Java PHP MD5加密

public static String getMd5(byte[] buffer) throws NoSuchAlgorithmException{
    String s = null;
    char hexDigist[] = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
    MessageDigest md = MessageDigest.getInstance("MD5");
    md.update(buffer);
    byte[] datas = md.digest(); //16个字节的长整数
    char[] str = new char[2*16];
    int k = 0;
    for(int i=0;i<16;i++){
      byte b = datas[i];
      str[k++] = hexDigist[b>>>4 & 0xf];//高4位
      str[k++] = hexDigist[b & 0xf];//低4位
    }
    s = new String(str);
    return s;
  }