Added example to hash the image file.

YogenRaii · YogenRaii · commit 34ffa267efe3 · 2017-11-16T16:12:40.000-08:00
diff --git a/pom.xml b/pom.xml
@@ -106,6 +106,13 @@
 			<version>3.0</version>
 		</dependency>
 
+		<!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
+		<dependency>
+			<groupId>com.google.guava</groupId>
+			<artifactId>guava</artifactId>
+			<version>19.0</version>
+		</dependency>
+
 		<dependency>
 			<groupId>joda-time</groupId>
 			<artifactId>joda-time</artifactId>
diff --git a/src/main/java/com/eprogrammerz/examples/general/hashGenerator/HashGenerator.java b/src/main/java/com/eprogrammerz/examples/general/hashGenerator/HashGenerator.java
@@ -0,0 +1,114 @@
+package com.eprogrammerz.examples.general.hashGenerator;
+
+import com.google.common.io.ByteStreams;
+import lombok.extern.slf4j.Slf4j;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.*;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+import java.util.Formatter;
+
+import static org.junit.Assert.assertEquals;
+
+@Slf4j
+@RunWith(JUnit4.class)
+public class HashGenerator {
+    public static final String HASH_ALGORITHM = "MD5";
+
+    @Test
+    public void testHashGenerators() throws IOException, NoSuchAlgorithmException {
+        File input = new File("/Users/yrai/Downloads/E.tif");
+
+//        String defHashValue = getHashWithByteBuffer(input);
+
+        long startTime = System.currentTimeMillis();
+        String handBufHashValue = getImageHashValue(input);
+        long completeTime = System.currentTimeMillis();
+        System.out.println(completeTime - startTime);
+
+        startTime = System.currentTimeMillis();
+        String hashValueWithCopy = getImageHashValueWithCopy(input);
+        completeTime = System.currentTimeMillis();
+        System.out.println(completeTime - startTime);
+
+        assertEquals(handBufHashValue, hashValueWithCopy);
+
+        getHashWithByteBuffer(input);
+    }
+
+    public static String getImageHashValue(File input) throws IOException, NoSuchAlgorithmException {
+        InputStream is = new FileInputStream(input);
+
+        MessageDigest messageDigest = null;
+        try {
+            messageDigest = MessageDigest.getInstance(HASH_ALGORITHM);
+        } catch (NoSuchAlgorithmException e) {
+            log.error("Invalid hash algorithm: {}", HASH_ALGORITHM);
+        }
+
+        final byte[] buffer = new byte[1024];
+        for (int read = 0; (read = is.read(buffer)) != -1;) {
+            messageDigest.update(buffer, 0, read);
+        }
+        // Convert the byte to hex format
+        try (Formatter formatter = new Formatter()) {
+            for (final byte b : messageDigest.digest()) {
+                formatter.format("%02x", b);
+            }
+            return formatter.toString();
+        }
+    }
+
+    public static String getImageHashValueWithCopy(File input) throws IOException, NoSuchAlgorithmException {
+        InputStream is = new FileInputStream(input);
+
+        MessageDigest messageDigest = null;
+        try {
+            messageDigest = MessageDigest.getInstance(HASH_ALGORITHM);
+        } catch (NoSuchAlgorithmException e) {
+            log.error("Invalid hash algorithm: {}", HASH_ALGORITHM);
+        }
+
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        ByteStreams.copy(is, out);
+
+        byte[] data = out.toByteArray();
+
+        messageDigest.update(data);
+        // Convert the byte to hex format
+        try (Formatter formatter = new Formatter()) {
+            for (final byte b : messageDigest.digest()) {
+                formatter.format("%02x", b);
+            }
+            return formatter.toString();
+        }
+    }
+
+    public static String getHashWithByteBuffer(File input) throws IOException, NoSuchAlgorithmException {
+        BufferedImage buffImg = ImageIO.read(input);
+
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        ImageIO.write(buffImg, "tif", outputStream);
+        byte[] data = outputStream.toByteArray();
+
+        MessageDigest md = MessageDigest.getInstance(HASH_ALGORITHM);
+        md.update(data);
+        byte[] hash = md.digest();
+
+        String hashValue = null;
+
+        try (Formatter formatter = new Formatter()) {
+            for (final byte b : hash) {
+                formatter.format("%02x", b);
+            }
+            hashValue = formatter.toString();
+        }
+        return hashValue;
+    }
+}
