1 package com.test.packager;
2
3 import java.text.ParseException;
4 import java.text.SimpleDateFormat;
5 import java.util.Calendar;
6
7 public class Test {
8 private static String firstDay;
9 private static String lastDay;
10 public static void main(String[] args) {
11 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
12
13 //获取前月的第一天
14 Calendar cal_1=Calendar.getInstance();//获取当前日期
15 cal_1.add(Calendar.MONTH, -1);
16 cal_1.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天
17 firstDay = format.format(cal_1.getTime());
18 System.out.println("-----1------firstDay:"+firstDay);
19 //获取前月的最后一天
20 Calendar cale = Calendar.getInstance();
21 cale.set(Calendar.DAY_OF_MONTH,0);//设置为1号,当前日期既为本月第一天
22 lastDay = format.format(cale.getTime());
23 System.out.println("-----2------lastDay:"+lastDay);
24
25
26 //获取当前月第一天：
27 Calendar c = Calendar.getInstance();
28 c.add(Calendar.MONTH, 0);
29 c.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天
30 String first = format.format(c.getTime());
31 System.out.println("===============first:"+first);
32
33 //获取当前月最后一天
34 Calendar ca = Calendar.getInstance();
35 ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));
36 String last = format.format(ca.getTime());
37 System.out.println("===============last:"+last);
38
39 }
40 /**
41 * 字符串的日期格式的计算
42 */
43 public static int daysBetween(String smdate,String bdate) throws ParseException{
44 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
45 Calendar cal = Calendar.getInstance();
46 cal.setTime(sdf.parse(smdate));
47 long time1 = cal.getTimeInMillis();
48 cal.setTime(sdf.parse(bdate));
49 long time2 = cal.getTimeInMillis();
50 long between_days=(time2-time1)/(1000*3600*24);
51 return Integer.parseInt(String.valueOf(between_days));
52 }
53 }
