JAVA常用日期格式转换工具

package com.future.util;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

import org.apache.commons.lang.time.FastDateFormat;

/**
 * 日期工具
 * @author 
 *
 */
public class DateUtils {
	private static FastDateFormat formatter = FastDateFormat.getInstance("yyyy-MM-dd HH:mm:ss");
	private static DateFormat dateFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	private static DateFormat formatter1 = new SimpleDateFormat("yyyyMMdd");
	private static DateFormat formatter2 = new SimpleDateFormat("yyyy-MM-dd");
	private static SimpleDateFormat formatter3 = new SimpleDateFormat("yyyyMMddHHmmssSSS");
	private static DateFormat formatter4 = new SimpleDateFormat("MM-dd");
	public static final SimpleDateFormat date_sdf = new SimpleDateFormat(
			"yyyy-MM-dd");
	public static final  SimpleDateFormat datetimeFormat = new SimpleDateFormat(
			"yyyy-MM-dd HH:mm:ss");
	
	private static Calendar gregorianCalendar = null;
	
	/**
	 * 日期转字符串(yyyy-MM-dd HH:mm:ss)
	 * @param date
	 * @return
	 */
	public static String format(Date date){
		return formatter.format(date);
	}
	
	/**
	 * 日期转字符串(yyyyMMdd)
	 * @param date
	 * @return
	 */
	public static String formatDate(Date date){
		return formatter1.format(date);
	}
	
	/**
	 * 日期转字符串(yyyyMMdd)
	 * @param date
	 * @return
	 */
	public static String formatDate2(Date date){
		return formatter2.format(date);
	}
	/**
	 * 字符串转日期
	 * @param date
	 * @return
	 * @throws ParseException
	 */
	public static Date parse(String date) throws ParseException {
		return dateFormatter.parse(date);
	}
	
	/**
	 * 按照指定格式进行字符串转日期
	 * @param str
	 * @param sdf
	 * @return
	 */
	public static Date str2Date(String str, SimpleDateFormat sdf) {
		if (null == str || "".equals(str)) {
			return null;
		}
		Date date = null;
		try {
			date = sdf.parse(str);
			return date;
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return null;
	}
	
	 /**
     * 将sql date 转为 字符串
     * 
     * @param date
     * @return
     */
    public static String sql2str(java.sql.Date date) {
        if (date == null) {
            return "";
        }
        return formatter2.format(date);
    }
	

	
	public static String getNowDate(){
		return formatter3.format(new Date());
	}
	
	/**
	 * 提供日志产生的时间
	 * @return
	 */
	public static String logDate(){
		return "[" + format(new java.util.Date()) + "]: ";
	}
	/**
	 * 获取当前月的最后一天
	 * @param date
	 * @return
	 */
	public static String lastDayOfMonth(Date date) { 
		gregorianCalendar = new GregorianCalendar();
		gregorianCalendar.setTime(date); 
		gregorianCalendar.set(Calendar.DAY_OF_MONTH, 1); 
		gregorianCalendar.roll(Calendar.DAY_OF_MONTH, -1); 
		return formatter2.format(gregorianCalendar.getTime());
	} 
	/**
	 * 获取当前月的第一天
	 * @return
	 */
	public static String getFirstDay(Date date) {
		gregorianCalendar = new GregorianCalendar();
		gregorianCalendar.setTime(date);
		gregorianCalendar.add(Calendar.MONTH, 0);
		gregorianCalendar.set(Calendar.DAY_OF_MONTH, 1);
		return formatter2.format(gregorianCalendar.getTime());
	  }
	/** 
	* 
	* @Description:判断时间点是否在时间点之前 
	* 如果此 firstDate 的时间在参数表示的时间之前，则返回小于 0 的值 
	* @param firstDate 
	* @param secondDate 
	* @return 
	* @ReturnType boolean 
	* @author: 
	* @Created 2012 2012-9-20上午08:40:33 
	*/ 
	public static boolean isBefore(Date firstDate, Date secondDate) { 

	  return compare(firstDate, secondDate) < 0 ? true : false; 
	} 
	   /** 
	    * 
	    * @Description:判断时间点是否在时间点之后 
	    * 如果此 firstDate 的时间在参数表示的时间之后，则返回大于 0 的值 
	    * @param firstDate 
	    * @param secondDate  
	    * @ReturnType boolean 
	    * @author: 
	    * @Created 2012 2012-9-20上午08:38:48 
	    */ 
	public static boolean isAfter(Date firstDate, Date secondDate) { 

	  return compare(firstDate, secondDate) > 0 ? true : false; 
	} 
	/** 
	* 
	* @Description:比较两个时间点是否相等 
	* @param firstDate 
	* @param secondDate 
	* @ReturnType boolean 
	* @author: 
	* @Created 2012 2012-9-20上午08:37:30 
	*/ 
	public static boolean isEqual(Date firstDate, Date secondDate) { 

	  return compare(firstDate, secondDate) == 0 ? true : false; 
	} 

	/** 
	* 
	* @Description:比较两个时间点 
	* 如果secondDate表示的时间等于此 firstDate 表示的时间，则返回 0 值； 
	* 如果此 firstDate 的时间在参数表示的时间之前，则返回小于 0 的值； 
	* 如果此 firstDate 的时间在参数表示的时间之后，则返回大于 0 的值 
	* @param firstDate 
	* @param secondDate 
	* @ReturnType int 
	* @author: 
	* @Created 2012 2012-9-20上午08:34:33 
	*/ 
	public static int compare(Date firstDate, Date secondDate) { 

