Improve IsoFormattingDateDataFormatter

Prior to this commit all date related fields were formatted as an
ISO_LOCAL_DATE_TIME.

With this commit we inspect the type it actually is date, time or
datetime and use the proper ISO_LOCAL formatting for that.

Another improvement is to use the cached result for the formula instead
of re-evaluating the formula and use that type.

spring-batch-excel/src/main/java/org/springframework/batch/extensions/excel/IsoFormattingDateDataFormatter.java

@@ -25,14 +25,13 @@
 import org.apache.poi.ss.usermodel.CellType;
 import org.apache.poi.ss.usermodel.DataFormatter;
 import org.apache.poi.ss.usermodel.DateUtil;
+import org.apache.poi.ss.usermodel.ExcelNumberFormat;
 import org.apache.poi.ss.usermodel.FormulaEvaluator;
 
 /**
  * Specialized subclass for formatting the date into an ISO date/time and ignore the format as given in the Excel file.
  *
  * @author Marten Deinum
- *
- * @see DateTimeFormatter#ISO_OFFSET_DATE_TIME
  */
 public class IsoFormattingDateDataFormatter extends DataFormatter {
 
@@ -46,9 +45,10 @@ public IsoFormattingDateDataFormatter(Locale locale) {
 
 	@Override
 	public String formatRawCellContents(double value, int formatIndex, String formatString, boolean use1904Windowing) {
+
 		if (DateUtil.isADateFormat(formatIndex, formatString) && DateUtil.isValidExcelDate(value)) {
-			return super.formatRawCellContents(value, formatIndex, "yyyy-MM-ddTHH:mm:ss",
-					use1904Windowing);
+			String formatToUse = determineFormat(formatIndex);
+			return super.formatRawCellContents(value, formatIndex, formatToUse, use1904Windowing);
 		}
 		return super.formatRawCellContents(value, formatIndex, formatString, use1904Windowing);
 	}
@@ -60,17 +60,34 @@ public String formatCellValue(Cell cell, FormulaEvaluator evaluator, Conditional
 		}
 
 		CellType cellType = cell.getCellType();
-		if (cellType == CellType.FORMULA) {
-			if (evaluator == null) {
-				return cell.getCellFormula();
-			}
-			cellType = evaluator.evaluateFormulaCell(cell);
+		if (cellType == CellType.FORMULA && useCachedValuesForFormulaCells()) {
+			cellType = cell.getCachedFormulaResultType();
 		}
 
-		if (cellType == CellType.NUMERIC && DateUtil.isCellDateFormatted(cell, cfEvaluator)) {
+		if (cellType != CellType.STRING && DateUtil.isCellDateFormatted(cell, cfEvaluator)) {
+			String formatToUse = determineFormat(ExcelNumberFormat.from(cell, cfEvaluator).getIdx());
 			LocalDateTime value = cell.getLocalDateTimeCellValue();
-			return (value != null) ? value.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) : "";
+			return (value != null) ? value.format(DateTimeFormatter.ofPattern(formatToUse)) : "";
 		}
 		return super.formatCellValue(cell, evaluator, cfEvaluator);
 	}
+
+	/**
+	 * Determine the format to use for either date, time of datetime. Based on the internal formats used by Excel.
+	 * 14, 15, 16, 17 are dates only
+	 * 18, 19, 20, 21 are times only
+	 * anything else is interpreted as a datetime, including custom formats that might be in use!
+	 * @param formatIndex the format index from excel.
+	 * @return the format to use, never {@code null}.
+	 */
+
+	private String determineFormat(int formatIndex) {
+		if (formatIndex >= 14 && formatIndex < 18) {
+			return "yyyy-MM-dd";
+		}
+		else if (formatIndex >= 18 && formatIndex < 22) {
+			return "HH:mm:ss";
+		}
+		return "yyyy-MM-dd'T'HH:mm:ss";
+	}
 }

spring-batch-excel/src/test/java/org/springframework/batch/extensions/excel/poi/PoiItemReaderTypesTests.java → spring-batch-excel/src/test/java/org/springframework/batch/extensions/excel/poi/PoiItemReaderXlsTypesTests.java

@@ -27,7 +27,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 
-class PoiItemReaderTypesTests {
+class PoiItemReaderXlsTypesTests {
 
 	@Test
 	void shouldBeAbleToReadMultipleTypes() throws Exception {
@@ -38,7 +38,6 @@ void shouldBeAbleToReadMultipleTypes() throws Exception {
 		reader.setUserLocale(Locale.US); // Use a Locale to not be dependent on environment
 		reader.afterPropertiesSet();
 
