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[JAVA] 대용량 엑셀 반출 heavy excel export

POI를 이용한 JAVA대용량 EXPORT. 실제로 30만건까지 EXPORT해보았는데, 이상없이 EXPORT 된다. 원리는 임시 xlsx를 생성해놓고 openxml을 이용하여 파일로 작성한 후 덮어 쒸우는듯하다.
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   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
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package org.apache.poi.xssf.usermodel.examples;

import java.io.*;
import java.util.*;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

import org.apache.poi.ss.usermodel.DateUtil;
import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.ss.util.CellReference;
import org.apache.poi.xssf.usermodel.*;

/**
 * Demonstrates a workaround you can use to generate large workbooks and avoid OutOfMemory exception.
 *
 * The trick is as follows:
 * 1. create a template workbook, create sheets and global objects such as cell styles, number formats, etc.
 * 2. create an application that streams data in a text file
 * 3. Substitute the sheet in the template with the generated data
 *
 * 

* Since 3.8-beta3 POI provides a low-memory footprint SXSSF API which implementing the "BigGridDemo" strategy. * XSSF is an API-compatible streaming extension of XSSF to be used when * very large spreadsheets have to be produced, and heap space is limited. * SXSSF achieves its low memory footprint by limiting access to the rows that * are within a sliding window, while XSSF gives access to all rows in the * document. Older rows that are no longer in the window become inaccessible, * as they are written to the disk. *

