java 日期计算工具类小结

骑猪看日落 2021-06-24 14:00 564阅读 0赞

1、本周第一天：

public static Date getStartTime4Week() throws Exception{  
        	//SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");  
        	Calendar cal = Calendar.getInstance();
        	int day_of_week = cal.get(Calendar.DAY_OF_WEEK) - 2;
        	cal.add(Calendar.DATE, -day_of_week);
        	/*String startTT = df.format(cal.getTime());
        	System.out.println("本周第一天: " + startTT);*/
        	return cal.getTime();
    }

2、本周最后一天：

public static Date getEndTime4Week() throws Exception{  
        	//SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");  
        	Calendar cal = Calendar.getInstance();
        	int day_of_week = cal.get(Calendar.DAY_OF_WEEK) - 2;
        	cal.add(Calendar.DATE, -day_of_week);
        	cal.add(Calendar.DATE, 6);
        	/*String startTT = df.format(cal.getTime());
        	System.out.println("本周第一天: " + startTT);*/
        	return cal.getTime();
    }

3、本月第一天：

public static Date getStartTime4Month() throws Exception{  
        	//SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");
        	Calendar c = Calendar.getInstance();    
            c.add(Calendar.MONTH, 0);
            c.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天 
            //String first = df.format(c.getTime());
            //System.out.println("===============first:"+first);
            return c.getTime();
    }

4、本月最后一天：

public static Date getEndTime4Month() throws Exception{  
        	//SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");  
        	Calendar ca = Calendar.getInstance();    
            ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));  
            //String last = df.format(ca.getTime());
            //System.out.println("===============last:"+last);
        	/*String startTT = df.format(cal.getTime());
        	System.out.println("本周第一天: " + startTT);*/
        	return ca.getTime();
    }

5、上月第一天：

<pre name="code" class="java">public static Date getStartTime4PreMonth() throws Exception{

<pre name="code" class="java">        Calendar   cal_1=Calendar.getInstance();//获取当前日期 
            cal_1.add(Calendar.MONTH, -1);
            cal_1.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天 
            firstDay = format.format(cal_1.getTime());
            System.out.println("-----1------firstDay:"+firstDay);

return cal\_1.getTime(); \}

6、上月最后一天：

<pre name="code" class="java"><pre name="code" class="java">public static Date getStartTime4PreMonth() throws Exception{<span style="font-family: Arial, Helvetica, sans-serif;">       </span>

<pre name="code" class="java"><pre name="code" class="java">        Calendar cale = Calendar.getInstance();   
            cale.set(Calendar.DAY_OF_MONTH,0);//设置为1号,当前日期既为本月第一天 
            lastDay = format.format(cale.getTime());
            System.out.println("-----2------lastDay:"+lastDay);

return cale.getTime();

}

7、计算两个日期之间相差的天数 ：

public static int daysBetween(Date smdate,Date bdate) throws ParseException{    
            SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");  
            smdate=sdf.parse(sdf.format(smdate));  
            bdate=sdf.parse(sdf.format(bdate));  
            Calendar cal = Calendar.getInstance();    
            cal.setTime(smdate);    
            long time1 = cal.getTimeInMillis();                 
            cal.setTime(bdate);    
            long time2 = cal.getTimeInMillis();         
            long between_days=(time2-time1)/(1000*3600*24);  
                
           return Integer.parseInt(String.valueOf(between_days));           
        }

8、字符串的日期格式的计算：

public static int daysBetween(String smdate,String bdate) throws ParseException{  
            SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");  
            Calendar cal = Calendar.getInstance();    
            cal.setTime(sdf.parse(smdate));    
            long time1 = cal.getTimeInMillis();                 
            cal.setTime(sdf.parse(bdate));    
            long time2 = cal.getTimeInMillis();         
            long between_days=(time2-time1)/(1000*3600*24);  
                
