时间工具类

/*
 * Copyright (c) 2009, 2010, 2011, 2012, 2013 tinygao
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package jdk.date;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.apache.commons.lang.StringUtils;

/**
 * @author tingao
 * 2013-1-5
 */
public final class DateUtils {

	private static Logger log = Logger.getLogger(DateUtils.class.getName());
	private static ThreadLocal<DateFormat> timeMap = new ThreadLocal<DateFormat>();
	private static final String dateFormat = "yyyy-MM-dd hh:mm:ss";
	
	/**
	 * 将时间转换成一定格式的日期字符串
	 * 如果dateFromat为空，就按照默认的格式输出
	 * @param date 日期
	 * @param dateFormat 转成字符串日期格式
	 * @return dateFormt格式的日期
	 * 2013-1-5 上午11:04:03
	 */
	public static String formatDate(Date date, String dateFormat) {
		if(StringUtils.isEmpty(dateFormat)) {
			dateFormat = DateUtils.dateFormat;
		}
		String result = "";
		DateFormat dt = instanceDateFormat(dateFormat);
		result = dt.format(date);
		return result;
	}
	
	/**
	 * @param str
	 * @param dateFormat
	 * @return
	 * 2013-1-5 上午11:06:26
	 */
	public static Date parse(String str, String dateFormat) {
		
		if(StringUtils.isEmpty(dateFormat)) {
			dateFormat = DateUtils.dateFormat;
		}
		try {
			DateFormat dt = instanceDateFormat(dateFormat);
			return dt.parse(str);
		} catch (ParseException e) {
			log.log(Level.SEVERE, "从字符串转时间出错，详情："+e.toString());
		}
		return null;
	}
	
	public static Date parse(String str) {
		return parse(str, null);
	}
	
	public static String formatDate(Date date) {
		return formatDate(date, null);
	}
	
	private static DateFormat instanceDateFormat(String dateFormat) {
		DateFormat dt = timeMap.get();
		if(dt == null) {
			dt = new SimpleDateFormat(dateFormat);
			timeMap.set(dt);
		}
		return dt;
	}
	
	
	//test
	/*static class ThreadA implements Runnable {
		int i = 0;
		@Override
		public void run() {
			while(i++ < 100) {
				String date = formatDate(new Date(), "yyyy-MM-dd");
				System.out.println("线程A"+i+"：" + date);
			}
		}
	}
	
	static class ThreadB implements Runnable {
		int i = 0;
		@Override
		public void run() {
			while(i++ < 100) {
				String date = formatDate(new Date(), "yyyy-MM-dd hh:mm");
				System.out.println("线程B"+i+"：" + date);
			}
		}
	}
	
	public static void main(String[] args) {
		String str = formatDate(new Date());
		System.out.println(str);
		
		Date date = parse("2013-01-05 11:11:16");
		System.out.println(date);
		
		ThreadA threadA = new ThreadA();
		Thread tha = new Thread(threadA);
		tha.start();
		
		ThreadB threadB = new ThreadB();
		Thread thb = new Thread(threadB);
		thb.start();
		
	}*/
}