部分文字列を取り出す

private String getCutString(String str, String start, String end) throws Exception {
  String rtnStr = "";

  int pos1, pos2;
  pos1 = str.indexOf(start);
  if (!end.equals("")) {
    pos2 = str.indexOf(end, pos1);
    rtnStr = str.substring(pos1 + start.length(), pos2);
  } else {
    rtnStr = str.substring(pos1 + start.length());
  }

  return rtnStr;
}