In real world, we may need some common functions to fulfill our requirement, such as:
1. check date string has expected format
2. convert date string to java.util.Date, and vice versa.
3. validate start and date time
We can use commons-validator to implement this function easily.
Remember to add dependency in your pom.xml
1 2 3 4 5 | <dependency> <groupId>commons-validator</groupId> <artifactId>commons-validator</artifactId> <version>1.6</version> </dependency> |
Sample code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 | package albert.practice.validation; import java.util.Date; import org.apache.commons.validator.routines.DateValidator; public class DateUtils { /** * 檢查 date string 格式是否符合 yyyy/MM/dd 格式. * * @param dateString */ public static void validateDate(String dateString) { if (!DateValidator.getInstance().isValid(dateString, "yyyy/MM/dd")) { throw new IllegalArgumentException("Valid date format is yyyy/MM/dd"); } } /** * 檢查 date string 格式是否符合 yyyy/MM/dd 格式, 若符合則回傳 java.util.Date * * @param dateString * ex. 2017/9/14 * @return java.util.Date */ public static Date convertToDate(String dateString) { validateDate(dateString); return DateValidator.getInstance().validate(dateString, "yyyy/MM/dd"); } /** * 將 Date 轉成指定格式 (ex. yyyy/MM/dd)的 date string. * * @param date * java.util.Date * @param pattern * ex. yyyy/MM/dd * @return date String */ public static String convertToString(Date date, String pattern) { return DateValidator.getInstance().format(date, pattern); } /** * 時間起迄檢查. * * @param startDate * 開始日期 * @param endDate * 結束日期 */ public static void compareDays(Date startDate, Date endDate) { int compare = DateValidator.getInstance().compareDates(startDate, endDate, null); if (compare > 0) { throw new IllegalArgumentException("結束時間不可早於開始時間"); } } } |
Test class:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | package albert.practice.validation; import static org.junit.Assert.assertEquals; import java.util.Date; import org.junit.Before; import org.junit.Test; public class DateUtilsTest { private String validDate = ""; private String invalidDate = ""; private String startDate = ""; private String endDate = ""; private String invalidEndDate = ""; @Before public void setup() { validDate = "2017/09/30"; invalidDate = "2017/09/31"; startDate = "2017/9/14"; endDate = "2017/9/15"; invalidEndDate = "2017/9/11"; } @Test(expected = IllegalArgumentException.class) public void testInvalidDate() { DateUtils.validateDate(invalidDate); } @Test public void testValidDate() { DateUtils.validateDate(validDate); } @Test public void testDateConversion() { Date date = DateUtils.convertToDate(validDate); String dateString = DateUtils.convertToString(date, "yyyy/MM/dd"); assertEquals("2017/09/30", dateString); } @Test public void testValidStartAndEndDate() { DateUtils.compareDays(DateUtils.convertToDate(startDate), DateUtils.convertToDate(endDate)); } @Test(expected = IllegalArgumentException.class) public void testInvalidStartAndEndDate() { DateUtils.compareDays(DateUtils.convertToDate(startDate), DateUtils.convertToDate(invalidEndDate)); } } |
