使用javascript计算大文件的MD5散列

function calculateMD5(file) {
  return new Promise((resolve, reject) => {
    const chunkSize = 2 * 1024 * 1024; // 每个文件块的大小，这里设置为2MB
    const chunks = Math.ceil(file.size / chunkSize);
    const fileReader = new FileReader();
    const cryptoSubtle = window.crypto.subtle;

    const hashBuffer = new ArrayBuffer(chunks * 16); // 存储所有文件块的散列值

    let currentChunk = 0;

    fileReader.onload = function (e) {
      const chunkBuffer = e.target.result;

      cryptoSubtle.digest("MD5", chunkBuffer)
        .then((hashValue) => {
          const hashArray = Array.from(new Uint8Array(hashValue));
          const hashView = new DataView(hashBuffer);

          for (let i = 0; i < hashArray.length; i++) {
            hashView.setUint8(currentChunk * 16 + i, hashArray[i]);
          }

          currentChunk++;

          if (currentChunk < chunks) {
            processNextChunk();
          } else {
            const finalHash = calculateFinalHash(hashBuffer);
            resolve(finalHash);
          }
        })
        .catch((error) => {
          reject(error);
        });
    };

    function processNextChunk() {
      const start = currentChunk * chunkSize;
      const end = Math.min(start + chunkSize, file.size);
      const chunk = file.slice(start, end);
      fileReader.readAsArrayBuffer(chunk);
    }

    function calculateFinalHash(hashBuffer) {
      return cryptoSubtle.digest("MD5", hashBuffer)
        .then((finalHashValue) => {
          const finalHashArray = Array.from(new Uint8Array(finalHashValue));
          const finalHash = finalHashArray.map((byte) => byte.toString(16).padStart(2, "0")).join("");
          return finalHash;
        });
    }

    processNextChunk();
  });
}

// 使用示例
const fileInput = document.getElementById("file-input");

fileInput.addEventListener("change", (event) => {
  const file = event.target.files[0];

  calculateMD5(file)
    .then((md5Hash) => {
      console.log("MD5 Hash:", md5Hash);
    })
    .catch((error) => {
      console.error("Error:", error);
    });
});