生成随机出生date
我试图使用Java程序为我的数据库中的人生成随机出生date。 我将如何做到这一点？
import java.util.GregorianCalendar; public class RandomDateOfBirth { public static void main(String[] args) { GregorianCalendar gc = new GregorianCalendar(); int year = randBetween(1900, 2010); gc.set(gc.YEAR, year); int dayOfYear = randBetween(1, gc.getActualMaximum(gc.DAY_OF_YEAR)); gc.set(gc.DAY_OF_YEAR, dayOfYear); System.out.println(gc.get(gc.YEAR) + "-" + (gc.get(gc.MONTH) + 1) + "-" + gc.get(gc.DAY_OF_MONTH)); } public static int randBetween(int start, int end) { return start + (int)Math.round(Math.random() * (end - start)); } } java.util.Date有一个构造函数 ，它接受自Epoch以来的毫秒数，而java.util.Random有一个方法可以给你一个随机的毫秒数。 你会想要根据你想要的DOB的范围来设置一个随机值的范围，但这些应该这样做。
非常大致：
Random rnd; Date dt; long ms; // Get a new random instance, seeded from the clock rnd = new Random(); // Get an Epoch value roughly between 1940 and 2010 // -946771200000L = January 1, 1940 // Add up to 70 years to it (using modulus on the next long) ms = -946771200000L + (Math.abs(rnd.nextLong()) % (70L * 365 * 24 * 60 * 60 * 1000)); // Construct a date dt = new Date(ms);
你需要定义一个随机date，对吧？
一个简单的方法就是生成一个新的Date对象，使用一个long （ 1970年1月1日以来的时间以毫秒为单位 ），然后减去一个随机的long ：
new Date(Math.abs(System.currentTimeMillis() - RandomUtils.nextLong()));
（ RandomUtils取自Apache Commons Lang）。
当然，这远远不是一个真正的随机date（例如，你不会在1970年之前得到date），但是我认为这足以满足你的需求。
否则，您可以使用Calendar类创build自己的date：
int year = // generate a year between 1900 and 2010; int dayOfYear = // generate a number between 1 and 365 (or 366 if you need to handle leap year); Calendar calendar = Calendar.getInstance(); calendar.set(Calendar.YEAR, randomYear); calendar.set(Calendar.DAY_OF_YEAR, dayOfYear); Date randomDoB = calendar.getTime();
针对基于Java 8的解决scheme的代码片段：
Random random = new Random(); int minDay = (int) LocalDate.of(1900, 1, 1).toEpochDay(); int maxDay = (int) LocalDate.of(2015, 1, 1).toEpochDay(); long randomDay = minDay + random.nextInt(maxDay - minDay); LocalDate randomBirthDate = LocalDate.ofEpochDay(randomDay); System.out.println(randomBirthDate);
注意 ：这会在1月1日（含）至1月20日（不含）之间随机生成一个date。
注意 ：它基于时代天数 ，即相对于1月1970日（ EPOCH ）的天数 – EPOCH之后的正面含义，EPOCH之前的负面含义
你也可以创build一个小实用程序类：
public class RandomDate { private final LocalDate minDate; private final LocalDate maxDate; private final Random random; public RandomDate(LocalDate minDate, LocalDate maxDate) { this.minDate = minDate; this.maxDate = maxDate; this.random = new Random(); } public LocalDate nextDate() { int minDay = (int) minDate.toEpochDay(); int maxDay = (int) maxDate.toEpochDay(); long randomDay = minDay + random.nextInt(maxDay - minDay); return LocalDate.ofEpochDay(randomDay); } @Override public String toString() { return "RandomDate{" + "maxDate=" + maxDate + ", minDate=" + minDate + '}'; } }
并像这样使用它：
RandomDate rd = new RandomDate(LocalDate.of(1900, 1, 1), LocalDate.of(2010, 1, 1)); System.out.println(rd.nextDate()); System.out.println(rd.nextDate()); // birthdays ad infinitum
生成随机出生date：
import java.util.Calendar; public class Main { public static void main(String[] args) { for (int i = 0; i < 100; i++) { System.out.println(randomDOB()); } } public static String randomDOB() { int yyyy = random(1900, 2013); int mm = random(1, 12); int dd = 0; // will set it later depending on year and month switch(mm) { case 2: if (isLeapYear(yyyy)) { dd = random(1, 29); } else { dd = random(1, 28); } break; case 1: case 3: case 5: case 7: case 8: case 10: case 12: dd = random(1, 31); break; default: dd = random(1, 30); break; } String year = Integer.toString(yyyy); String month = Integer.toString(mm); String day = Integer.toString(dd); if (mm < 10) { month = "0" + mm; } if (dd < 10) { day = "0" + dd; } return day + '/' + month + '/' + year; } public static int random(int lowerBound, int upperBound) { return (lowerBound + (int) Math.round(Math.random() * (upperBound - lowerBound))); } public static boolean isLeapYear(int year) { Calendar calendar = Calendar.getInstance(); calendar.set(Calendar.YEAR, year); int noOfDays = calendar.getActualMaximum(Calendar.DAY_OF_YEAR); if (noOfDays > 365) { return true; } return false; } }
您可以检出随机数发生器的随机数据。这个库有助于从给定的模型类创build随机数据。下面的示例代码结帐。
