dateutil.java

Struts入门的一个好例子 Struts入门的一个好例子

package bily.notebook.util;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class DateUtil {
	
	public static final int _Year = 1;
	public static final int _Month = 2;
	public static final int _Date = 3;

	public static boolean isDate(String str) {
		
		if (StringUtil.isEmpty(str)) return false;
		if (str.length() != 8 && str.length() != 10) return false;
		if (str.length() == 10) {
			str = str.substring(0,4) + str.substring(5,7) + str.substring(8,10);
		}
		try {
			SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
			sdf.parse(str);
		} catch (Exception e) {
			return false;
		}
		return true;
	}

	public static Date getDateFromString(String str) throws Exception {
		if (StringUtil.isEmpty(str)) return null;
		if (str.length() != 8 && str.length() != 10) return null;
		if (str.length() == 10) {
			str = str.substring(0,4) + str.substring(5,7) + str.substring(8,10);
		}
		try {
			SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
			return sdf.parse(str);
		} catch (Exception e) {
			return null;
		}
	}
	
	public static String getStringFromDate(Date date, String format) {
		SimpleDateFormat sdf = new SimpleDateFormat(format);
		return sdf.format(date);
	}
	
    public static Date moveToDate(int flg, Date date, int count) {
        Calendar calendar = Calendar.getInstance();
        try {
            calendar.setTime(date);
            switch(flg) {
            case _Year: 
            	calendar.add(Calendar.YEAR, count);
            case _Month:
            	calendar.add(Calendar.MONTH, count);
            case _Date:
            	calendar.add(Calendar.DATE, count);
            }            
            return calendar.getTime();
        } catch (Exception e) {
            return null;
        }
    }
	
	
}