如何从esp8266向本地服务器发送有限的json数据(存储在SPIFF中)？

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <ArduinoJson.h>
#include <FS.h>

const char* ssid = "YourWiFiSSID";
const char* password = "YourWiFiPassword";
const char* serverIP = "YourServerIP";
const int serverPort = 80;

void setup() {
  Serial.begin(115200);

  // 连接到WiFi网络
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");

  // 挂载SPIFFS文件系统
  if (!SPIFFS.begin()) {
    Serial.println("Failed to mount file system");
    return;
  }

  // 创建JSON数据
  DynamicJsonDocument jsonDoc(1024);
  jsonDoc["sensor"] = "temperature";
  jsonDoc["value"] = 25.5;

  // 将JSON数据保存到SPIFFS中
  File jsonFile = SPIFFS.open("/data.json", "w");
  if (!jsonFile) {
    Serial.println("Failed to open file for writing");
    return;
  }
  serializeJson(jsonDoc, jsonFile);
  jsonFile.close();

  // 建立HTTP连接并发送JSON数据
  HTTPClient http;
  http.begin("http://" + String(serverIP) + ":" + String(serverPort) + "/endpoint");
  http.addHeader("Content-Type", "application/json");

  File file = SPIFFS.open("/data.json", "r");
  if (!file) {
    Serial.println("Failed to open file for reading");
    return;
  }

  int fileSize = file.size();
  std::unique_ptr<char[]> buf(new char[fileSize]);
  file.readBytes(buf.get(), fileSize);
  file.close();

  int httpResponseCode = http.POST(buf.get(), fileSize);
  if (httpResponseCode > 0) {
    String response = http.getString();
    Serial.println("Server response: " + response);
  } else {
    Serial.println("Error sending POST request");
  }

  http.end();
}

void loop() {
  // 主循环中的其他代码
}