SHA-256
SHA-256（Secure Hash Algorithm 256-bit）是一种密码学安全哈希算法，用于将任意长度的数据转换为固定长度的哈希值，通常为256位（32字节）。SHA-256是SHA-2（Secure Hash Algorithm 2）系列算法的一部分，被广泛应用于密码学和数据完整性验证等领域。
我们可以使用SHA-256验证文件的完整性
Java实现方式
public class DigestUtils {public static String calculateSHA256(String filePath) throws IOException, NoSuchAlgorithmException {MessageDigest md = MessageDigest.getInstance("SHA-256");try (FileInputStream fis = new FileInputStream(filePath)) {byte[] buffer = new byte[8192];int bytesRead;while ((bytesRead = fis.read(buffer)) != -1) {md.update(buffer, 0, bytesRead);}}byte[] bytes = md.digest();StringBuilder sb = new StringBuilder();for (byte b : bytes) {sb.append(String.format("%02x", b));}return sb.toString();}
}Kotlin实现
object DigestUtils {@Throws(IOException::class, NoSuchAlgorithmException::class)fun calculateSHA256(filePath: String): String {val md = MessageDigest.getInstance("SHA-256")FileInputStream(filePath).use { fis ->val buffer = ByteArray(8192)var bytesRead: Intwhile (fis.read(buffer).also { bytesRead = it } != -1) {md.update(buffer, 0, bytesRead)}}val bytes = md.digest()val sb = StringBuilder()for (b in bytes) {sb.append(String.format("%02x", b))}return sb.toString()}
}MD5
MD5（Message Digest Algorithm 5）是一种广泛使用的哈希函数，用于将任意长度的数据转换为固定长度的哈希值，通常为128位（16字节）。MD5 的主要特点是产生的哈希值具有较高的唯一性和不可逆性，通常用于验证数据的完整性、密码存储、数字签名等领域。
Java
public class MD5Utils {public static String calculateMD5(String input) {try {MessageDigest md = MessageDigest.getInstance("MD5");byte[] hashBytes = md.digest(input.getBytes(StandardCharsets.UTF_8));// Convert the byte array to a hexadecimal string representationBigInteger number = new BigInteger(1, hashBytes);StringBuilder hexString = new StringBuilder(number.toString(16));while (hexString.length() < 32) {hexString.insert(0, "0");}return hexString.toString();} catch (NoSuchAlgorithmException e) {e.printStackTrace();}return null;}
}Kotlin实现
object MD5Utils {fun calculateMD5(input: String): String {try {val md = MessageDigest.getInstance("MD5")val hashBytes = md.digest(input.toByteArray(StandardCharsets.UTF_8))val number = BigInteger(1, hashBytes)val hexString = StringBuilder(number.toString(16))while (hexString.length < 32) {hexString.insert(0, "0")}return hexString.toString()} catch (e: NoSuchAlgorithmException) {e.printStackTrace()} return ""}
}
)
