我正在尝试阅读Big XLSX文件。 Excel文件大约有500K行。我需要阅读第2列。
OPCPackage pkg;
pkg = OPCPackage.open("File path");
XSSFWorkbook myWorkBook = new XSSFWorkbook(pkg);
Sheet sheet = myWorkBook.getSheetAt(2);
Iterator<Row> rowIterator = sheet.iterator();
while (rowIterator.hasNext())
{
Row row = rowIterator.next();
if (row_num > ROW_ESCAPE)
{
Cell cell = row.getCell(2);
if (!cell.getStringCellValue().toString().trim().isEmpty())
{
System.out.println(cell.getStringCellValue().toString());
}
System.out.println("hi"+row_num);
}
row_num++;
}
打印到第39723行 之后它抛出以下异常
Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space
at java.util.regex.Matcher.<init>(Matcher.java:225)
at java.util.regex.Pattern.matcher(Pattern.java:1093)
at org.apache.poi.xssf.usermodel.XSSFRichTextString.utfDecode(XSSFRichTextString.java:482)
at org.apache.poi.xssf.usermodel.XSSFRichTextString.getString(XSSFRichTextString.java:297)
at org.apache.poi.xssf.usermodel.XSSFCell.getStringCellValue(XSSFCell.java:262)
at Main.get_titles(Main.java:484)
at Main.analyze_Importsheet(Main.java:461)
at Main.but_sel_imp_sheetActionPerformed(Main.java:220)
at Main.access$000(Main.java:40)
at Main$1.actionPerformed(Main.java:85)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
Main.java:484=if（！cell.getStringCellValue（）。toString（）。trim（）。isEmpty（）） 如果我删除该行并只打印行号，它可以正常工作。 我需要帮助如何获取col 2的字符串值。
答案 0 :(得分：3)
使用流 eventmodel API，而不是内存中的用户模型API。
答案 1 :(得分：0)
增加JVM的堆大小可能会修复OutOfMemoryError。有关如何增加JVM堆大小的信息，请参阅this stackoverflow post。
答案 2 :(得分：0)
最简单的方法（不使用读取逻辑）将增加堆大小。
如果这对您来说不是一个可行的选择，请使用流。 实际上，已经有一个方便的图书馆。
答案 3 :(得分：0)
您需要查看此https://github.com/monitorjbl/excel-streaming-reader
您可以像这样
InputStream is = new FileInputStream(new File("/path/to/workbook.xlsx"));
Workbook workbook = StreamingReader.builder()
.rowCacheSize(100) // number of rows to keep in memory (defaults to 10)
.bufferSize(4096) // buffer size to use when reading InputStream to file (defaults to 1024)
.open(is);
// InputStream or File for XLSX file (required)
答案 4 :(得分：0)
该库可从 Maven Central 获得，您也可以选择自行安装。
<!-- POI for parsing Excel files-->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>4.1.2</version>
</dependency>
<!-- POI-ooxml -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>4.1.2</version>
</dependency>
<!-- For reading very large Excel file -->
<dependency>
<groupId>com.monitorjbl</groupId>
<artifactId>xlsx-streamer</artifactId>
<version>2.1.0</version>
</dependency>
要使用它，请将其添加到您的 POM： 只需粘贴类名为 ReadLargeFile.java 的代码，即可见效，
import code.axis.properties.ConfigReader;
import com.monitorjbl.xlsx.StreamingReader;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.NumberToTextConverter;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.regex.Pattern;
public class ReadLargeFile {
public static void main(String[] args) {
try (InputStream inputStream = new FileInputStream(new File("C:/Users/Nischal/Desktop/Qualtiy Assurance of Data Clener/Extra Large Files/update_fileName01-26-2021-6-34-49.XLSX"))) { //FilePath from your device
Workbook workbook = StreamingReader.builder().rowCacheSize(200).bufferSize(4096).open(inputStream);
for (Sheet sheet : workbook) {
for (Row row : sheet) {
for (Cell cell : row) {
String cellValue = getStringCellValue(cell);
System.out.println(cellValue);
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
private static String getStringCellValue(Cell cell) {
try {
switch (cell.getCellType()) {
case FORMULA:
try {
return NumberToTextConverter.toText(cell.getNumericCellValue());
} catch (NumberFormatException e) {
return cell.getStringCellValue();
}
case NUMERIC:
return NumberToTextConverter.toText(cell.getNumericCellValue());
case STRING:
String cellValue = cell.getStringCellValue().trim();
String pattern = "\\^\\$?-?([1-9][0-9]{0,2}(,\\d{3})*(\\.\\d{0,2})?|[1-9]\\d*(\\.\\d{0,2})?|0(\\.\\d{0,2})?|(\\.\\d{1,2}))$|^-?\\$?([1-9]\\d{0,2}(,\\d{3})*(\\.\\d{0,2})?|[1-9]\\d*(\\.\\d{0,2})?|0(\\.\\d{0,2})?|(\\.\\d{1,2}))$|^\\(\\$?([1-9]\\d{0,2}(,\\d{3})*(\\.\\d{0,2})?|[1-9]\\d*(\\.\\d{0,2})?|0(\\.\\d{0,2})?|(\\.\\d{1,2}))\\)$";
if (((Pattern.compile(pattern)).matcher(cellValue)).find()) {
return cellValue.replaceAll("[^\\d.]", "");
}
return cellValue.trim();
case BOOLEAN:
return String.valueOf(cell.getBooleanCellValue());
case ERROR:
return null;
default:
return cell.getStringCellValue();
}
} catch (Exception e) {
if (e.getLocalizedMessage() != null && ConfigReader.isDisplayWarnLog())
return "";
}
return "";
}
}
无论excel文件多大，代码都会一一打印单元格值。