获取当前月 下月 下下月 的第一天和最一天

Calendar c = Calendar.getInstance();//可以对每个时间域单独修改

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd 00:00:00");
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd 23:59:59");

//获取当前月第一天：
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 = sdf.format(c.getTime());
//获取当前月最后一天
c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));
String last = sdf.format(c.getTime());

//上个月
c.add(Calendar.MONTH, -1);
//设置为1号,当前日期既为上月第一天 
c.set(Calendar.DAY_OF_MONTH,1);
String t = sdf.format(c.getTime());

//获取上个月的最后一天
Calendar call = Calendar.getInstance();
//设置上个月最后一天
call.set(Calendar.DAY_OF_MONTH,0);
String t2 = sdf2.format(call.getTime());

//上上个月
Calendar call = Calendar.getInstance();
call.add(Calendar.MONTH, -2);
//设置为1号
call.set(Calendar.DAY_OF_MONTH,1);
String t = sdf.format(call.getTime());
//获取上上个月的最后一天
//设置上上个月最后一天
int maxCurrentMonthDay=call.getActualMaximum(Calendar.DAY_OF_MONTH);
call.set(Calendar.DAY_OF_MONTH,maxCurrentMonthDay);
String t2 = sdf2.format(call.getTime());