root/server/OverhaulFile.java

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Vector;

public class OverhaulFile {

        private int numChunks;
        private int chunkSize;
        private int maxClients;
        private int lastChunk;
        private Vector<String> md5List;
        
        public OverhaulFile() {
                lastChunk = 0;
                md5List = new Vector<String>();
        }

        public synchronized String getMd5ListStr() {
                
                String ret = "";
                for(int i = 0; i < md5List.size(); i++) {
                        if (i != 0) {
                                ret += " ";
                        }
                        ret += md5List.get(i);
                }
                
                return ret;
        }
        
        public synchronized void setMd5List(File target) {
                try {
                        InputStream is = new FileInputStream(target.getAbsolutePath());
                        for (int i = 1; i <= numChunks; i++) {

                                int startByte = (i - 1) * chunkSize;
                                int endByte = Math.min(i * chunkSize, (int) target.length());
                                int bytesToRead = endByte - startByte;
                                                        
                                byte[] buf= new byte[bytesToRead];
                                int n = is.read(buf);
                                if (n != bytesToRead) {
                                        // oops
                                        System.out.println("(-----(MD5)-----) Supposed to read: " + bytesToRead + " bytes, read: " + n + "bytes");
                                        System.out.println("i=" +i + "; startByte=" + startByte + "; endByte=" + endByte);
                                }
                                
                                String checkSum = generateCheckSum(buf);
                                md5List.add(checkSum);
                        }
                } catch (Exception e) {
                        
                }
        }


        //public void setClients(Vector<InetAddress> clients) {
        //      this.clients = clients;
        //}
        
        public synchronized int getLastChunk() {
                return lastChunk;
        }

        public synchronized void setLastChunk(int lastChunk) {
                this.lastChunk = lastChunk;
        }
        
        public static String generateCheckSum(byte data[]) {
        String hashword;
        MessageDigest md = null;

        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }

        md.update(data);
        BigInteger hash = new BigInteger(1, md.digest());
        hashword = hash.toString(16);

        // prepend with 0s if hash string length less then 32
        if (hashword.length() < 32) {
            int zeros = 32 - hashword.length();
            for (int i = 0; i < zeros; i++) {
                hashword = "0" + hashword;
            }
        }

        //System.out.println("Digest: " + hashword + "\n");

        return hashword;
    }

        public synchronized int getChunkSize() {
                return chunkSize;
        }

        public synchronized void setChunkSize(int chunkSize) {
                this.chunkSize = chunkSize;
        }

        public int getNumChunks() {
                return numChunks;
        }

        public void setNumChunks(int numChunks) {
                this.numChunks = numChunks;
        }

        public int getMaxClients() {
                return maxClients;
        }

        public void setMaxClients(int maxClients) {
                this.maxClients = maxClients;
        }
}