ESP32-CAM 上传图片到服务器：使用 multipart/form-data POST 请求

您可以使用以下代码将图像作为'multipart/form-data' POST请求上传到服务器：

#include <WiFi.h>
#include <WiFiClient.h>
#include <WiFiClientSecure.h>
#include <HTTPClient.h>
#include <esp_camera.h>
#include "esp_http_client.h"

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* serverUrl = "http://your_server_url/upload.php";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");

  camera_config_t config;
  config.ledc_channel = LEDC_CHANNEL_0;
  config.ledc_timer = LEDC_TIMER_0;
  config.pin_d0 = 5;
  config.pin_d1 = 18;
  config.pin_d2 = 19;
  config.pin_d3 = 21;
  config.pin_d4 = 36;
  config.pin_d5 = 39;
  config.pin_d6 = 34;
  config.pin_d7 = 35;
  config.pin_xclk = 0;
  config.pin_pclk = 22;
  config.pin_vsync = 25;
  config.pin_href = 23;
  config.pin_sscb_sda = 26;
  config.pin_sscb_scl = 27;
  config.pin_pwdn = 32;
  config.pin_reset = -1;
  config.xclk_freq_hz = 20000000;
  config.pixel_format = PIXFORMAT_JPEG;
  config.frame_size = FRAMESIZE_SXGA;
  config.jpeg_quality = 10;
  config.fb_count = 2;

  esp_err_t err = esp_camera_init(&config);
  if (err != ESP_OK) {
    Serial.printf("Camera init failed with error 0x%x", err);
    return;
  }
}

void loop() {
  // Take a photo
  camera_fb_t* fb = esp_camera_fb_get();
  if (!fb) {
    Serial.println("Camera capture failed");
    return;
  }

  // Prepare the HTTP request
  WiFiClient client;
  HTTPClient http;
  http.begin(client, serverUrl);
  http.addHeader("Content-Type", "multipart/form-data");

  // Prepare the image data as a multipart form data
  esp_http_client_config_t config = {
    .url = serverUrl,
    .method = HTTP_METHOD_POST,
    .event_handler = NULL,
  };
  esp_http_client_handle_t client2 = esp_http_client_init(&config);
  esp_http_client_set_header(client2, "Content-Type", "multipart/form-data");
  esp_http_client_set_post_field(client2, (const char*)fb->buf, fb->len);
  esp_http_client_set_header(client2, "Content-Disposition", "form-data; name=\"image\"; filename=\"image.jpg\"");
  esp_err_t err2 = esp_http_client_perform(client2);
  if (err2 != ESP_OK) {
    Serial.printf("HTTP POST request failed with error %d", err2);
  }

  // Release the image buffer
  esp_camera_fb_return(fb);

  // Wait for a while before taking another photo
  delay(5000);
}

在此示例中，我们使用 esp_camera 库从 ESP32-CAM 拍摄照片，然后使用 HTTPClient 库将图像作为'multipart/form-data' POST 请求上传到服务器。在上传之前，我们将'Content-Type' 标头设置为'multipart/form-data'，并将图像数据设置为 POST 字段。然后，我们将'Content-Disposition' 标头设置为'form-data; name="image"; filename="image.jpg"'，以指定表单数据的名称和文件名。最后，我们使用 esp_http_client 库执行 HTTP POST 请求，并检查错误代码以确保请求成功。