Jmeter-日期格式转换为时间戳

//将日期格式转换为时间戳
String begin = vars.get("first");
String end =  vars.get("last");
Date beginTime1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(begin);
Date endTime1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(last);
String beginTime = String.valueOf(beginTime1.getTime());
String endTime = String.valueOf(endTime1.getTime());
vars.put("beginTime",beginTime);
vars.put("endTime",endTime);