如何使用EtherCard库和Arduino Uno通过POST将此JSon发送到服务器？

#include <EtherCard.h>

// 定义服务器的IP地址和端口号
static byte myip[] = {192, 168, 0, 100};
static byte gwip[] = {192, 168, 0, 1};
static byte dnsip[] = {192, 168, 0, 1};
static byte hisip[] = {192, 168, 0, 101};
static word myport = 8888;

// 定义MAC地址
static byte mymac[] = {0x74,0x69,0x69,0x2D,0x30,0x31};

// 定义发送的JSON数据
static char json[] = "{\"key\":\"value\"}";

// 定义发送缓冲区
static byte Ethernet::buffer[700];

void setup() {
  // 初始化以太网连接
  if (ether.begin(sizeof Ethernet::buffer, mymac) == 0) {
    Serial.println(F("Failed to access Ethernet controller"));
    while (1);
  }
  ether.staticSetup(myip, gwip, dnsip);
  ether.printIp("My IP: ", ether.myip);
}

void loop() {
  // 发送POST请求
  if (ether.packetLoop(ether.packetReceive())) {
    // 构建HTTP请求头
    char httpHeader[] = "POST /path/to/endpoint HTTP/1.1\r\n"
                        "Host: example.com\r\n"
                        "Content-Type: application/json\r\n"
                        "Content-Length: %d\r\n"
                        "\r\n";

    // 计算JSON数据的长度
    int jsonLength = strlen(json);

    // 计算HTTP请求头的长度
    int headerLength = sizeof(httpHeader) - 2 + 3; // 2个占位符 %d，3个数字

    // 构建完整的HTTP请求
    char httpRequest[headerLength + jsonLength];
    sprintf(httpRequest, httpHeader, jsonLength);
    strcat(httpRequest, json);

    // 发送HTTP请求
    ether.browseUrl(PSTR("example.com"), myport, httpRequest, NULL);
  }
}