Date、String、Calendar类型之间的转化

1.Calendar 转化 String

//获取当前时间的具体情况,如年,月,日,week,date,分,秒等

Calendar calendat = Calendar.getInstance();

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

String dateStr = sdf.format(calendar.getTime());

2.String 转化Calendar

String str="2010-5-27";

SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");

Date date =sdf.parse(str);

Calendar calendar = Calendar.getInstance();

calendar.setTime(date);

3.Date 转化String

SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");

String dateStr=sdf.format(new Date());

4.String 转化Date

String str="2010-5-27";

SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");

Date birthday = sdf.parse(str);

5.Date 转化Calendar

Calendar calendar = Calendar.getInstance();

calendar.setTime(new java.util.Date());

6.Calendar转化Date

Calendar calendar = Calendar.getInstance();

java.util.Date date =calendar.getTime();

下面有个例子，插入oralce表类型为DATE的数据

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd HHmmss");

String date = sdf.format(new Date());

-----------------------------------------

String sql = "Insert into SM_SEND (*****************) " +

"values (*******************************

"',1," + "to_date('" +date+ "','YYYY-MM-DD HH24:MI:SS')" +

"," + "to_date('" +date+ "','YYYY-MM-DD HH24:MI:SS')" +

",0,null,null,null,null,null,null,null)";

注：date转calendar时使用calendar.setTime();

有时当setTime的参数格式问题会导致转换异常

实例 1

/**
     * 获取上月十五日凌晨时间
     * @author:  WY
     * @rise:
     */
    public static String previousMonth15() throws ParseException{
        
        Calendar calendar = Calendar.getInstance();
        
        calendar.set(Calendar.MONTH, calendar.get(Calendar.MONTH)-1);
        calendar.set(Calendar.DAY_OF_MONTH,15);
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.SECOND,0);
        calendar.set(Calendar.MINUTE,0);
        
        Date strDateTo = calendar.getTime();      
        SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        
        return     sdf.format(strDateTo);
    }