Cleanup Utils.md5 method by using DatatypeConverter and DigestInputStream classes

src/com/sheepit/client/Utils.java

@@ -21,11 +21,12 @@ package com.sheepit.client;
 
 import java.io.File;
 import java.io.FileInputStream;
-import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.math.BigInteger;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.security.DigestInputStream;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.Calendar;
@@ -36,6 +37,8 @@ import java.util.regex.Pattern;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipInputStream;
 
+import javax.xml.bind.DatatypeConverter;
+
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.NodeList;
@@ -102,55 +105,19 @@ public class Utils {
 	}
 	
 	public static String md5(String path_of_file_) {
-		MessageDigest digest;
 		try {
-			digest = MessageDigest.getInstance("MD5");
+			MessageDigest md = MessageDigest.getInstance("MD5");
-		}
+			InputStream is = Files.newInputStream(Paths.get(path_of_file_));
-		catch (NoSuchAlgorithmException e1) {
+			DigestInputStream dis = new DigestInputStream(is, md);
-			e1.printStackTrace();
-			return "";
-		}
-		File f = new File(path_of_file_);
-		InputStream is;
-		try {
-			is = new FileInputStream(f);
-		}
-		catch (FileNotFoundException e1) {
-			e1.printStackTrace();
-			return "";
-		}
 			byte[] buffer = new byte[8192];
-		int read = 0;
+			while (dis.read(buffer) > 0)
-		try {
+				; // process the entire file
-			while ((read = is.read(buffer)) > 0) {
+			return DatatypeConverter.printHexBinary(md.digest()).toLowerCase();
-				digest.update(buffer, 0, read);
-			}
-			byte[] md5sum = digest.digest();
-			BigInteger bigInt = new BigInteger(1, md5sum);
-			
-			String output = bigInt.toString(16);
-			
-			// fill with "0" because bigInt.toString does not add 0 at the beginning of the result
-			int zero_to_add = 32 - output.length();
-			for (int i = 0; i < zero_to_add; i++)
-				output = "0" + output;
-			
-			return output;
-		}
-		catch (IOException e) {
-			e.printStackTrace();
-		}
-		finally {
-			try {
-				is.close();
-			}
-			catch (IOException e) {
-				e.printStackTrace();
-				//throw new RuntimeException("Unable to close input stream for MD5 calculation", e);
-			}
 		}
+		catch (NoSuchAlgorithmException | IOException e) {
 			return "";
 		}
+	}
 	
 	public static double lastModificationTime(File directory_) {
 		double max = 0.0;