1.web服务器中收发REST接口

1.C语言在linux中创建web服务器收发消息

  1. server.c

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    #include <stdio.h>
    #include <string.h>
    #include <unistd.h>
    #include <arpa/inet.h>

    void send_cors_headers(int client) {
        dprintf(client,
            "Access-Control-Allow-Origin: *\r\n"
            "Access-Control-Allow-Methods: GET, POST, OPTIONS\r\n"
            "Access-Control-Allow-Headers: Content-Type\r\n"
        );
    }

    int main() {
        int server_fd = socket(AF_INET, SOCK_STREAM, 0);
        int opt = 1;
        setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

        struct sockaddr_in addr = {
            .sin_family = AF_INET,
            .sin_port = htons(3000),
            .sin_addr.s_addr = INADDR_ANY
        };

        if (bind(server_fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
            perror("bind");
            return 1;
        }

        if (listen(server_fd, 10) < 0) {
            perror("listen");
            return 1;
        }

        printf("REST server running at http://localhost:3000\n");

        while (1) {
            int client = accept(server_fd, NULL, NULL);

            char buf[4096] = {0};
            read(client, buf, sizeof(buf) - 1);

            char method[8], path[128];
            sscanf(buf, "%s %s", method, path);

            // OPTIONS
            if (strcmp(method, "OPTIONS") == 0) {
                dprintf(client,
                    "HTTP/1.1 204 No Content\r\n"
                );
                send_cors_headers(client);
                dprintf(client, "\r\n");
                close(client);
                continue;
            }

            // GET /hello
            if (strcmp(method, "GET") == 0 && strcmp(path, "/hello") == 0) {
                const char *body = "{\"message\":\"Hello REST\"}";
                dprintf(client,
                    "HTTP/1.1 200 OK\r\n"
                );
                send_cors_headers(client);
                dprintf(client,
                    "Content-Type: application/json\r\n"
                    "Content-Length: %zu\r\n"
                    "\r\n"
                    "%s",
                    strlen(body), body
                );
                close(client);
                continue;
            }

            // POST /echo
            if (strcmp(method, "POST") == 0 && strcmp(path, "/echo") == 0) {
                char *body = strstr(buf, "\r\n\r\n");
                body = body ? body + 4 : "";

                char response[4096];
                snprintf(response, sizeof(response),
                    "{\"you_sent\":\"%s\"}", body);

                dprintf(client,
                    "HTTP/1.1 200 OK\r\n"
                );
                send_cors_headers(client);
                dprintf(client,
                    "Content-Type: application/json\r\n"
                    "Content-Length: %zu\r\n"
                    "\r\n"
                    "%s",
                    strlen(response), response
                );
                close(client);
                continue;
            }

            // 404
            const char *body = "{\"error\":\"Not Found\"}";
            dprintf(client,
                "HTTP/1.1 404 Not Found\r\n"
            );
            send_cors_headers(client);
            dprintf(client,
                "Content-Type: application/json\r\n"
                "Content-Length: %zu\r\n"
                "\r\n"
                "%s",
                strlen(body), body
            );

            close(client);
        }

        close(server_fd);
        return 0;
    }

  2. 编译运行

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    gcc -o server -s server.c
    ./server

  3. curl命令发送pos请求调用接口

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    curl -X POST http://localhost:3000/echo -d "qi is testing"

2.创建post.html发送post请求调用REST API

  1. post.html

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    <!DOCTYPE html>
    <html>
    <head>
      <meta charset="UTF-8">
      <title>REST API Test</title>
    </head>
    <body>
      <h1>调用 C 语言 REST 服务</h1>

      <button id="btnHello">GET /hello</button>
      <pre id="helloResult"></pre>

      <hr>

      <input id="echoInput" placeholder="输入要发送的内容">
      <button id="btnEcho">POST /echo</button>
      <pre id="echoResult"></pre>

      <script>
        // 调用 GET /hello
        document.getElementById('btnHello').onclick = async () => {
          const res = await fetch('http://192.168.1.20:3000/hello');
          const data = await res.json();
          document.getElementById('helloResult').textContent =
            JSON.stringify(data, null, 2);
        };

        // 调用 POST /echo
        document.getElementById('btnEcho').onclick = async () => {
          const text = document.getElementById('echoInput').value;

          const res = await fetch('http://192.168.1.20:3000/echo', {
            method: 'POST',
            headers: { 'Content-Type': 'text/plain' },
            body: text
          });

          const data = await res.json();
          document.getElementById('echoResult').textContent =
            JSON.stringify(data, null, 2);
        };
      </script>
    </body>
    </html>

  2. 浏览器打开post.html

  3. 点击网页表单，在浏览器中查看结果