增加1899单元测试

hutool-poi/src/test/java/cn/hutool/poi/excel/NumericCellValueTest.java

@@ -0,0 +1,26 @@
+package cn.hutool.poi.excel;
+
+import cn.hutool.poi.excel.cell.values.NumericCellValue;
+import java.util.Date;
+import org.apache.poi.ss.usermodel.Cell;
+import org.junit.Test;
+
+public class NumericCellValueTest {
+
+	@Test
+	public void writeTest() {
+		final ExcelReader reader = ExcelUtil.getReader("1899bug_demo.xlsx");
+		ExcelWriter writer = ExcelUtil.getWriter("1899bug_write.xlsx");
+		Cell cell = reader.getCell(0, 0);
+		// 直接取值
+		// 和CellUtil.getCellValue(org.apache.poi.ss.usermodel.Cell)方法的结果一样
+		// 1899-12-31 04:39:00
+		Date cellValue = cell.getDateCellValue();
+		// 将这个值写入EXCEL中自定义样式的单元格，结果会是-1
+		writer.writeCellValue(0, 0, cellValue);
+		// 修改后的写入，单元格内容正常
+		writer.writeCellValue(1, 0, new NumericCellValue(cell).getValue());
+		writer.close();
+		reader.close();
+	}
+}