Java开发基础日期类代码详解

java;">package com.lyz.date;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Calendar;import java.util.Date;import java.util.HashMap;import java.util.List;import java.util.Map;import com.chwl.medical.utils.common.CollectionUtils;import com.chwl.medical.utils.common.ObjectUtils;/** * 日期工具类，获取指定月份的星期与日期的对应关系 * @author liuyazhuang * */public class DateUtils {	public static final String DATE_FORMAT = "yyyy-MM-dd";	public enum Type{		Year, Month, Date	}	/**	 * 获取两个时间之间的年份	 * @param startDate	 * @param endDate	 * @return	 */	public static int getYears(Date startDate, Date endDate, Type type){		int count = 0;		 Calendar calBegin = Calendar.getInstance(); //获取日历实例 		 Calendar calEnd = Calendar.getInstance(); 		 calBegin.setTime(startDate);		 calEnd.setTime(endDate);		 if(Type.Year == type){			 count = calEnd.get(Calendar.YEAR) - calBegin.get(Calendar.YEAR); 		 }else if(Type.Month == type){			 count = calEnd.get(Calendar.MONTH) - calBegin.get(Calendar.MONTH); 		 }else{			 count = calEnd.get(Calendar.DATE) - calBegin.get(Calendar.DATE); 		 }		 return count;	}	/**	 * 获取指定月份的所有日期和星期集合	 * @param offset:起止月份, 0：当前月, 1:下一个月; 2下下月； 以此类推... -1:上一个月; -2:上上一个月 ; 以此类推....	 * @param length:终止月份, 0：当前月, 1:下一个月; 2下下月； 以此类推... -1:上一个月; -2:上上一个月 ; 以此类推....	 * @return:日期和星期集合:星期为key 日期为value	 */	public static Map<String, List<String>> getKeyFromMapByValue(int offset, int length){		return getKeyFromMapByValue(getDateKeyWeekValue(offset, length));	}	/**	 * 将以date为key, week为value的map转化为以week为key, date为value的map	 * @param dateWeek	 * @return	 */	public static Map<String, List<String>> getKeyFromMapByValue(Map<String, String> dateWeek){		Map<String, List<String>> weekDate = new HashMap<String, List<String>>();		if(!CollectionUtils.isEmpty(dateWeek)){			for(Map.Entry<String, String> entry : dateWeek.entrySet()){				//获取日期集合				List<String> list = weekDate.get(entry.getValue());				if(ObjectUtils.isEmpty(list)){					list = new ArrayList<String>();				}				list.add(entry.getKey());				weekDate.put(entry.getValue(), list);			}		}		return weekDate;	}	/**	 * 获取指定月份的所有日期和星期集合	 * @param offset:起止月份, 0：当前月, 1:下一个月; 2下下月； 以此类推... -1:上一个月; -2:上上一个月 ; 以此类推....	 * @param length:终止月份, 0：当前月, 1:下一个月; 2下下月； 以此类推... -1:上一个月; -2:上上一个月 ; 以此类推....	 * @return:日期和星期集合:日期为key 星期为value	 */	public static Map<String, String> getDateKeyWeekValue(int offset, int length){		Map<String, String> map = new HashMap<String, String>();		for(int i = offset; i <= length; i++){			List<Date> list = getAllTheDateOftheMonth(new Date(),i);			for(Date date: list){				String weekDay = getDateOfWeek(date);				map.put(parseDateToString(date, DATE_FORMAT), weekDay);			}		}		return map;	}	/**	 * 获取当前日期所在月份的所有日期，指定月份的所有日期	 * @param date:当前日期	 * @param n:1下一月;2:下下月..以此类推; -1:上月,-2:上上月...以此类推	 * @return:返回指定月份的所有日期	 */	public static List<Date> getAllTheDateOftheMonth(Date date, int n) {		List<Date> list = new ArrayList<Date>();		Calendar cal = Calendar.getInstance();		cal.setTime(date);		cal.set(Calendar.DATE, 1);		cal.add(Calendar.MONTH, n);		int month = cal.get(Calendar.MONTH);		while(cal.get(Calendar.MONTH) == month){			list.add(cal.getTime());			cal.add(Calendar.DATE, 1);		}		return list;	}	/**	 * 根据日期获得星期	 * @param date	 * @return	 */	public static String getDateOfWeek(Date date) {		//String[] weekDaysName = { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" };		String[] weekDaysCode = { "0", "1", "2", "3", "4", "5", "6" };		Calendar calendar = Calendar.getInstance();		calendar.setTime(date);		int intWeek = calendar.get(Calendar.DAY_OF_WEEK) - 1;		if(intWeek < 0) intWeek = 0;		return weekDaysCode[intWeek];	}	public static String parseDateToString(Date date, String formatString) {		return getSimpleDateFormat(formatString).format(date);	}	public static SimpleDateFormat getSimpleDateFormat(String formatString) {		return new SimpleDateFormat(formatString);	}}

package com.lyz.date; import net.sf.json.JSONObject; /**  * 测试工具类  * @author liuyazhuang  *  */ public class TestDate {   public static void main(String[] args) {     System.out.println(JSONObject.fromObject(DateUtils.getDateKeyWeekValue(-1, 1)));     System.out.println(JSONObject.fromObject(DateUtils.getKeyFromMapByValue(-1,1)));   } } 

