java的工具类

package com.mintcode.jkys.util;

import hirondelle.date4j.DateTime;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.TimeZone;

public abstract class DateUtil {

public static final String PATTERN_YEAR2MONTH = "yyyyMM";
public static final String PATTERN_YEAR2DAY = "yyyyMMdd";
public static final String PATTERN_YEAR2SECOND = "yyyyMMddHHmmss";
public static final String PATTERN_YEAR2MILLISECOND = "yyyyMMddHHmmssSSS";
public static final String PATTERN_NORMAL_YEAR2SECOND = "yyyy-MM-dd HH:mm:ss";
public static final String PATTERN_NORMAL_YEAR2MILLISECOND = "yyyy-MM-dd HH:mm:ss.SSS";

protected static ThreadLocal<Map<String, DateFormat>> formatLocal = new ThreadLocal<Map<String, DateFormat>>();

public static final int SECONDS_IN_DAY = 60 * 60 * 24;
public static final long MILLIS_IN_DAY = 1000L * SECONDS_IN_DAY;

    public static boolean isSameDayOfMillis(final long ms1, final long ms2) {
        final long interval = ms1 - ms2;
        return interval < MILLIS_IN_DAY
                && interval > -1L * MILLIS_IN_DAY
                && toDay(ms1) == toDay(ms2);
    }

    private static long toDay(long millis) {
        return (millis + TimeZone.getDefault().getOffset(millis)) / MILLIS_IN_DAY;
    }
   
/**
* 获取pattern样式的DateFormat 线程安全
*
* @param pattern
* @return
*/
protected static DateFormat getFormat(String pattern) {
Map<String, DateFormat> formatMap = formatLocal.get();

if (formatMap == null) {
formatMap = new HashMap<String, DateFormat>();
formatLocal.set(formatMap);
}

DateFormat format = formatMap.get(pattern);

if (format == null) {
format = new SimpleDateFormat(pattern);
formatMap.put(pattern, format);
}

return format;
}

/**
* 校验
*
* @param dateStr
* @param pattern
* @return
*/
public static boolean valid(String dateStr, String pattern) {
try {
getFormat(pattern).parse(dateStr);
} catch (ParseException e) {
return false;
}
return true;
}

/**
* 解析日期字符串
*
* @param dateStr
* @param pattern
* @return
*/
public static Date parse(String dateStr, String pattern) {
if (dateStr == null) {
return null;
}
try {
return getFormat(pattern).parse(dateStr);
} catch (ParseException e) {
throw new RuntimeException(e);
}
}

/**
* 格式化
*
* @param date
* @param pattern
* @return
*/
public static String format(Date date, String pattern) {
if (date == null) {
return null;
}
return getFormat(pattern).format(date);
}

/**
* 将时间转换成Long型
*
* @param date
* @return
*/
public static Long parseToLong(Date date, String pattern) {
return Long.valueOf(format(date, pattern));
}

/**
* 获取当前时间
*
* @return
*/
public static Date now() {
return new Date();
}

public static Long nowInMilliseconds() {
return System.currentTimeMillis();
}

public static Integer nowInSeconds() {
return (int) (System.currentTimeMillis() / 1000);
}


/**
* <pre>
* 返回给定日期在当前周里的索引, 1~7对应周一~周日
* </pre>
* @param date
* @return
*/
public static int getWeekDay(Date date) {
DateTime dateTime = DateTime.forInstant(date.getTime(), TimeZone.getDefault());
int i = dateTime.getWeekDay();
i --;
i = i == 0 ? 7 : i;
return i;
}
}