以十六进制发送Javascript POST XMLHttpRequest文件内容

// 获取文件内容
var fileInput = document.getElementById('fileInput');
var file = fileInput.files[0];

// 将文件内容转换为十六进制
var reader = new FileReader();
reader.onload = function(e) {
  var arrayBuffer = e.target.result;
  var hexString = arrayBufferToHexString(arrayBuffer);

  // 构建XMLHttpRequest对象
  var xhr = new XMLHttpRequest();

  // 设置请求参数
  xhr.open('POST', 'http://example.com/upload', true);
  xhr.setRequestHeader('Content-Type', 'multipart/form-data');
  xhr.send(hexString);
};

reader.readAsArrayBuffer(file);

// 将ArrayBuffer转换为十六进制字符串
function arrayBufferToHexString(arrayBuffer) {
  var byteArray = new Uint8Array(arrayBuffer);
  var hexString = '';
  for (var i = 0; i < byteArray.length; i++) {
    var hex = byteArray[i].toString(16);
    hex = (hex.length === 1) ? '0' + hex : hex;
    hexString += hex;
  }
  return hexString;
}