Java 日期操作

来源：互联网发布：昆仑虚手游进阶数据编辑：程序博客网时间：2024/05/20 03:08
好久不写代码了，今天写点代码发现日期操作不会了，于是总结了下，在这里记下
package com.wjj.util;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;/** * 日期相关的操作 * @author Dawei *   */public class DateUtil {/** * 将一个字符串转换成日期格式 * @param date * @param pattern * @return */public static Date toDate(String date, String pattern) {if((""+date).equals("")){return null;}if(pattern == null){pattern = "yyyy-MM-dd";}SimpleDateFormat sdf = new SimpleDateFormat(pattern);Date newDate = new Date();try {newDate = sdf.parse(date);} catch (Exception ex) {ex.printStackTrace();}return newDate;}/** * 把日期转换成字符串型 * @param date * @param pattern * @return */public static String toString(Date date, String pattern){if(date == null){return "";}if(pattern == null){pattern = "yyyy-MM-dd";}String dateString = "";SimpleDateFormat sdf = new SimpleDateFormat(pattern);try {dateString = sdf.format(date);} catch (Exception ex) {ex.printStackTrace();}return dateString;}/** * 获取上个月的开始结束时间 * @return */public static String[] getLastMonth() {   // 取得系统当前时间   Calendar cal = Calendar.getInstance();   int year = cal.get(Calendar.YEAR);   int month = cal.get(Calendar.MONTH) + 1;      // 取得系统当前时间所在月第一天时间对象   cal.set(Calendar.DAY_OF_MONTH, 1);      // 日期减一,取得上月最后一天时间对象   cal.add(Calendar.DAY_OF_MONTH, -1);      // 输出上月最后一天日期   int day = cal.get(Calendar.DAY_OF_MONTH);   String months = "";   String days = "";   if (month > 1) {    month--;   } else {    year--;    month = 12;   }   if (!(String.valueOf(month).length() > 1)) {    months = "0" + month;   } else {    months = String.valueOf(month);   }   if (!(String.valueOf(day).length() > 1)) {    days = "0" + day;   } else {    days = String.valueOf(day);   }   String firstDay = "" + year + "-" + months + "-01";   String lastDay = "" + year + "-" + months + "-" + days;   String[] lastMonth = new String[2];   lastMonth[0] = firstDay;   lastMonth[1] = lastDay; //  System.out.println(lastMonth[0] + "||" + lastMonth[1]);   return lastMonth;}/** * 获取当月的开始结束时间 * @return */public static String[] getCurrentMonth() {   // 取得系统当前时间   Calendar cal = Calendar.getInstance();   int year = cal.get(Calendar.YEAR);   int month = cal.get(Calendar.MONTH)+1 ;      // 取得系统当前时间所在月第一天时间对象   cal.set(Calendar.DAY_OF_MONTH, 1);      // 日期减一,取得上月最后一天时间对象   cal.add(Calendar.DAY_OF_MONTH, -1);      // 输出上月最后一天日期   int day = cal.get(Calendar.DAY_OF_MONTH);   String months = "";   String days = "";   if (!(String.valueOf(month).length() > 1)) {    months = "0" + month;   } else {    months = String.valueOf(month);   }   if (!(String.valueOf(day).length() > 1)) {    days = "0" + day;   } else {    days = String.valueOf(day);   }   String firstDay = "" + year + "-" + months + "-01";   String lastDay = "" + year + "-" + months + "-" + days;   String[] currentMonth = new String[2];   currentMonth[0] = firstDay;   currentMonth[1] = lastDay; //  System.out.println(lastMonth[0] + "||" + lastMonth[1]);   return currentMonth;}public static int getDateline(){return (int)(System.currentTimeMillis()/1000);}public static int getDateline(String date){return (int)(toDate(date, "yyyy-MM-dd").getTime()/1000);}}
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