{  "2017-02-28": "2",  "2017-04-19": "3",  "2017-04-17": "1",  "2017-02-25": "6",  "2017-04-18": "2",  "2017-02-24": "5",  "2017-04-15": "6",  "2017-02-27": "1",  "2017-04-16": "0",  "2017-02-26": "0",  "2017-04-13": "4",  "2017-02-21": "2",  "2017-04-14": "5",  "2017-02-20": "1",  "2017-04-11": "2",  "2017-02-23": "4",  "2017-04-12": "3",  "2017-02-22": "3",  "2017-04-21": "5",  "2017-04-20": "4",  "2017-04-08": "6",  "2017-04-09": "0",  "2017-04-04": "2",  "2017-04-05": "3",  "2017-04-06": "4",  "2017-04-07": "5",  "2017-04-01": "6",  "2017-04-02": "0",  "2017-04-03": "1",  "2017-04-10": "1",  "2017-02-07": "2",  "2017-02-06": "1",  "2017-02-09": "4",  "2017-02-08": "3",  "2017-03-29": "3",  "2017-03-25": "6",  "2017-03-26": "0",  "2017-03-27": "1",  "2017-02-01": "3",  "2017-03-28": "2",  "2017-03-21": "2",  "2017-02-03": "5",  "2017-03-22": "3",  "2017-02-02": "4",  "2017-03-23": "4",  "2017-02-05": "0",  "2017-03-24": "5",  "2017-02-04": "6",  "2017-03-31": "5",  "2017-03-30": "4",  "2017-04-23": "0",  "2017-04-22": "6",  "2017-02-19": "0",  "2017-04-25": "2",  "2017-02-18": "6",  "2017-04-24": "1",  "2017-02-17": "5",  "2017-04-27": "4",  "2017-04-26": "3",  "2017-04-29": "6",  "2017-03-18": "6",  "2017-04-28": "5",  "2017-03-19": "0",  "2017-02-12": "0",  "2017-03-16": "4",  "2017-02-11": "6",  "2017-03-17": "5",  "2017-02-10": "5",  "2017-03-14": "2",  "2017-03-15": "3",  "2017-02-16": "4",  "2017-03-12": "0",  "2017-02-15": "3",  "2017-03-13": "1",  "2017-02-14": "2",  "2017-03-10": "5",  "2017-02-13": "1",  "2017-03-11": "6",  "2017-03-20": "1",  "2017-03-09": "4",  "2017-03-08": "3",  "2017-03-07": "2",  "2017-03-06": "1",  "2017-03-05": "0",  "2017-03-04": "6",  "2017-03-03": "5",  "2017-03-02": "4",  "2017-04-30": "0",  "2017-03-01": "3"}

{  "3": [    "2017-04-19",    "2017-04-12",    "2017-02-22",    "2017-04-05",    "2017-02-08",    "2017-03-29",    "2017-02-01",    "2017-03-22",    "2017-04-26",    "2017-03-15",    "2017-02-15",    "2017-03-08",    "2017-03-01"  ],  "2": [    "2017-02-28",    "2017-04-18",    "2017-02-21",    "2017-04-11",    "2017-04-04",    "2017-02-07",    "2017-03-28",    "2017-03-21",    "2017-04-25",    "2017-03-14",    "2017-02-14",    "2017-03-07"  ],  "1": [    "2017-04-17",    "2017-02-27",    "2017-02-20",    "2017-04-03",    "2017-04-10",    "2017-02-06",    "2017-03-27",    "2017-04-24",    "2017-03-13",    "2017-02-13",    "2017-03-20",    "2017-03-06"  ],  "0": [    "2017-04-16",    "2017-02-26",    "2017-04-09",    "2017-04-02",    "2017-03-26",    "2017-02-05",    "2017-04-23",    "2017-02-19",    "2017-03-19",    "2017-02-12",    "2017-03-12",    "2017-03-05",    "2017-04-30"  ],  "6": [    "2017-02-25",    "2017-04-15",    "2017-04-08",    "2017-04-01",    "2017-03-25",    "2017-02-04",    "2017-04-22",    "2017-02-18",    "2017-04-29",    "2017-03-18",    "2017-02-11",    "2017-03-11",    "2017-03-04"  ],  "5": [    "2017-02-24",    "2017-04-14",    "2017-04-21",    "2017-04-07",    "2017-02-03",    "2017-03-24",    "2017-03-31",    "2017-02-17",    "2017-04-28",    "2017-03-17",    "2017-02-10",    "2017-03-10",    "2017-03-03"  ],  "4": [    "2017-04-13",    "2017-02-23",    "2017-04-20",    "2017-04-06",    "2017-02-09",    "2017-02-02",    "2017-03-23",    "2017-03-30",    "2017-04-27",    "2017-03-16",    "2017-02-16",    "2017-03-09",    "2017-03-02"  ]}