bellwoの例では、完全なExcelファイル（私にとっては60Mo）を「メモリ不足」の問題なしにオブジェクトのリストに解析し、正常に動作する完全なコードを追加します。
import java.util.ArrayList;
import java.util.List;
class DistinctByProperty {
private static OPCPackage xlsxPackage = null;
private static PrintStream output= System.out;
private static List<MassUpdateMonitoringRow> resultMapping = new ArrayList<>();
public static void main(String[] args) throws IOException {
File file = new File("C:\\Users\\aberguig032018\\Downloads\\your_excel.xlsx");
double bytes = file.length();
double kilobytes = (bytes / 1024);
double megabytes = (kilobytes / 1024);
System.out.println("Size "+megabytes);
parseExcel(file);
}
public static void parseExcel(File file) throws IOException {
try {
xlsxPackage = OPCPackage.open(file.getAbsolutePath(), PackageAccess.READ);
ReadOnlySharedStringsTable strings = new ReadOnlySharedStringsTable(xlsxPackage);
XSSFReader xssfReader = new XSSFReader(xlsxPackage);
StylesTable styles = xssfReader.getStylesTable();
XSSFReader.SheetIterator iter = (XSSFReader.SheetIterator) xssfReader.getSheetsData();
int index = 0;
while (iter.hasNext()) {
try (InputStream stream = iter.next()) {
String sheetName = iter.getSheetName();
output.println();
output.println(sheetName + " [index=" + index + "]:");
processSheet(styles, strings, new MappingFromXml(resultMapping), stream);
}
++index;
}
} catch (InvalidFormatException e) {
e.printStackTrace();
} catch (OpenXML4JException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
}
}
private static void processSheet(StylesTable styles, ReadOnlySharedStringsTable strings, MappingFromXml mappingFromXml, InputStream sheetInputStream) throws IOException, SAXException {
DataFormatter formatter = new DataFormatter();
InputSource sheetSource = new InputSource(sheetInputStream);
try {
XMLReader sheetParser = SAXHelper.newXMLReader();
ContentHandler handler = new XSSFSheetXMLHandler(
styles, null, strings, mappingFromXml, formatter, false);
sheetParser.setContentHandler(handler);
sheetParser.parse(sheetSource);
System.out.println("Size of Array "+resultMapping.size());
} catch(ParserConfigurationException e) {
throw new RuntimeException("SAX parser appears to be broken - " + e.getMessage());
}
}
}
実装する呼び出しを追加する必要があります
SheetContentsHandler
import com.sun.org.apache.xpath.internal.operations.Bool;
import org.apache.poi.ss.util.CellAddress;
import org.apache.poi.ss.util.CellReference;
import org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler.SheetContentsHandler;
import org.apache.poi.xssf.usermodel.XSSFComment;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.List;
public class MappingFromXml implements SheetContentsHandler {
private List<myObject> result = new ArrayList<>();
private myObject myObject = null;
private int lineNumber = 0;
/**
* Number of columns to read starting with leftmost
*/
private int minColumns = 25;
/**
* Destination for data
*/
private PrintStream output = System.out;
public MappingFromXml(List<myObject> list) {
this.result = list;
}
@Override
public void startRow(int i) {
output.println("iii " + i);
lineNumber = i;
myObject = new myObject();
}
@Override
public void endRow(int i) {
output.println("jjj " + i);
result.add(myObject);
myObject = null;
}
@Override
public void cell(String cellReference, String formattedValue, XSSFComment comment) {
int columnIndex = (new CellReference(cellReference)).getCol();
if(lineNumber > 0){
switch (columnIndex) {
case 0: {//Tech id
if (formattedValue != null && !formattedValue.isEmpty())
myObject.setId(Integer.parseInt(formattedValue));
}
break;
//TODO add other cell
}
}
}
@Override
public void headerFooter(String s, boolean b, String s1) {
}
}
詳細については、このリンクをご覧ください