@Test
public void papapa() {
String formateD = "yyyy年MM月dd日";
SimpleDateFormat sdf = new SimpleDateFormat(formateD);
try {
Date date = new SimpleDateFormat(formateM).parse("2018-04");
Calendar cal = Calendar.getInstance();
String monthEnd, monthStart;
//将传入的时间年月 转给cal对象
cal.setTime(date);
//在这个时间基础上设置为这个月的第一天
cal.add(Calendar.MONTH, 0);
cal.set(Calendar.DAY_OF_MONTH, 1);
//获取这个格式的第一天
monthStart = sdf.format(cal.getTime());
cal.add(Calendar.MONTH, 1);
cal.set(Calendar.DAY_OF_MONTH, 0);
//获取这个月的最后一天
monthEnd = sdf.format(cal.getTime());
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}