           return Integer.parseInt(String.valueOf(between_days));     
    }

9、本季度第一天：

public static Date getStartTime4Quart() throws Exception{ 
        	SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");  
        	Calendar c = Calendar.getInstance();
            int currentMonth = c.get(Calendar.MONTH) + 1;
            try {
                if (currentMonth >= 1 && currentMonth <= 3)
                    c.set(Calendar.MONTH, 0);
                else if (currentMonth >= 4 && currentMonth <= 6)
                    c.set(Calendar.MONTH, 3);
                else if (currentMonth >= 7 && currentMonth <= 9)
                    c.set(Calendar.MONTH, 4);
                else if (currentMonth >= 10 && currentMonth <= 12)
                    c.set(Calendar.MONTH, 9);
                c.set(Calendar.DATE, 1);
                System.out.println(df.format(c.getTime()));
            } catch (Exception e) {
                e.printStackTrace();
            }
            return c.getTime();
        }

10、本季度最后一天：

public static Date getEndTime4Quart() throws Exception{  
        	SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");  
        	Calendar c = Calendar.getInstance();
            int currentMonth = c.get(Calendar.MONTH) + 1;
            try {
                if (currentMonth >= 1 && currentMonth <= 3) {
                    c.set(Calendar.MONTH, 2);
                    c.set(Calendar.DATE, 31);
                } else if (currentMonth >= 4 && currentMonth <= 6) {
                    c.set(Calendar.MONTH, 5);
                    c.set(Calendar.DATE, 30);
                } else if (currentMonth >= 7 && currentMonth <= 9) {
                    c.set(Calendar.MONTH, 8);
                    c.set(Calendar.DATE, 30);
                } else if (currentMonth >= 10 && currentMonth <= 12) {
                    c.set(Calendar.MONTH, 11);
                    c.set(Calendar.DATE, 31);
                }
                System.out.println(df.format(c.getTime()));
            } catch (Exception e) {
                e.printStackTrace();
            }
            return c.getTime();
        }

11、本年第一天：

public static Date getStartTime4Year() throws Exception{ 
        	SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");  
        	Calendar c = Calendar.getInstance();
            try {
                c.set(Calendar.MONTH, 0);
                c.set(Calendar.DATE, 1);
                System.out.println(df.format(c.getTime()));
            } catch (Exception e) {
                e.printStackTrace();
            }
        	return c.getTime();
        }

12、本年最后一天：

public static Date getEndTime4Year() throws Exception{  
        	SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");  
        	Calendar c = Calendar.getInstance();
            try {
                c.set(Calendar.MONTH, 11);
                c.set(Calendar.DATE, 31);
                System.out.println(df.format(c.getTime()));
            } catch (Exception e) {
                e.printStackTrace();
            }
        	return c.getTime();
        }

13、求两个日期之间的每一天

/** 
         * 获得日期字符串数组 
         * @param calendarType 日期跨度的类型， 
         * */  
          
        public static Date[] getDateArrays(Date start,Date end ,int calendarType){  
            ArrayList<Date> ret = new ArrayList<Date>();  
            Calendar calendar = Calendar.getInstance();  
            calendar.setTime(start);  
            Date tmpDate = calendar.getTime();  
            long endTime = end.getTime();  
            while(tmpDate.before(end)||tmpDate.getTime() == endTime){  
                ret.add(calendar.getTime());  
                calendar.add(calendarType, 1);  
                tmpDate = calendar.getTime();  
            }         
              
            Date[] dates = new Date[ret.size()];  
            return ret.toArray(dates);        
        }  
      
    @Test  
        public void getDateArrays2(){  
            Date date = DateUtils.getDate("2008-04-01");  
            Date date2 = DateUtils.getDate("2008-08-01");  
            Date[] strArray = DateUtils.getDateArrays(date, date2, Calendar.DAY_OF_YEAR);  
            for (Date string : strArray) {  
                System.out.println(DateUtils.getDayStr(string));  
            }  
        }

注：SimpleDateFormat是线程不安全的，放到类变量中需要注意。

参考文章：http://www.cnblogs.com/GYoungBean/archive/2012/10/31/2748219.html