public class Person { @DateValue( from = "01 Jan 1990",to = "31 Dec 2002" , customFormat = "dd MMM yyyy") String dateOfBirth; } //Generate random 100 Person(Model Class) object Generator<Person> generator = new Generator<>(Person.class); List<Person> persons = generator.generate(100);
由于有许多内置的数据生成器可以使用注释访问，您也可以构build自定义数据生成器。我build议您浏览库页面上提供的文档。
看这个方法：
public static Date dateRandom(int initialYear, int lastYear) { if (initialYear > lastYear) { int year = lastYear; lastYear = initialYear; initialYear = year; } Calendar cInitialYear = Calendar.getInstance(); cInitialYear.set(Calendar.YEAR, 2015); long offset = cInitialYear.getTimeInMillis(); Calendar cLastYear = Calendar.getInstance(); cLastYear.set(Calendar.YEAR, 2016); long end = cLastYear.getTimeInMillis(); long diff = end - offset + 1; Timestamp timestamp = new Timestamp(offset + (long) (Math.random() * diff)); return new Date(timestamp.getTime()); }
如果你不介意添加一个新的库到你的代码，你可以使用MockNeat （免责声明：我是其中一个作者）。
MockNeat mock = MockNeat.threadLocal(); // Generates a random date between [1970-1-1, NOW) LocalDate localDate = mock.localDates().val(); System.out.println(localDate); // Generates a random date in the past // but beore 1987-1-30 LocalDate min = LocalDate.of(1987, 1, 30); LocalDate past = mock.localDates().past(min).val(); System.out.println(past); LocalDate max = LocalDate.of(2020, 1, 1); LocalDate future = mock.localDates().future(max).val(); System.out.println(future); // Generates a random date between 1989-1-1 and 1993-1-1 LocalDate start = LocalDate.of(1989, 1, 1); LocalDate stop = LocalDate.of(1993, 1, 1); LocalDate between = mock.localDates().between(start, stop).val(); System.out.println(between);
对于Java8 – >假设出生的数据必须在当天之前：
import java.time.LocalDate; import java.time.LocalTime; import java.time.Period; import java.time.temporal.ChronoUnit; import java.util.Random; public class RandomDate { public static LocalDate randomBirthday() { return LocalDate.now().minus(Period.ofDays((new Random().nextInt(365 * 70)))); } public static void main(String[] args) { System.out.println("randomDate: " + randomBirthday()); } }
我认为这将做到这一点：
public static void main(String[] args) { Date now = new Date(); long sixMonthsAgo = (now.getTime() - 15552000000l); long today = now.getTime(); for(int i=0; i<10; i++) { long ms = ThreadLocalRandom.current().nextLong(sixMonthsAgo, today); Date date = new Date(ms); System.out.println(date.toString()); } }
如果您不介意第三方库，那么Utils库有一个RandomDateUtils ，它会生成随机java.util.Dates以及Java 8的date和时间API中的所有date，时间，瞬间和持续时间
LocalDate birthDate = RandomDateUtils.randomPastLocalDate(); LocalDate today = LocalDate.now(); LocalDate under18YearsOld = RandomDateUtils.randomLocalDate(today.minus(18, YEARS), today); LocalDate over18YearsOld = RandomDateUtils.randomLocalDateBefore(today.minus(18, YEARS));
它位于Maven Central Repository中：
<dependency> <groupId>com.github.rkumsher</groupId> <artifactId>utils</artifactId> <version>1.0</version> </dependency>
我正在学习Scala，并最终select在范围之间随机selectdate的Googling Java解决scheme。 我发现这个post超级有用，这是我的最终解决scheme。 希望它可以帮助未来的Scala和Java程序员。
import java.sql.Timestamp def date_rand(ts_start_str:String = "2012-01-01 00:00:00", ts_end_str:String = "2015-01-01 00:00:00"): String = { val ts_start = Timestamp.valueOf(ts_start_str).getTime() val ts_end = Timestamp.valueOf(ts_end_str).getTime() val diff = ts_end - ts_start println(diff) val ts_rand = new Timestamp(ts_start + (Random.nextFloat() * diff).toLong) return ts_rand.toString } //> date_rand: (ts_start_str: String, ts_end_str: String)String println(date_rand()) //> 94694400000 //| 2012-10-28 18:21:13.216 println(date_rand("2001-01-01 00:00:00", "2001-01-01 00:00:00")) //> 0 //| 2001-01-01 00:00:00.0 println(date_rand("2001-01-01 00:00:00", "2010-01-01 00:00:00")) //> 283996800000 //| 2008-02-16 23:15:48.864 //> 2013-12-21 08:32:16.384
你会得到日/月/年
你可以使用Math.random（）函数，就像我在下面做的那样
这里我们产生3个随机数，从1到31,1到12,1990到2016，并在它们之间连接“/”
public static String getRandomJoinDate() { String date=""; int yearBegin=1990; int yearEnd=2016-yearBegin; date=""+(1 + (int)(Math.random() * 31)+"/"+(1 + (int)(Math.random() * 12)+"/"+(yearBegin + (int)(Math.random() * yearEnd)))); return date; }
要了解更多关于Math.random（）链接可能会有所帮助
Math.random（）解释
