java日期互转

import java.sql.Timestamp;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * String Date Calendar之间的转换
 */
public class DateTransform {
    /**
     * Calendar 转 String
     * @param c Calendar
     * @param dateFormatStr 如"yyyy-MM-dd"
     * @return
     */
    public String calendar2String(Calendar c, String dateFormatStr) {
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormatStr);
        return sdf.format(c.getTime());
    }

    /**
     * String转Calendar
     * @param dateStr
     * @param dateFormatStr 如"yyyy-MM-dd"
     * @return
     */
    public Calendar string2Calendar(String dateStr, String dateFormatStr) throws ParseException {
        SimpleDateFormat sdf= new SimpleDateFormat(dateFormatStr);
        Date date =sdf.parse(dateStr);
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar;
    }

    /**
     * Date转String
     * @param date
     * @param dateFormatStr 如"yyyy-MM-dd"
     * @return
     */
    public String date2String(Date date, String dateFormatStr) {
        SimpleDateFormat sdf= new SimpleDateFormat(dateFormatStr);
        return sdf.format(date);
    }

    /**
     * String转Date
     * @param dateStr
     * @param dateFormatStr 如"yyyy-MM-dd"
     * @return
     */
    public Date string2Date(String dateStr, String dateFormatStr) throws ParseException {
        SimpleDateFormat sdf= new SimpleDateFormat(dateFormatStr);
        return sdf.parse(dateStr);
    }

    /**
     * Date转Calendar
     * @param date
     * @return
     */
    public Calendar date2Calendar(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar;
    }

    /**
     * Calendar转Date
     * @param c
     * @return
     */
    public Date calendar2Date(Calendar c) {
        return c.getTime();
    }

    /**
     * String转Timestamp
     * @param dateStr
     * @return
     */
    public Timestamp string2Timestamp(String dateStr) {
        return Timestamp.valueOf(dateStr);
    }

    /**
     * Date转Timestamp
     * @param date
     * @param dateFormatStr 如"yyyy-MM-dd"
     * @return
     */
    public Timestamp date2Timestamp(Date date, String dateFormatStr) {
        SimpleDateFormat df = new SimpleDateFormat(dateFormatStr);
        String time = df.format(date);
        return Timestamp.valueOf(time);
    }

}