* See * http://poi.apache.org/spreadsheet/how-to.html#sxssf. * * @author Yegor Kozlov */ public class BigGridDemo { private static final String XML_ENCODING = "UTF-8"; public static void main(String[] args) throws Exception { // Step 1. Create a template file. Setup sheets and workbook-level objects such as // cell styles, number formats, etc. XSSFWorkbook wb = new XSSFWorkbook(); XSSFSheet sheet = wb.createSheet("Big Grid"); Map styles = createStyles(wb); //name of the zip entry holding sheet data, e.g. /xl/worksheets/sheet1.xml String sheetRef = sheet.getPackagePart().getPartName().getName(); //save the template FileOutputStream os = new FileOutputStream("template.xlsx"); wb.write(os); os.close(); //Step 2. Generate XML file. File tmp = File.createTempFile("sheet", ".xml"); Writer fw = new OutputStreamWriter(new FileOutputStream(tmp), XML_ENCODING); generate(fw, styles); fw.close(); //Step 3. Substitute the template entry with the generated data FileOutputStream out = new FileOutputStream("big-grid.xlsx"); substitute(new File("template.xlsx"), tmp, sheetRef.substring(1), out); out.close(); } /** * Create a library of cell styles. */ private static Map createStyles(XSSFWorkbook wb){ Map styles = new HashMap(); XSSFDataFormat fmt = wb.createDataFormat(); XSSFCellStyle style1 = wb.createCellStyle(); style1.setAlignment(XSSFCellStyle.ALIGN_RIGHT); style1.setDataFormat(fmt.getFormat("0.0%")); styles.put("percent", style1); XSSFCellStyle style2 = wb.createCellStyle(); style2.setAlignment(XSSFCellStyle.ALIGN_CENTER); style2.setDataFormat(fmt.getFormat("0.0X")); styles.put("coeff", style2); XSSFCellStyle style3 = wb.createCellStyle(); style3.setAlignment(XSSFCellStyle.ALIGN_RIGHT); style3.setDataFormat(fmt.getFormat("$#,##0.00")); styles.put("currency", style3); XSSFCellStyle style4 = wb.createCellStyle(); style4.setAlignment(XSSFCellStyle.ALIGN_RIGHT); style4.setDataFormat(fmt.getFormat("mmm dd")); styles.put("date", style4); XSSFCellStyle style5 = wb.createCellStyle(); XSSFFont headerFont = wb.createFont(); headerFont.setBold(true); style5.setFillForegroundColor(IndexedColors.GREY_25_PERCENT.getIndex()); style5.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND); style5.setFont(headerFont); styles.put("header", style5); return styles; } private static void generate(Writer out, Map styles) throws Exception { Random rnd = new Random(); Calendar calendar = Calendar.getInstance(); SpreadsheetWriter sw = new SpreadsheetWriter(out); sw.beginSheet(); //insert header row sw.insertRow(0); int styleIndex = styles.get("header").getIndex(); sw.createCell(0, "Title", styleIndex); sw.createCell(1, "% Change", styleIndex); sw.createCell(2, "Ratio", styleIndex); sw.createCell(3, "Expenses", styleIndex); sw.createCell(4, "Date", styleIndex); sw.endRow(); //write data rows for (int rownum = 1; rownum < 100000; rownum++) { sw.insertRow(rownum); sw.createCell(0, "Hello, " + rownum + "!"); sw.createCell(1, (double)rnd.nextInt(100)/100, styles.get("percent").getIndex()); sw.createCell(2, (double)rnd.nextInt(10)/10, styles.get("coeff").getIndex()); sw.createCell(3, rnd.nextInt(10000), styles.get("currency").getIndex()); sw.createCell(4, calendar, styles.get("date").getIndex()); sw.endRow(); calendar.roll(Calendar.DAY_OF_YEAR, 1); } sw.endSheet(); } /** * * @param zipfile the template file * @param tmpfile the XML file with the sheet data * @param entry the name of the sheet entry to substitute, e.g. xl/worksheets/sheet1.xml * @param out the stream to write the result to */ private static void substitute(File zipfile, File tmpfile, String entry, OutputStream out) throws IOException { ZipFile zip = new ZipFile(zipfile); ZipOutputStream zos = new ZipOutputStream(out); @SuppressWarnings("unchecked") Enumeration en = (Enumeration) zip.entries(); while (en.hasMoreElements()) { ZipEntry ze = en.nextElement(); if(!ze.getName().equals(entry)){ zos.putNextEntry(new ZipEntry(ze.getName())); InputStream is = zip.getInputStream(ze); copyStream(is, zos); is.close(); } } zos.putNextEntry(new ZipEntry(entry)); InputStream is = new FileInputStream(tmpfile); copyStream(is, zos); is.close(); zos.close(); } private static void copyStream(InputStream in, OutputStream out) throws IOException { byte[] chunk = new byte[1024]; int count; while ((count = in.read(chunk)) >=0 ) { out.write(chunk,0,count); } } /** * Writes spreadsheet data in a Writer. * (YK: in future it may evolve in a full-featured API for streaming data in Excel) */ public static class SpreadsheetWriter { private final Writer _out; private int _rownum; public SpreadsheetWriter(Writer out){ _out = out; } public void beginSheet() throws IOException { _out.write("" + "" ); _out.write("\n"); } public void endSheet() throws IOException { _out.write(""); _out.write(""); } /** * Insert a new row * * @param rownum 0-based row number */ public void insertRow(int rownum) throws IOException { _out.write("\n"); this._rownum = rownum; } /** * Insert row end marker */ public void endRow() throws IOException { _out.write("\n"); } public void createCell(int columnIndex, String value, int styleIndex) throws IOException { String ref = new CellReference(_rownum, columnIndex).formatAsString(); _out.write(""); _out.write(""+value+""); _out.write(""); } public void createCell(int columnIndex, String value) throws IOException { createCell(columnIndex, value, -1); } public void createCell(int columnIndex, double value, int styleIndex) throws IOException { String ref = new CellReference(_rownum, columnIndex).formatAsString(); _out.write(""); _out.write(""+value+""); _out.write(""); } public void createCell(int columnIndex, double value) throws IOException { createCell(columnIndex, value, -1); } public void createCell(int columnIndex, Calendar value, int styleIndex) throws IOException { createCell(columnIndex, DateUtil.getExcelDate(value, false), styleIndex); } } }
소스 출처는 http://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/xssf/usermodel/examples/BigGridDemo.java