在C語言中，我們經常會需要攔截HTTP請求并返回JSON數據。這可以通過基于Socket的HTTP服務器來實現。下面是一個簡單的例子：

#include#include#include#include#include#include#define MAX_BUFFER_SIZE 1024
int main() {
// 創建套接字
int server_socket = socket(AF_INET, SOCK_STREAM, 0);
if (server_socket == -1) {
perror("Failed to create socket");
return 1;
}
// 綁定端口
struct sockaddr_in server_address;
server_address.sin_family = AF_INET;
server_address.sin_port = htons(8080);
server_address.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(server_socket, (struct sockaddr *)&server_address, sizeof(server_address)) == -1) {
perror("Failed to bind port 8080");
return 1;
}
// 監聽
if (listen(server_socket, 5) == -1) {
perror("Failed to listen");
return 1;
}
// 處理HTTP請求
while (1) {
int client_socket = accept(server_socket, NULL, NULL);
if (client_socket< 0) {
perror("Failed to accept");
return 1;
}
// 讀取請求
char buffer[MAX_BUFFER_SIZE];
int size = read(client_socket, buffer, MAX_BUFFER_SIZE);
if (size == -1) {
perror("Failed to read request");
return 1;
}
// 響應JSON數據
const char* response = "{ \"message\": \"Hello, World!\" }";
char header[MAX_BUFFER_SIZE];
snprintf(header, MAX_BUFFER_SIZE, "HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: application/json\r\n\r\n", strlen(response));
if (write(client_socket, header, strlen(header)) == -1) {
perror("Failed to write response header");
return 1;
}
if (write(client_socket, response, strlen(response)) == -1) {
perror("Failed to write response body");
return 1;
}
// 關閉客戶端套接字
close(client_socket);
}
// 關閉服務器套接字
close(server_socket);
return 0;
}

上述代碼創建了一個基于Socket的HTTP服務器，并通過讀取HTTP請求并返回JSON數據來響應客戶端請求。我們可以使用curl來測試該服務器：

$ curl http://localhost:8080
{ "message": "Hello, World!" }

該服務器返回了一個JSON對象，其中包含了一條消息："Hello, World!"。這個例子可以作為一個基礎模板，用于構建更復雜的HTTP服務器。