DateUtils.java

package com.lst.lc.utils;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

import org.junit.Test;

public class DateUtils {

        public static String getDateString(Date date) {
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                return sdf.format(date);
        }

        /**
         * 获取年月日字符串
         * 
         * @return
         */
        public static String getDateNum() {
                Calendar c = Calendar.getInstance();
                String year = Integer.toString(c.get(Calendar.YEAR));
                String month = Integer.toString(c.get(Calendar.MONTH));
                String date = Integer.toString(c.get(Calendar.DATE));
                return year + month + date;
        }

        /**
         * 获取年月日时分秒字符串
         * 
         * @return
         */
        public static String getSecNum() {
                Calendar c = Calendar.getInstance();
                String year = Integer.toString(c.get(Calendar.YEAR));
                String month = Integer.toString(c.get(Calendar.MONTH));
                String date = Integer.toString(c.get(Calendar.DATE));
                String hour = Integer.toString(c.get(Calendar.HOUR));
                String minute = Integer.toString(c.get(Calendar.MINUTE));
                String second = Integer.toString(c.get(Calendar.SECOND));
                return year + month + date + hour + minute + second;
        }

        /**
         * 将时间按照格式进行转换
         * 
         * @param date
         *                时间
         * @param format
         *                时间格式
         * @return
         */
        public static String formatDate(Date date, String format) {
                String result = "";
                SimpleDateFormat sdf = new SimpleDateFormat(format);
                if (date != null) {
                        result = sdf.format(date);
                }
                return result;
        }

        /**
         * 将String时间转换成某时间格式
         * 
         * @param str
         *                时间
         * @param format
         *                格式
         * @return
         * @throws Exception
         */
        public static Date formatString(String str, String format)
                        throws Exception {
                if ((str == null) || (str.equals(""))) {
                        return null;
                }
                SimpleDateFormat sdf = new SimpleDateFormat(format);
                return sdf.parse(str);
        }

        /**
         * 获取当前日期时间，24小时制
         * 
         * @return String类型的时间
         * @throws Exception
         */
        public static String getCurrentDateStr() {
                Date date = new Date();
                SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
                return sdf.format(date);
        }

        public static String getCurrentDate() {
                Date date = new Date();
                SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
                return sdf.format(date);
        }
        
        public static String getCurrentDateForShow() {
                Date date = new Date();
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
                return sdf.format(date);
        }

        public static String getCurrentDateMS() {
                Date date = new Date();
                SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS");
                return sdf.format(date);
        }

        /**
         * 获取当前时间的前一天
         * 
         * @return
         */
        public static String getPereviousDayMS() {
                Date date = new Date();
                Calendar calendar = Calendar.getInstance();
                calendar.setTime(date);
                calendar.add(Calendar.DAY_OF_MONTH, -1);
                date = calendar.getTime();
                SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS");
                return sdf.format(date);
        }

        /**
         * 获取距离今日的时间统计
         */
        public static String getLastTime(String lastTime) {
                Long lastTimeL = Long.parseLong(lastTime);
                Long nowTime = new Date().getTime();
                Long range = nowTime - lastTimeL;
                int days = (int) (range / 3600 / 1000 / 24);
                if (days < 1) {
                        SimpleDateFormat sdf = new SimpleDateFormat(
                                        "yyyy-MM-dd HH:mm:ss");
                        String date = sdf.format(new Date(lastTimeL));
                        return date;
                } else if (days < 30) {
                        return days + "天前";
                } else {
                        return "很久以前";
                }
        }

        public static String getStrTime(String strTime) {
                String year = strTime.substring(0, 4);
                String month = strTime.substring(4, 6);
                String day = strTime.substring(6, 8);
                String hour = strTime.substring(8, 10);
                String minute = strTime.substring(10, 12);
                String second = strTime.substring(12, 14);
                return year + "-" + month + "-" + day + " " + hour + ":"
                                + minute + ":" + second;
        }

        public static Date getDateBefore(Date d, int day) {
                Calendar now = Calendar.getInstance();
                now.setTime(d);
                now.set(Calendar.DATE, now.get(Calendar.DATE) - day);
                return now.getTime();
        }
        
        public static String get30Before(){
                Date date = getDateBefore(new Date(), 30);
                SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
                return sdf.format(date);
        }
        
        public static String getBefore(int day){
                Date date = getDateBefore(new Date(), day);
                SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
                return sdf.format(date);
        }
        
        public static String getBeforeForShow(int day){
                Date date = getDateBefore(new Date(), day);
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
                return sdf.format(date);
        }
        
        @Test
        public void test(){
                System.out.println(getCurrentDate());
                System.out.println(get30Before());
        }
        
}