Generate the sha1 hash code of a file

FileSHA1Code.java

package com.zeroleaf.util;

import java.io.FileInputStream;
import java.io.IOException;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * User: zeroleaf
 * Date: 13-10-3
 * Time: 21:04
 *
 * Generate a sha1 hash code of a file.
 */
public class FileSHA1Code {

    public static void main(String[] args) throws IOException, NoSuchAlgorithmException {
        FileSHA1Code fileHash = new FileSHA1Code();
        System.out.println(fileHash.sha1Code("testfile.txt"));

        /*
         * Input file name: testfile.txt
         * Input file content: (only one line bellow)
         * This is a file for test sha1 hash code
         *
         * Output:
         * 7465503EADC8799AE6F64E03EE87AB747B9D08F5
         *
         */
    }

    /**
     * Generate a file 's sha1 hash code.
     * @param filePath file path
     * @return sha1 hash code of this file
     * @throws IOException if file doesn't or other IOException
     * @throws NoSuchAlgorithmException
     */
    public String sha1Code(String filePath) throws IOException, NoSuchAlgorithmException {
        FileInputStream fileInputStream = new FileInputStream(filePath);
        MessageDigest digest = MessageDigest.getInstance("SHA-1");
        DigestInputStream digestInputStream = new DigestInputStream(fileInputStream, digest);
        byte[] bytes = new byte[1024];
        // read all file content
        while (digestInputStream.read(bytes) > 0);

//        digest = digestInputStream.getMessageDigest();
        byte[] resultByteArry = digest.digest();
        return bytesToHexString(resultByteArry);
    }

    /**
     * Convert a array of byte to hex String. <br/>
     * Each byte is covert a two character of hex String. That is <br/>
     * if byte of int is less than 16, then the hex String will append <br/>
     * a character of '0'.
     *
     * @param bytes array of byte
     * @return hex String represent the array of byte
     */
    public static String bytesToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            int value = b & 0xFF;
            if (value < 16) {
                // if value less than 16, then it's hex String will be only
                // one character, so we need to append a character of '0'
                sb.append("0");
            }
            sb.append(Integer.toHexString(value).toUpperCase());
        }
        return sb.toString();
    }
}