Adding SHA-256 hashing impl and test classes

core-java/pom.xml

@@ -46,6 +46,11 @@
 			<version>3.3</version>
 		</dependency>
 
+		<dependency>
+			<groupId>org.bouncycastle</groupId>
+			<artifactId>bcprov-jdk15on</artifactId>
+			<version>1.55</version>
+		</dependency>
 		<!-- web -->
 
 		<!-- marshalling -->

core-java/src/main/java/com/baeldung/hashing/SHA256Hashing.java

@@ -0,0 +1,51 @@
+package com.baeldung.hashing;
+
+
+import com.google.common.hash.Hashing;
+import org.apache.commons.codec.digest.DigestUtils;
+import org.bouncycastle.util.encoders.Hex;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class SHA256Hashing {
+
+    public static String HashWithJavaMessageDigest(final String originalString)
+            throws NoSuchAlgorithmException {
+        final MessageDigest digest = MessageDigest.getInstance("SHA-256");
+        final byte[] encodedhash = digest.digest(
+                originalString.getBytes(StandardCharsets.UTF_8));
+        return bytesToHex(encodedhash);
+    }
+
+    public static String HashWithGuava(final String originalString) {
+        final String sha256hex = Hashing.sha256().hashString(
+                originalString, StandardCharsets.UTF_8).toString();
+        return sha256hex;
+    }
+
+    public static String HashWithApacheCommons(final String originalString) {
+        final String sha256hex = DigestUtils.sha256Hex(originalString);
+        return sha256hex;
+    }
+
+    public static String HashWithBouncyCastle(final String originalString)
+            throws NoSuchAlgorithmException {
+        final MessageDigest digest = MessageDigest.getInstance("SHA-256");
+        final byte[] hash = digest.digest(
+                originalString.getBytes(StandardCharsets.UTF_8));
+        final String sha256hex = new String(Hex.encode(hash));
+        return sha256hex;
+    }
+
+    private static String bytesToHex(byte[] hash) {
+        StringBuffer hexString = new StringBuffer();
+        for (int i = 0; i < hash.length; i++) {
+            String hex = Integer.toHexString(0xff & hash[i]);
+            if(hex.length() == 1) hexString.append('0');
+            hexString.append(hex);
+        }
+        return hexString.toString();
+    }
+}

core-java/src/test/java/com/baeldung/hashing/SHA256HashingTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.hashing;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+
+public class SHA256HashingTest {
+
+    private static String originalValue = "abc123";
+    private static String hashedValue =
+            "6ca13d52ca70c883e0f0bb101e425a89e8624de51db2d2392593af6a84118090";
+
+    @Test
+    public void testHashWithJavaMessageDigest() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithJavaMessageDigest(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+
+    @Test
+    public void testHashWithGuava() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithApacheCommons(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+
+    @Test
+    public void testHashWithApacheCommans() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithGuava(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+
+    @Test
+    public void testHashWithBouncyCastle() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithBouncyCastle(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+}