第一个,计算字符串的md5值

public static String getMD5(String s){        String newString  = null;        byte[] inputByteArray = s.getBytes();        char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',                'A', 'B', 'C', 'D', 'E', 'F' };        try {            MessageDigest md = MessageDigest.getInstance("MD5");            md.update(inputByteArray);            byte[] mdByte = md.digest();            int j = mdByte.length;            char str[] = new char[j * 2];            int k = 0;            for (int i = 0; i < j; i++) {                byte byte0 = mdByte[i];                str[k++] = hexDigits[byte0 >>> 4 & 0xf];                str[k++] = hexDigits[byte0 & 0xf];            }            newString = new String(str);        } catch (Exception e) {            e.printStackTrace();        }        return newString;    }

第二个,计算文件(给出路径)的md5值

public static String getFileMd5(String path) {        try {                        File file = new File(path);            // md5            MessageDigest digest = MessageDigest.getInstance("md5");            FileInputStream fis = new FileInputStream(file);            byte[] buffer = new byte[1024];            int len = -1;            while ((len = fis.read(buffer)) != -1) {                digest.update(buffer, 0, len);            }            byte[] result = digest.digest();            StringBuffer sb = new StringBuffer();            for (byte b : result) {                                int number = b & 0xff;//避免byte转int时出现负数                String str = Integer.toHexString(number);                // System.out.println(str);                if (str.length() == 1) {                    sb.append("0");                }                sb.append(str);            }            return sb.toString();        } catch (Exception e) {            e.printStackTrace();            return "";        }    }