	Calendar firstCalendar = null; 
	/**使用给定的 Date 设置此 Calendar 的时间。**/ 
		if (firstDate != null) { 
		firstCalendar = Calendar.getInstance(); 
		firstCalendar.setTime(firstDate); 
	} 

	Calendar secondCalendar = null; 
	/**使用给定的 Date 设置此 Calendar 的时间。**/ 
		if (firstDate != null) { 
		secondCalendar = Calendar.getInstance(); 
		secondCalendar.setTime(secondDate); 
	} 

	try { 
	/** 
	* 比较两个 Calendar 对象表示的时间值（从历元至现在的毫秒偏移量）。 
	* 如果参数表示的时间等于此 Calendar 表示的时间，则返回 0 值； 
	* 如果此 Calendar 的时间在参数表示的时间之前，则返回小于 0 的值； 
	* 如果此 Calendar 的时间在参数表示的时间之后，则返回大于 0 的值 
	* **/ 
	 return firstCalendar.compareTo(secondCalendar); 
	} catch (NullPointerException e) { 
	throw new IllegalArgumentException(e); 
	} catch (IllegalArgumentException e) { 
	throw new IllegalArgumentException(e); 
	} 
	}
	/**
	 * 两个时间相差几个月
	 * @param date1
	 * @param date2
	 * @return
	 * @throws ParseException
	 */
	public static int getMonthSpace(Date start, Date end) {
        if (start.after(end)) {
            Date t = start;
            start = end;
            end = t;
        }
        Calendar startCalendar = Calendar.getInstance();
        startCalendar.setTime(start);
        Calendar endCalendar = Calendar.getInstance();
        endCalendar.setTime(end);
        Calendar temp = Calendar.getInstance();
        temp.setTime(end);
        temp.add(Calendar.DATE, 1);

        int year = endCalendar.get(Calendar.YEAR)
                - startCalendar.get(Calendar.YEAR);
        int month = endCalendar.get(Calendar.MONTH)
                - startCalendar.get(Calendar.MONTH);

        if ((startCalendar.get(Calendar.DATE) == 1)
                && (temp.get(Calendar.DATE) == 1)) {
            return year * 12 + month + 1;
        } else if ((startCalendar.get(Calendar.DATE) != 1)
                && (temp.get(Calendar.DATE) == 1)) {
            return year * 12 + month;
        } else if ((startCalendar.get(Calendar.DATE) == 1)
                && (temp.get(Calendar.DATE) != 1)) {
            return year * 12 + month;
        } else {
            return (year * 12 + month - 1) < 0 ? 0 : (year * 12 + month);
        }
    }
	
	/**
     * 获取当前时间指定前面多少小时的时间 
     * @param ihour
     * @return
     */
    public static String getBeforeHourTime(int hour){  
    	gregorianCalendar = new GregorianCalendar();
    	gregorianCalendar.set(Calendar.HOUR_OF_DAY, gregorianCalendar.get(Calendar.HOUR_OF_DAY) - hour);  
    	return dateFormatter.format(gregorianCalendar.getTime());  
    }  
    
    
    /**
     * 获取当前时间前一周的时间
     * @param ihour
     * @return
     */
    public static String getBeforeWeek(int week){ 
    	gregorianCalendar = new GregorianCalendar();
    	gregorianCalendar.set(Calendar.WEEK_OF_MONTH, gregorianCalendar.get(Calendar.WEEK_OF_MONTH) - week);  
    	return dateFormatter.format(gregorianCalendar.getTime());  
    } 
    
    /**
     * 获取提前多少个月
     * 
     * @param monty
     * @return
     */
    public static String getBeforeMonth(int month) {
    	gregorianCalendar = new GregorianCalendar();
    	gregorianCalendar.set(Calendar.MONTH, gregorianCalendar.get(Calendar.MONTH) - month);  
    	return dateFormatter.format(gregorianCalendar.getTime()); 
    }
    
    /**
     * 获取提前多少个年
     * 
     * @param monty
     * @return
     */
    public static String getBeforeYear(int year) {
    	gregorianCalendar = new GregorianCalendar();
    	gregorianCalendar.set(Calendar.YEAR, gregorianCalendar.get(Calendar.YEAR) - year);  
    	return dateFormatter.format(gregorianCalendar.getTime()); 
    }
    
    
    /**
     * 日期格式字符串转换成时间戳
     *
     * @param dateStr 字符串日期
     * @param format   如：yyyy-MM-dd HH:mm:ss
     *
     * @return
     */
    public static String Date2TimeStamp(String dateStr) {
        try {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            return format(sdf.parse(dateStr));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }
    
    
    /** 
     * 获取过去第几天的日期 
     * 
     * @param past 
     * @return 
     */  
    public static String getPastDate(int past) {  
        Calendar calendar = Calendar.getInstance();  			//获取当前日期
        // Calendar.DAY_OF_YEAR:获取这一天是这一年中的第几天
        calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - past); 
        Date today = calendar.getTime();  
        SimpleDateFormat format = new SimpleDateFormat("MM-dd");  
        String result = format.format(today);  
        return result;  
    } 
    
    
    /**
     * 获取过去7天日期数组
     * @return
     */
    public static String[] getPastDateArr(){
    	String[] dateArr=new String[7];
    	dateArr[0]=formatter4.format(new Date());
    	for (int i = 1; i < 7; i++) {
			String date=getPastDate(i);
			dateArr[i]=date;
		}
    	 Arrays.sort(dateArr);   //从小到大升序排序
    	return dateArr;
    }

}