Java SHA-256 Hash用法及代碼示例

import java.math.BigInteger;  
import java.nio.charset.StandardCharsets; 
import java.security.MessageDigest;  
import java.security.NoSuchAlgorithmException;  
  
// Java program to calculate SHA hash value  
  
class GFG {  
    public static byte[] getSHA(String input) throws NoSuchAlgorithmException 
    {  
        // Static getInstance method is called with hashing SHA  
        MessageDigest md = MessageDigest.getInstance("SHA-256");  
  
        // digest() method called  
        // to calculate message digest of an input  
        // and return array of byte 
        return md.digest(input.getBytes(StandardCharsets.UTF_8));  
    } 
    
    public static String toHexString(byte[] hash) 
    { 
        // Convert byte array into signum representation  
        BigInteger number = new BigInteger(1, hash);  
  
        // Convert message digest into hex value  
        StringBuilder hexString = new StringBuilder(number.toString(16));  
  
        // Pad with leading zeros 
        while (hexString.length() < 32)  
        {  
            hexString.insert(0, '0');  
        }  
  
        return hexString.toString();  
    } 
  
    // Driver code  
    public static void main(String args[]) 
    {  
        try 
        { 
            System.out.println("HashCode Generated by SHA-256 for:");  
  
            String s1 = "GeeksForGeeks";  
            System.out.println("\n" + s1 + ":" + toHexString(getSHA(s1)));  
  
            String s2 = "hello world";  
            System.out.println("\n" + s2 + ":" + toHexString(getSHA(s2)));  
        } 
        // For specifying wrong message digest algorithms  
        catch (NoSuchAlgorithmException e) {  
            System.out.println("Exception thrown for incorrect algorithm:" + e);  
        }  
    }  
}