SimpleDateFormat format = 

new 

SimpleDateFormat(

"yyyy-MM-dd"

); 

          

        

//获取前月的第一天

        

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);

        

//获取前月的最后一天

        

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);

          

          

        

//获取当前月第一天：

        

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 = format.format(c.getTime());

        

System.out.println(

"===============first:"

+first);

          

        

//获取当前月最后一天

        

Calendar ca = Calendar.getInstance();    

        

ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));  

        

String last = format.format(ca.getTime());

        

System.out.println(

"===============last:"

+last);

         

        

/** 

     

* 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)); 

    

}