Método DigestInputStream.setMessageDigest() en Java con ejemplos

El método setMessageDigest() de la clase java.security.DigestInputStream utilizado para asignar el MessageDigest especificado al objeto DigestInputStream.

Sintaxis: 

public void setMessageDigest(MessageDigest digest)

Valor devuelto: este método no tiene nada que devolver.

Nota: Todos los programas de este artículo no se ejecutarán en IDE en línea ya que no existe un archivo de ‘nombre’. Puede verificar este código en el compilador de Java en su sistema. Para verificar este código, cree un archivo ‘nombre’ en su sistema.

A continuación se muestran los ejemplos para ilustrar el método setMessageDigest() :

Ejemplo 1:  

// Java program to demonstrate
// setMessageDigest() method
 
import java.security.*;
import java.util.*;
import java.io.*;
 
public class GFG {
    public static void main(String[] argv)
    {
        try {
 
            // creating the object of MessageDigest
            // and getting instance
            // By using getInstance() method
            MessageDigest sr
                = MessageDigest.getInstance("MD5");
 
            // creating and initializing
            // object of InputStream
            InputStream is
                = new FileInputStream(
                    "f:/java/name.txt");
 
            // creating and initializing
            // object of DigestInputStream
            DigestInputStream di
                = new DigestInputStream(is, sr);
 
            // display the result
            System.out.println(
                "MessageDigest before assigning : "
                + di.getMessageDigest());
 
            // assigning the MessageDigest to this stream
            // using setMessageDigest() method
            di.setMessageDigest(
                MessageDigest
                    .getInstance("SHA-1"));
 
            // display the result
            System.out.println(
                "MessageDigest after assigning : "
                + di.getMessageDigest());
        }
 
        catch (NoSuchAlgorithmException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

MessageDigest before assigning : MD5 Message Digest from SUN, 

MessageDigest after assigning : SHA-1 Message Digest from SUN, 

Ejemplo 2: 

// Java program to demonstrate
// setMessageDigest() method
 
import java.security.*;
import java.util.*;
import java.io.*;
 
public class GFG {
    public static void main(String[] argv)
    {
        try {
            // creating the object of MessageDigest
            // and getting instance
            // By using getInstance() method
            MessageDigest sr
                = MessageDigest.getInstance("SHA-1");
 
            // creating and initializing
            // object of InputStream
            InputStream is
                = new FileInputStream(
                    "f:/java/name.txt");
 
            // creating and initializing
            // object of DigestInputStream
            DigestInputStream di
                = new DigestInputStream(is, sr);
 
            // display the result
            System.out.println(
                "MessageDigest before assigning : "
                + di.getMessageDigest());
 
            // assigning the MessageDigest to this stream
            // using setMessageDigest() method
            di.setMessageDigest(
                MessageDigest.getInstance("MD5"));
 
            // display the result
            System.out.println(
                "MessageDigest after assigning : "
                + di.getMessageDigest());
        }
 
        catch (NoSuchAlgorithmException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

MessageDigest before assigning : SHA-1 Message Digest from SUN, 

MessageDigest after assigning : MD5 Message Digest from SUN,  

Referencia: https://docs.oracle.com/javase/9/docs/api/java/security/DigestInputStream.html#setMessageDigest-java.security.MessageDigest-