另一个替代方案是Guava，它有一套易于使用的哈希实用程序。例如，使用SHA256作为十六进制字符串来哈希字符串，你可以简单地这样做:

final String hashed = Hashing.sha256()
        .hashString("your input", StandardCharsets.UTF_8)
        .toString();

下面是一种将摘要转换为十六进制字符串的更有效的方法:

private static final char[] hexArray = "0123456789abcdef".toCharArray();

public static String getSHA256(String data) {
    StringBuilder sb = new StringBuilder();
    try {
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(data.getBytes());
        byte[] byteData = md.digest();
        sb.append(bytesToHex(byteData);
    } catch(Exception e) {
        e.printStackTrace();
    }
    return sb.toString();
}

private static String bytesToHex(byte[] bytes) {
    char[] hexChars = new char[bytes.length * 2];
    for ( int j = 0; j < bytes.length; j++ ) {
        int v = bytes[j] & 0xFF;
        hexChars[j * 2] = hexArray[v >>> 4];
        hexChars[j * 2 + 1] = hexArray[v & 0x0F];
    }
    return String.valueOf(hexChars);
}

有人知道Java中更快的方法吗?

这是我用于哈希的:

String pass = "password";

MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
byte hashBytes[] = messageDigest.digest(pass.getBytes(StandardCharsets.UTF_8));
BigInteger noHash = new BigInteger(1, hashBytes);
String hashStr = noHash.toString(16);

输出:5e884898da28047151d0e56f8dc6292773603d0d6aabbdd62a11ef721d1542d8

String hashWith256(String textToHash) {
    MessageDigest digest = MessageDigest.getInstance("SHA-256");
    byte[] byteOfTextToHash = textToHash.getBytes(StandardCharsets.UTF_8);
    byte[] hashedByetArray = digest.digest(byteOfTextToHash);
    String encoded = Base64.getEncoder().encodeToString(hashedByetArray);
    return encoded;
}

这是我使用Kotlin的方法:

private fun getHashFromEmailString(email : String) : String{
    val charset = Charsets.UTF_8
    val byteArray = email.toByteArray(charset)
    val digest = MessageDigest.getInstance("SHA-256")
    val hash = digest.digest(byteArray)

    return hash.fold("", { str, it -> str + "%02x".format(it)})
}

如果你使用的是Java 8，你可以这样编码字节[]

MessageDigest digest = MessageDigest.getInstance("SHA-256");
byte[] hash = digest.digest(text.getBytes(StandardCharsets.UTF_8));
String encoded = Base64.getEncoder().encodeToString(hash);