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()); 
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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)";