-
 		reader.open(new ExecutionContext());
 
 		var row1 = reader.read();
@@ -62,8 +61,7 @@ void shouldBeAbleToReadMultipleTypesWithDatesAsIso() throws Exception {
 
 		var row1 = reader.read();
 		var row2 = reader.read();
-		assertThat(row1).containsExactly("1", "1.0", "2024-05-12T00:00:00", "1899-12-31T13:14:55", "2024-05-12T13:14:55", "hello world");
-		assertThat(row2).containsExactly("2", "2.5", "2023-08-08T00:00:00", "1899-12-31T11:12:13", "2023-08-08T11:12:13", "world hello");
-
+		assertThat(row1).containsExactly("1", "1.0", "2024-05-12", "13:14:55", "2024-05-12T13:14:55", "hello world");
+		assertThat(row2).containsExactly("2", "2.5", "2023-08-08", "11:12:13", "2023-08-08T11:12:13", "world hello");
 	}
 }

spring-batch-excel/src/test/java/org/springframework/batch/extensions/excel/poi/PoiItemReaderXlsxTypesTests.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2002-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.batch.extensions.excel.poi;
+
+import java.util.Locale;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.batch.extensions.excel.mapping.PassThroughRowMapper;
+import org.springframework.batch.item.ExecutionContext;
+import org.springframework.core.io.ClassPathResource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class PoiItemReaderXlsxTypesTests {
+
+	@Test
+	void shouldBeAbleToReadMultipleTypes() throws Exception {
+		var reader = new PoiItemReader<String[]>();
+		reader.setResource(new ClassPathResource("types.xlsx"));
+		reader.setRowMapper(new PassThroughRowMapper());
+		reader.setLinesToSkip(1); // Skip header
+		reader.setUserLocale(Locale.US); // Use a Locale to not be dependent on environment
+		reader.afterPropertiesSet();
+
+		reader.open(new ExecutionContext());
+
+		var row1 = reader.read();
+		var row2 = reader.read();
+		assertThat(row1).containsExactly("1", "1.0", "5/12/24", "13:14:55", "5/12/24 13:14", "hello world");
+		assertThat(row2).containsExactly("2", "2.5", "8/8/23", "11:12:13", "8/8/23 11:12", "world hello");
+	}
+
+	@Test
+	void shouldBeAbleToReadMultipleTypesWithDatesAsIso() throws Exception {
+		var reader = new PoiItemReader<String[]>();
+		reader.setResource(new ClassPathResource("types.xls"));
+		reader.setRowMapper(new PassThroughRowMapper());
+		reader.setLinesToSkip(1); // Skip header
+		reader.setUserLocale(Locale.US); // Use a Locale to not be dependent on environment
+		reader.setDatesAsIso(true);
+		reader.afterPropertiesSet();
+
+		reader.open(new ExecutionContext());
+
+		var row1 = reader.read();
+		var row2 = reader.read();
+		assertThat(row1).containsExactly("1", "1.0", "2024-05-12", "13:14:55", "2024-05-12T13:14:55", "hello world");
+		assertThat(row2).containsExactly("2", "2.5", "2023-08-08", "11:12:13", "2023-08-08T11:12:13", "world hello");
+	}
+}

spring-batch-excel/src/test/java/org/springframework/batch/extensions/excel/streaming/StreamingXlsxTypesTests.java

@@ -43,7 +43,6 @@ void shouldBeAbleToReadMultipleTypes() throws Exception {
 		var row2 = reader.read();
 		assertThat(row1).containsExactly("1", "1.0", "5/12/24", "13:14:55", "5/12/24 13:14", "hello world");
 		assertThat(row2).containsExactly("2", "2.5", "8/8/23", "11:12:13", "8/8/23 11:12", "world hello");
-
 	}
 
 	@Test
@@ -60,9 +59,7 @@ void shouldBeAbleToReadMultipleTypesWithDatesAsIso() throws Exception {
 
 		var row1 = reader.read();
 		var row2 = reader.read();
-		assertThat(row1).containsExactly("1", "1.0", "2024-05-12T00:00:00", "1899-12-31T13:14:55", "2024-05-12T13:14:55", "hello world");
-		assertThat(row2).containsExactly("2", "2.5", "2023-08-08T00:00:00", "1899-12-31T11:12:13", "2023-08-08T11:12:13", "world hello");
-
+		assertThat(row1).containsExactly("1", "1.0", "2024-05-12", "13:14:55", "2024-05-12T13:14:55", "hello world");
+		assertThat(row2).containsExactly("2", "2.5", "2023-08-08", "11:12:13", "2023-08-08T11:12:13", "world hello");
 	}
-
 }