Question

Your task is to write a multithreaded program (using persistent threads) for calculating and printing out the MD5 hash values of the files in a directory (or a even a single file). Your program should accept as a command-line parameter the directory to examine. Example: $ ./dirHash Documents You should use the producer-consumer pattern for setting-up the communication between your main and your worker threads.

using java

Answer 1

here is the sample code for generating the MD5 for files present in any given directory.

procedure :

1) First, get the list of all files present in the directory.

2) Then we have a function called convertFileToMD5() for generating MD5.

3) Input for this can be a file path for directory path, if it is a file path, then it will directly generate the md5 values for the file and for the directory it will generate the md5 values for all files present.

code:

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.util.ArrayList;
import java.util.Scanner;

public class createMd5 {
   public static String convertFileToMD5(String filePath) {
       InputStream inputStream = null;
       try {
           inputStream = new FileInputStream(filePath);
           byte[] buffer = new byte[1024];
           MessageDigest digest = MessageDigest.getInstance("MD5");
           int numRead = 0;
           while (numRead != -1) {
               numRead = inputStream.read(buffer);
               if (numRead > 0)
                   digest.update(buffer, 0, numRead);
           }
           byte[] md5Bytes = digest.digest();
           return convertHashToString(md5Bytes);
       } catch (Exception e) {
           return null;
       } finally {
           if (inputStream != null) {
               try {
                   inputStream.close();
               } catch (Exception e) {
               }
           }
       }
   }

   private static String convertHashToString(byte[] md5Bytes) {
       String returnVal = "";
       for (int i = 0; i < md5Bytes.length; i++) {
           returnVal += Integer.toString((md5Bytes[i] & 0xff) + 0x100, 16)
                   .substring(1);
       }
       return returnVal.toUpperCase();
   }

   private static ArrayList<String> getAllFilePath(String dir)
           throws IOException {
       File folder = new File(dir);
       File[] listOfFiles = folder.listFiles();
       ArrayList<String> filePaths = new ArrayList();
       for (int i = 0; i < listOfFiles.length; i++) {
           if (listOfFiles[i].isFile()) {
               filePaths.add(listOfFiles[i].getCanonicalPath());
           } else if (listOfFiles[i].isDirectory()) {
           }
       }

       return filePaths;
   }

   public static void main(String[] args) {
       Scanner s = new Scanner(System.in);
       System.out.println("Enter the path for directory:");
       String path;
       path = s.next();
       try {

           File givenPathFile = new File(path);
           if (givenPathFile.isDirectory()) {
               ArrayList<String> filePaths = getAllFilePath(path);
               for (int i = 0; i < filePaths.size(); i++) {

                   String md5 = convertFileToMD5(filePaths.get(i));
                   if (md5 != null)
                       {
                       System.out.println("file:"+filePaths.get(i)+"\nMD5:"+md5);
                       }
                   else
                       System.out.println("Not valid path");

               }
           } else {
               String md5 = convertFileToMD5(givenPathFile.getCanonicalPath());
               if (md5 != null)
                   System.out.println("file:"+givenPathFile.getCanonicalPath()+"\nMD5:"+md5);
               else
                   System.out.println("Not valid path");
           }

       } catch (Exception e) {
           e.printStackTrace();
           System.out.println("Not valid path");
       }
   }
}