Java开发基础日期类代码详解

发布时间：2020-05-23 12:27:43 所属栏目：Java 来源：互联网

导读：由于工作关系，很久没更新博客了，今天就给大家带来一篇Java实现获取指定月份的星期与日期对应关系的文章，好了，不多说，我们直接上代码：

由于工作关系，很久没更新博客了，今天就给大家带来一篇Java实现获取指定月份的星期与日期对应关系的文章，好了，不多说，我们直接上代码：

一、日期工具类

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,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,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);
	}
}

二、测试类

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))); 
  } 
}

三、测试结果

{
  "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"
  ]
}

总结

本文通过代码示例向大家展示了日期工具类的几种用法，希望对大家学习Java有所帮助。

感兴趣的朋友可以参阅：Java语言Lang包下常用的工具类介绍、Java AtomicInteger类的使用方法详解等以及本站其他相关专题，如有不足之处，欢迎留言指出，小编会及时回复大家并更正。感谢朋友们对编程小技巧网站的支持！

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