完整的例子哈希字符串作为另一个字符串。

public static String sha256(final String base) {
    try{
        final MessageDigest digest = MessageDigest.getInstance("SHA-256");
        final byte[] hash = digest.digest(base.getBytes("UTF-8"));
        final StringBuilder hexString = new StringBuilder();
        for (int i = 0; i < hash.length; i++) {
            final String hex = Integer.toHexString(0xff & hash[i]);
            if(hex.length() == 1) 
              hexString.append('0');
            hexString.append(hex);
        }
        return hexString.toString();
    } catch(Exception ex){
       throw new RuntimeException(ex);
    }
}

这个方法返回一个带零的左填充String:

Java 10及以上版本:

public static String sha256(String text) {
    try {
        var messageDigest = MessageDigest.getInstance("SHA-256");
        var hash = messageDigest.digest(text.getBytes(StandardCharsets.UTF_8));
        
        return String.format("%064x", new BigInteger(1, hash));
    }
    catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
        return null;
    }
}

Java 8:

public static String sha256(String text) {
    try {
        MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
        byte[] hash = messageDigest.digest(text.getBytes(StandardCharsets.UTF_8));
        
        return String.format("%064x", new BigInteger(1, hash));
    }
    catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
        return null;
    }
}

顺便说一下，您可以使用“%064X”表示大写结果。

例子:

System.out.println(sha256("hello world 1"));

063dbf1d36387944a5f0ace625b4d3ee36b2daefd8bdaee5ede723637efb1cf4

与Linux cmd的比较:

$ echo -n 'hello world 1' | sha256sum 063 dbf1d36387944a5f0ace625b4d3ee36b2daefd8bdaee5ede723637efb1cf4 -

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;
}

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);

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();

下面是一个展示如何使用sha-256散列字符串的方法 算法和编码十六进制格式的结果。这是一种常用的散列格式，并将密码存储在数据库中:

public static String sha256(final String data) {
    try {
        final byte[] hash = MessageDigest.getInstance("SHA-256").digest(data.getBytes(StandardCharsets.UTF_8));
        final StringBuilder hashStr = new StringBuilder(hash.length);

        for (byte hashByte : hash)
            hashStr.append(Integer.toHexString(255 & hashByte));

        return hashStr.toString();
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
        return null;
    }
}