修复FastDatePrinter处理YY错误问题

CHANGELOG.md

@@ -28,6 +28,7 @@
 * 【core   】      修复Tailer指定初始读取行数的计算错误问题（issue#IA77ML@Gitee）
 * 【http   】      修复getFileNameFromDisposition获取头错误问题（issue#3632@Github）
 * 【core   】      修复\n#出现在双引号中解析错误问题（issue#IA8WE0@Gitee）
+* 【core   】      修复FastDatePrinter处理YY错误问题（issue#3641@Github）
 
 -------------------------------------------------------------------------------------------------------------
 # 5.8.28(2024-05-29)

hutool-core/src/main/java/cn/hutool/core/date/format/FastDatePrinter.java

@@ -23,13 +23,18 @@ import java.util.concurrent.ConcurrentMap;
 public class FastDatePrinter extends AbstractDateBasic implements DatePrinter {
 	private static final long serialVersionUID = -6305750172255764887L;
 
-	/** 规则列表. */
+	/**
+	 * 规则列表.
+	 */
 	private transient Rule[] rules;
-	/** 估算最大长度. */
+	/**
+	 * 估算最大长度.
+	 */
 	private transient int mMaxLengthEstimate;
 
 	// Constructor
 	// -----------------------------------------------------------------------
+
 	/**
 	 * 构造，内部使用<br>
 	 *
@@ -59,6 +64,7 @@ public class FastDatePrinter extends AbstractDateBasic implements DatePrinter {
 
 	// Parse the pattern
 	// -----------------------------------------------------------------------
+
 	/**
 	 * <p>
 	 * Returns a list of Rules given a pattern.
@@ -391,6 +397,7 @@ public class FastDatePrinter extends AbstractDateBasic implements DatePrinter {
 
 	// Serializing
 	// -----------------------------------------------------------------------
+
 	/**
 	 * Create the object after serialization. This implementation reinitializes the transient properties.
 	 *
@@ -490,6 +497,7 @@ public class FastDatePrinter extends AbstractDateBasic implements DatePrinter {
 
 	// Rules
 	// -----------------------------------------------------------------------
+
 	/**
 	 * 规则
 	 */
@@ -691,7 +699,6 @@ public class FastDatePrinter extends AbstractDateBasic implements DatePrinter {
 
 		/**
 		 * Constructs an instance of {@code UnpaddedMonthField}.
-		 *
 		 */
 		UnpaddedMonthField() {
 		}
@@ -1038,7 +1045,12 @@ public class FastDatePrinter extends AbstractDateBasic implements DatePrinter {
 
 		@Override
 		public void appendTo(Appendable buffer, Calendar calendar) throws IOException {
-			mRule.appendTo(buffer, calendar.getWeekYear());
+			int weekYear = calendar.getWeekYear();
+			if (mRule instanceof TwoDigitYearField) {
+				// issue#3641
+				weekYear %= 100;
+			}
+			mRule.appendTo(buffer, weekYear);
 		}
 
 		@Override
@@ -1269,6 +1281,7 @@ public class FastDatePrinter extends AbstractDateBasic implements DatePrinter {
 	}
 
 	// ----------------------------------------------------------------------
+
 	/**
 	 * <p>
 	 * Inner class that acts as a compound key for time zone names.

hutool-core/src/test/java/cn/hutool/core/date/FastDateFormatTest.java

@@ -0,0 +1,58 @@
+package cn.hutool.core.date;
+
+import cn.hutool.core.date.format.FastDateFormat;
+import org.junit.Test;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.TimeZone;
+
+import static org.junit.Assert.assertEquals;
+
+public class FastDateFormatTest {
+	private static final TimeZone timezone = TimeZone.getTimeZone("Etc/Utc");
+
+	private static FastDateFormat getHutoolInstance(String pattern) {
+		return FastDateFormat.getInstance(pattern, timezone);
+	}
+
+	@Test
+	public void yearTest() {
+		Date date = DateUtil.date(0L);
+
+		assertEquals(
+			"1970-01-01 00:00:00",
+			getHutoolInstance("yyyy-MM-dd HH:mm:ss").format(date)
+		);
+
+		assertEquals(
+			"1970-01-01 00:00:00",
+			getHutoolInstance("YYYY-MM-dd HH:mm:ss").format(date)
+		);
+
+		assertEquals(
+			"1970",
+			getHutoolInstance("YYYY").format(date)
+		);
+
+		assertEquals(
+			"70",
+			getHutoolInstance("yy").format(date)
+		);
+	}
+
+	@Test
+	public void weekYearTest() {
+		Date date = DateUtil.date(0L);
+
+		assertEquals(
+			"70",
+			new SimpleDateFormat("YY").format(date)
+		);
+
+		assertEquals(
+			"70",
+			getHutoolInstance("YY").format(date)
+		);
+	}
+}