대용량 Excel 처리 - POI event api example

import java.io.InputStream;
import java.util.Iterator;

import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.xssf.eventusermodel.XSSFReader;
import org.apache.poi.xssf.model.SharedStringsTable;
import org.apache.poi.xssf.usermodel.XSSFRichTextString;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;

public class ExampleEventUserModel {
	public void processOneSheet(String filename) throws Exception {
		OPCPackage pkg = OPCPackage.open(filename);
		XSSFReader r = new XSSFReader( pkg );
		SharedStringsTable sst = r.getSharedStringsTable();

		XMLReader parser = fetchSheetParser(sst);

		// rId2 found by processing the Workbook
		// Seems to either be rId# or rSheet#
		InputStream sheet2 = r.getSheet("rId1");
		InputSource sheetSource = new InputSource(sheet2);
		parser.parse(sheetSource);
		sheet2.close();
	}

	public void processAllSheets(String filename) throws Exception {
		OPCPackage pkg = OPCPackage.open(filename);
		XSSFReader r = new XSSFReader( pkg );
		SharedStringsTable sst = r.getSharedStringsTable();
		
		XMLReader parser = fetchSheetParser(sst);

		Iterator sheets = r.getSheetsData();
		while(sheets.hasNext()) {
			System.out.println("Processing new sheet:\n");
			InputStream sheet = sheets.next();
			InputSource sheetSource = new InputSource(sheet);
			parser.parse(sheetSource);
			sheet.close();
			System.out.println("");
		}
	}

	public XMLReader fetchSheetParser(SharedStringsTable sst) throws SAXException {
		XMLReader parser =
			XMLReaderFactory.createXMLReader(
					"org.apache.xerces.parsers.SAXParser"
			);
		ContentHandler handler = new SheetHandler(sst);
		parser.setContentHandler(handler);
		return parser;
	}

	/** 
	 * See org.xml.sax.helpers.DefaultHandler javadocs 
	 */
	private static class SheetHandler extends DefaultHandler {
		private SharedStringsTable sst;
		private String lastContents;
		private boolean nextIsString;
		
		private SheetHandler(SharedStringsTable sst) {
			this.sst = sst;
		}
		
		public void startElement(String uri, String localName, String name,
				Attributes attributes) throws SAXException {
			// c => cell
			if(name.equals("c")) {
				// Print the cell reference
				System.out.print(attributes.getValue("r") + " - ");
				// Figure out if the value is an index in the SST
				String cellType = attributes.getValue("t");
				if(cellType != null && cellType.equals("s")) {
					nextIsString = true;
				} else {
					nextIsString = false;
				}
			}
			// Clear contents cache
			lastContents = "";
		}
		
		public void endElement(String uri, String localName, String name)
				throws SAXException {
			// Process the last contents as required.
			// Do now, as characters() may be called more than once
			if(nextIsString) {
				int idx = Integer.parseInt(lastContents);
				lastContents = new XSSFRichTextString(sst.getEntryAt(idx)).toString();
            nextIsString = false;
			}

			// v => contents of a cell
			// Output after we've seen the string contents
			if(name.equals("v")) {
				System.out.println(lastContents);
			}
		}

		public void characters(char[] ch, int start, int length)
				throws SAXException {
			lastContents += new String(ch, start, length);
		}
	}
	
	public static void main(String[] args) throws Exception {
		args = new String[] {"D:/EXPORT/t1_200mb_2.xls"};
		ExampleEventUserModel e = new ExampleEventUserModel();
		e.processOneSheet(args[0]);
		//howto.processAllSheets(args[0]);
	}
}