Java計算字符串和文件的MD5與SHA1

package net.hkh.util;

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

public class MD5Utils {
	@SuppressWarnings("unused")
	private static final String md5 = "MD5";
	@SuppressWarnings("unused")
	private static final String sha1 = "SHA-1";

	/**
	 * @desc 計算字符串的md5 or sha1
	 * @param str
	 * @param lx,md5
	 *            or sha1
	 * @return
	 * @throws UnsupportedEncodingException
	 * 
	 */
	public static String md5OrSha1OfString(String str, String lx)
			throws UnsupportedEncodingException {
		try {
			MessageDigest md = MessageDigest.getInstance(lx);
			byte[] inputByteArr = str.getBytes("UTF-8");
			md.update(inputByteArr);
			byte[] rsByteArr = md.digest();
			return byteArrayToHex(rsByteArr);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			return null;
		}
	}

	/**
	 * @desc 計算文件的md5 or sha1
	 * @param inputFile
	 * @param lx,md5
	 *            or sha1
	 * @return
	 * @throws IOException
	 * 
	 */
	@SuppressWarnings("finally")
	public static String md5OrSha1OfFile(String inputFile, String lx)
			throws IOException {
		int bufferSize = 256 * 1024;
		FileInputStream fis = null;
		DigestInputStream dis = null;
		String rslt = null;
		try {
			MessageDigest md = MessageDigest.getInstance(lx);
			fis = new FileInputStream(inputFile);
			dis = new DigestInputStream(fis, md);
			byte[] buffer = new byte[bufferSize];
			while (dis.read(buffer) > 0) {
				md = dis.getMessageDigest();
				byte[] arr = md.digest();
				rslt = byteArrayToHex(arr);
			}
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			rslt = null;
		} finally {
			try {
				dis.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
			dis = null;
			try {
				fis.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
			fis = null;
			return rslt;
		}
	}

	/**
	 * @desc 將生成的字節數組轉化爲十六進制字符串
	 * @param arr
	 * @return
	 * 
	 */
	public static String byteArrayToHex(byte[] arr) {
		String hexStr = "0123456789ABCDEF";
		StringBuilder rslt = new StringBuilder();
		for (int i = 0; i < arr.length; i++) {
			rslt.append(String.valueOf(hexStr.charAt((arr[i] & 0xf0) >> 4)));
			rslt.append(String.valueOf(hexStr.charAt(arr[i] & 0x0f)));
		}
		return rslt.toString();
	}
	
}