String、Calendar、Date间的相互转换（收藏）

引言：

      常见的string，calendar，Date之间的转换，值得收藏哦

代码如下：

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 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();
7.Date 转成 String

System.out.println(sdf.format(new Date()));
8.String 转成 Timestamp

Timestamp ts = Timestamp.valueOf("2011-1-14 08:11:00");
8.String 转成 Timestamp

Timestamp ts = Timestamp.valueOf("2011-1-14 08:11:00");
9.Timestamp 转成 String

sdf.format(ts);
Timestamp 和 Date 多数用法是一样的。

10.Date 转 TimeStamp

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

String time = df.format(new Date());

Timestamp ts = Timestamp.valueOf(time);
11.日期比较大小

String ti="2010-11-25 20:11:00";

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

Date time=sdf.parse(ti);

String ti2="2011-11-26 20:11:00";

Date time2=sdf.parse(ti2);

int c=ti2.compareTo(ti);

if(c>0){

System.out.println(ti+"大");

}else if(c==0){

System.out.println("一样大");

}else{

System.out.println(ti2+"大");

}
12.Date/ Timestamp 转成 Calendar

Calendar calendar = Calendar.getInstance();

calendar.setTime(startDate);

calendar.add(Calendar.YEAR, 2);   //日期加 2 年

System.out.println(calendar.getTime());

calendar.add(Calendar.DATE, -30);     //日期加 30 天

System.out.println(calendar.getTime());

calendar.add(Calendar.MONTH, 3);  //日期加 3 个月

System.out.println(calendar.getTime());
Date date=new Date();

DateFormat df=DateFormat.getDayeInstance();

ps.setString(4,df.format(date))
Date date = new Date();

SimpleDateFormat from = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

String times = from.format(date);
public class Test1 {

public static void main(String[] args) {

long   m=System.currentTimeMillis();

System.out.println(new Date(m) );

}