時間轉換小工具類

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
/**
 * 時間轉換工具類
 */
public class DateTool {
	/**
	 * 獲取當前時間格式是：yyyy-MM-dd HH:mm:ss
	 * @return
	 */
	public static String getDate(){
		return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
	}
	/*
	 * 獲取當前時間格式是：yyyy-MM-dd
	 */
	public static String getDay(){
		return new SimpleDateFormat("yyyy-MM-dd").format(new Date());
	}
	/**
	 * 獲取輸入時間的前多少月
	 * @param time 
	 * @param storageTime
	 * @return
	 */
	public static String convertDate(String time,String storageTime){
		SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date date;
		try {
			date = sdf.parse(time);
			Calendar rightNow = Calendar.getInstance();
			rightNow.setTime(date);
			rightNow.add(Calendar.MONTH, - Integer.parseInt(storageTime));
			return sdf.format(rightNow.getTime());
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return null;
	}
	/**
	 * 獲取輸入時間的後多少月
	 * @param time 
	 * @param storageTime
	 * @return
	 */
	public static String convertDay(String time,String storageTime){
		SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
		Date date;
		try {
			date = sdf.parse(time);
			Calendar rightNow = Calendar.getInstance();
			rightNow.setTime(date);
			rightNow.add(Calendar.MONTH,Integer.parseInt(storageTime));
			return sdf.format(rightNow.getTime());
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return null;
	}
}