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"
  ]
}