44.Android MD5Util

public class MD5Util {    public static String getMD5String(String key) {        char hexDigits[] = {
     '0', '1', '2', '3', '4',                '5', '6', '7', '8', '9',                'A', 'B', 'C', 'D', 'E', 'F'};        try {            byte[] input = key.getBytes();            // MD5算法的 MessageDigest 对象            MessageDigest md5Digest = MessageDigest.getInstance("MD5");            // 转换            md5Digest.update(input);            // 密文            byte[] md5byte = md5Digest.digest();            // string 转 十六进制            int j = md5byte.length;            char md5char[] = new char[j * 2];            int k = 0;            for (byte b : md5byte) {                md5char[k++] = hexDigits[b >>> 4 & 0xf];                md5char[k++] = hexDigits[b & 0xf];            }            return new String(md5char);        } catch (Exception e) {            e.printStackTrace();            return null;        }    }    private static String bytesToHexString(byte[] bytes) {        StringBuilder sb = new StringBuilder();        for (byte aByte : bytes) {            String hex = Integer.toHexString(255 & aByte);            if (hex.length() == 1) {                sb.append('0');            }            sb.append(hex);        }        return sb.toString();    }}