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package com.jplus.core.plugin.scheduling.cron;import java.util.Arrays;import java.util.Calendar;import java.util.Date;import java.util.List;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;import com.jplus.core.utill.Assert;import com.jplus.core.utill.JUtil;/** * Cron 表达式解析与时间获取 * ** CronKit cron = new CronKit("0 0 1 1 * ? *"); * Date next = cron.next(); ** * * @author Yuanqy https://my.oschina.net/jweb/blog/786444 */public class CronKit { private final String cron; private final Long[] crop;// 范围 private Lock lock = new ReentrantLock(); // 辅助Calendar线程安全 private final Calendar cal = Calendar.getInstance();// 实例化是线程安全的，但多个线程对同一Cal操作时是非线程安全的 /** * 支持6-7位长度cron表达式 * 不支持字符：L W C # * @param cron */ public CronKit(String cron) { Assert.notNull(cron, "error: cron must be not null"); cron = cron.replaceAll("\\s+", " ").trim(); this.cron = cron; this.crop = parse(cron); } public String getCron() { return cron; } public Long getCrop(int i) { return crop[i]; } private Long getP(Bounds bound) { return crop[bound.index]; } // Java(Spring) // * * * * * * * // - - - - - - - 秒 分 时 天 月 周 年 // | | | | | | +--- year [optional(1970-2099)] // | | | | | +----- day of week (1 - 7) (Sunday=7) L C # // | | | | +------- month (1 - 12) // | | | +--------- day of month (1 - 31) L W C // | | +----------- hour (0 - 23) // | +------------- min (0 - 59) // +--------------- second (0 - 59) private enum Bounds { seconds (0, 0, 59, Calendar.SECOND), minutes (1, 0, 59, Calendar.MINUTE), hours (2, 0, 23, Calendar.HOUR_OF_DAY), dom (3, 1, 31, Calendar.DAY_OF_MONTH), // Day1 months (4, 1, 12, Calendar.MONTH), // Calendar.MONTH的范围是0-11 dow (5, 1, 7, Calendar.DAY_OF_WEEK), // Day2 year (6, 1970, 9999, Calendar.YEAR); public int index; public int min; public int max; public int calType; private Bounds(int index, int min, int max, int calType) { this.index = index; this.min = min; this.max = max; this.calType = calType; } public static Bounds getIndex(int index) { for (Bounds en : Bounds.values()) if (en.index == index) return en; return null; } } private Listmonths = Arrays.asList(new String[]{"JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"}); private List dow = Arrays.asList(new String[]{"SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"}); private Date lastTmp = new Date();// next缓存最后一次时间 // == parse 解析 private Long[] parse(String cron) { String[] items = cron.split(" "); Assert.isTrue(items.length == 6 || items.length == 7, "error： cron length must be 6 or 7 "); Long[] cronPosition = new Long[7]; cronPosition[6] = ~0L; // 默认为年填充所有 for (int i = 0; i < items.length; i++) cronPosition[i] = getField(items[i], i); return cronPosition; } /** * 获取区间范围 */ private long getField(String field, int index) { long bits = 0; if (field.contains(",")) {// 判断一个节点多个条件,递归 String[] items = field.split(","); for (String chars : items) bits |= getField(chars, index); } else { int start = 0, end = 0, step = 1; Bounds bound = Bounds.getIndex(index); if (field.equals("*") || field.equals("?")) { // 是否仅有一个字符是 * 或者 ?。 start = bound.min; end = bound.max; } else if (field.indexOf("-") > 0) {// 是否可以"-"分解为俩数字 String[] items = field.split("-"); start = parseIntOrName(items[0], bound); end = parseIntOrName(items[1], bound); } else if (field.indexOf("/") > 0) {// 是否可以"/"分解为俩数字 String[] items = field.split("/"); end = bound.max; start = bound.min; if (!items[0].equals("*")) start = parseIntOrName(items[0], bound); step = parseIntOrName(items[1], bound); } else {// 默认 单个 start = parseIntOrName(field, bound); end = start; } Assert.isTrue(start >= bound.min, String.format("Start of range (%d) must above the minimum (%d):%s", start, bound.min, field)); Assert.isTrue(end <= bound.max, String.format("End of range (%d) must below the maximum (%d):%s", end, bound.max, field)); Assert.isTrue(start <= end, String.format("Start of range (%d) must below the end of range (%d):%s", start, end, field)); bits |= getBits(start % 100, end % 100, step);// %100主要为了解决year的问题 } return bits; } /** * [核心1]获取区间 * 原理： long类型二进制64位，cron * 表达式所有的范围在0~59之间(除去第七位外)，这样可以把每个可用的点映射到二进制相应的位上。