(buffer));
        int bytes_received = recv(client_socket, buffer, sizeof(buffer), 0);
        if (bytes_received == -1) {
            cerr << "Error in recv." << endl;
            close(client_socket);
            return NULL;
        } else if (bytes_received == 0) {
            cout << "Client disconnected." << endl;
            close(client_socket);
            return NULL;
        }
        cout << "Received: " << buffer << endl;
        string response = "Server received: ";
        response += buffer;
        int bytes_sent = send(client_socket, response.c_str(), response.length(), 0);
        if (bytes_sent == -1) {
            cerr << "Error in send." << endl;
            close(client_socket);
            return NULL;
        }
    }
}

int main() {
    int server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket == -1) {
        cerr << "Error creating server socket." << endl;
        return 1;
    }
    sockaddr_in server_address;
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(PORT);
    server_address.sin_addr.s_addr = INADDR_ANY;
    if (bind(server_socket, (sockaddr*)&server_address, sizeof(server_address)) == -1) {
        cerr << "Error binding server socket." << endl;
        return 1;
    }
    if (listen(server_socket, MAX_CLIENTS) == -1) {
        cerr << "Error listening on server socket." << endl;
        return 1;
    }
    cout << "Server started. Listening on port " << PORT << "." << endl;
    while (true) {
        sockaddr_in client_address;
        socklen_t client_address_size = sizeof(client_address);
        int client_socket = accept(server_socket, (sockaddr*)&client_address, &client_address_size);
        if (client_socket == -1) {
            cerr << "Error accepting client socket." << endl;
            continue;
        }
        cout << "Client connected from " << inet_ntoa(client_address.sin_addr) << ":" << ntohs(client_address.sin_port) << "." << endl;
        pthread_t thread;
        if (pthread_create(&thread, NULL, handle_client, &client_socket) != 0) {
            cerr << "Error creating thread." << endl;
            close(client_socket);
            continue;
        }
        pthread_detach(thread);
    }
    close(server_socket);
    return 0;
}

### 客户端代码

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>

using namespace std;

#define PORT 8888
#define BUFFER_SIZE 1024

void* receive_messages(void* socket_void_ptr) {
    int socket = *(int*)socket_void_ptr;
    char buffer[BUFFER_SIZE];
    while (true) {
        memset(buffer, 0, sizeof(buffer));
        int bytes_received = recv(socket, buffer, sizeof(buffer), 0);
        if (bytes_received == -1) {
            cerr << "Error in recv." << endl;
            close(socket);
            exit(1);
        } else if (bytes_received == 0) {
            cout << "Server disconnected." << endl;
            close(socket);
            exit(0);
        }
        cout << "Received: " << buffer << endl;
    }
}

int main(int argc, char** argv) {
    if (argc != 2) {
        cerr << "Usage: " << argv[0] << " <server_ip_address>" << endl;
        return 1;
    }
    int client_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (client_socket == -1) {
        cerr << "Error creating client socket." << endl;
        return 1;
    }
    sockaddr_in server_address;
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(PORT);
    if (inet_pton(AF_INET, argv[1], &server_address.sin_addr) == -1) {
        cerr << "Error converting server IP address." << endl;
        return 1;
    }
    if (connect(client_socket, (sockaddr*)&server_address, sizeof(server_address)) == -1) {
        cerr << "Error connecting to server." << endl;
        return 1;
    }
    cout << "Connected to server " << argv[1] << ":" << PORT << "." << endl;
    pthread_t thread;
    if (pthread_create(&thread, NULL, receive_messages, &client_socket) != 0) {
        cerr << "Error creating thread." << endl;
        close(client_socket);
        return 1;
    }
    string message;
    while (true) {
        getline(cin, message);
        if (message.length() == 0) {
            continue;
        }
        int bytes_sent = send(client_socket, message.c_str(), message.length(), 0);
        if (bytes_sent == -1) {
            cerr << "Error in send." << endl;
            close(client_socket);
            return 1;
        }
    }
    close(client_socket);
    return 0;
}

在 Linux 系统中编译这些代码可以使用以下命令：

g++ -pthread server.cpp -o server
g++ -pthread client.cpp -o client

然后分别运行 `server` 和 `client` 可执行文件即可。