Java Calendar对象获取本月或者上月的第一天和最后一天

有些sql查询的需要。
直接上代码：

    public static void main(String[] args) {
        //获取前月的最后一天
        Calendar cale1= Calendar.getInstance();
   	    cale1.add(Calendar.MONTH, -1);
   	    cale1.set(Calendar.DAY_OF_MONTH,1);
   	    cale1.set(Calendar.HOUR_OF_DAY,0);
   	    cale1.set(Calendar.SECOND,0);
   	    cale1.set(Calendar.MINUTE,0);
   	    System.out.println("-----1------firstDay:"+ cale1.getTimeInMillis()/1000);
   	    //获取前月的最后一天
        Calendar cale2 = Calendar.getInstance();
        cale2.set(Calendar.DAY_OF_MONTH,0);
        cale2.set(Calendar.HOUR_OF_DAY,23);
        cale2.set(Calendar.SECOND,59);
        cale2.set(Calendar.MINUTE,59);
        System.out.println("-----2------lastDay:"+cale2.getTimeInMillis()/1000);

运行效果：

时间戳转换一下：2019-11-1 00:00:00 ~ 2019-11-30 23:59:59

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 

最后一天：

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

时分秒这些设置如上