1代表有权限 */ private Long getBits(int start, int end, int step) { Long bits = 0L; if (step == 1) // 当step=1时，可以直接反位并异或获取范围值。 这个if其实可以不要，都用下方的for循环匹配也可以 return ~(Long.MAX_VALUE << (end + 1)) & (Long.MAX_VALUE << start); for (int i = start; i <= end; i += step) bits |= 1L << i; return bits; } private int parseIntOrName(String field, Bounds bound) { if (JUtil.isNumber(field)) return Integer.parseInt(field); else { field = field.toUpperCase(); if (bound == Bounds.months) return months.indexOf(field) + 1; else if (bound == Bounds.dow) return dow.indexOf(field) + 1; else throw new RuntimeException("parseIntOrName No match found:" + field + "[" + bound.index + "]"); } } /** * 获取下一次的执行时间 */ public Date next() { lastTmp = next(lastTmp); return lastTmp; } public Date next(Date date) { lock.lock();// 保证线程安全 try { boolean refresh = true; cal.setTime(date); cal.set(Calendar.MILLISECOND, 0);// 毫秒清零 cal.add(Calendar.SECOND, 1);// +1秒 while (refresh) { boolean again = false; for (int i = 0; i < crop.length; i++) // 自小而大 again |= checkField(cal, Bounds.getIndex(i)); refresh = again; } return cal.getTime(); } catch (Exception e) { throw new RuntimeException(e); } finally { lock.unlock(); } } /** * [核心2]匹配时间 原理：通过位移后(位移方式和getBits方法一致) 判断 二进制范围内是否有匹配上的权限。 */ private boolean checkField(Calendar cal, Bounds bound) { while (((1L << (calGet(cal, bound) % 100)) & getP(bound)) == 0) {// &运算，当匹配上即不为0； cal.add(bound.calType, 1); if (calGet(cal, bound) == bound.min) { clearChild(cal, bound);// 子集清零，当父级轮回，子集也得轮回 return true;// 已轮回，需要重新计算 } } return false;// 表示匹配完成 } private int calGet(Calendar cal, Bounds bound) { int val = cal.get(bound.calType); if (bound == Bounds.months) val += 1;// 如果是months得+1 return val; } private void clearChild(Calendar cal, Bounds bound) { if (bound == Bounds.dow)// dow与dom 只要清空秒,分,时就行了，并不想清空月份 bound = Bounds.dom; for (int i = bound.index - 1; i >= 0; i--) { // 自大而小 Bounds tmp = Bounds.getIndex(i); cal.set(tmp.calType, tmp.min); } }}
测试内容：
private final static SimpleDateFormat SDF = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); @org.junit.Test public void test_Cron() { System.err.println(SDF.format(new Date())); // CronKit cron = new CronKit("1,5 */23 3-5 2/3 * ? *"); // CronKit cron = new CronKit("0 0 1 1 * ? *"); CronKit cron = new CronKit("0/10 1 1 * * THU-SAT *"); System.out.println(JUtil.leftPad(Long.toBinaryString(cron.getCrop(0)), 64, "0") + ":秒 "); System.out.println(JUtil.leftPad(Long.toBinaryString(cron.getCrop(1)), 64, "0") + ":分 "); System.out.println(JUtil.leftPad(Long.toBinaryString(cron.getCrop(2)), 64, "0") + ":时 "); System.out.println(JUtil.leftPad(Long.toBinaryString(cron.getCrop(3)), 64, "0") + ":天 "); System.out.println(JUtil.leftPad(Long.toBinaryString(cron.getCrop(4)), 64, "0") + ":月 "); System.out.println(JUtil.leftPad(Long.toBinaryString(cron.getCrop(5)), 64, "0") + ":周 "); System.out.println(JUtil.leftPad(Long.toBinaryString(cron.getCrop(6)), 64, "0") + ":年 "); for (int i = 0; i < 20; i++) { System.out.println(SDF.format(cron.next())); } } 测试结果：
2019-04-03 14:56:380000000000000100000000010000000001000000000100000000010000000001:秒 0000000000000000000000000000000000000000000000000000000000000010:分 0000000000000000000000000000000000000000000000000000000000000010:时 0000000000000000000000000000000011111111111111111111111111111110:天 0000000000000000000000000000000000000000000000000001111111111110:月 0000000000000000000000000000000000000000000000000000000011100000:周 0000000000000000000000000000111111111111111110000000000000000000:年 2019-04-04 01:01:402019-04-04 01:01:502019-04-05 01:01:002019-04-05 01:01:102019-04-05 01:01:202019-04-05 01:01:302019-04-05 01:01:402019-04-05 01:01:502019-04-06 01:01:002019-04-06 01:01:102019-04-06 01:01:202019-04-06 01:01:302019-04-06 01:01:402019-04-06 01:01:502019-04-11 01:01:002019-04-11 01:01:102019-04-11 01:01:202019-04-11 01:01:302019-04-11 01:01:402019-04-11 01:01:50