工作中时可能会遇到需要循环查询一年相关历史表的业务；
如何获取12个年月信息：

	@Test
	public void mian() throws Exception{
		Calendar c = Calendar.getInstance();
		//取当前时间12个月内的年月
		for(int i = 0; i < 12; i ++){
			int k = c.get(Calendar.YEAR);
			int j = c.get(Calendar.MONTH) + 1 - i;
			String date = "";
			if(j >= 1){
				date = k + (j >= 10 ? "" : "0") + j;
			} else {
				int p = 11 - i;
				int m = c.get(Calendar.YEAR) - 1;
				int n = c.get(Calendar.MONTH) + 2 + p;
				date = m + (n >= 10 ? "" : "0") + n;
			}
			System.out.println(date);
		}
	}

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Calendar c = Calendar.getInstance();
         
        //过去七天
        c.setTime(new Date());
        c.add(Calendar.DATE, - 7);
        Date d = c.getTime();
        String day = format.format(d);
        System.out.println("过去七天："+day);
         
        //过去一月
        c.setTime(new Date());
        c.add(Calendar.MONTH, -1);
        Date m = c.getTime();
        String mon = format.format(m);
        System.out.println("过去一个月："+mon);
         
        //过去三个月
        c.setTime(new Date());
        c.add(Calendar.MONTH, -3);
        Date m3 = c.getTime();
        String mon3 = format.format(m3);
        System.out.println("过去三个月："+mon3);
         
        //过去一年
        c.setTime(new Date());
        c.add(Calendar.YEAR, -1);
        Date y = c.getTime();
        String year = format.format(y);
        System.out.println("过去一年："+year);