POI读写海量Excel（详细解读）

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目前处理Excel的开源javaAPI主要有两种，一是Jxl（Java Excel API）,Jxl只支持Excel2003以下的版本。另外一种是Apache的Jakarta POI,相比于Jxl,POI对微软办公文档的支持更加强大，但是它使用复杂，上手慢。POI可支持更高的Excel版本2007。对Excel的读取，POI有两种模式，一是用户模式，这种方式同Jxl的使用很类似，使用简单，都是将文件一次性读到内存，文件小的时候，没有什么问题，当文件大的时候，就会出现OutOfMemory的内存溢出问题。第二种是事件驱动模式，拿Excel2007来说，其内容采用XML的格式来存储，所以处理excel就是解析XML，而目前使用事件驱动模式解析XML的API是SAX(Simple API for XML)，这种模型在读取XML文档时，并没有将整个文档读入内存，而是按顺序将整个文档解析完，在解析过程中，会主动产生事件交给程序中相应的处理函数来处理当前内容。因此这种方式对系统资源要求不高，可以处理海量数据。笔者曾经做过测试，这种方法处理一千万条，每条五列的数据花费大约11分钟。可见处理海量数据的文件事件驱动是一个很好的方式。而本文中用到的AbstractExcel2003Reader、AbstractExcel2007Reader对Excel的读取都是采用这种POI的事件驱动模式。至于Excel的写操作，对较高版本的Excel2007，POI提供了很好的支持，主要流程是第一步构建工作薄和电子表格对象，第二步在一个流中构建文本文件，第三步使用流中产生的数据替换模板中的电子表格。这种方式也可以处理海量数据文件。AbstractExcel2007Writer就是使用这种方式进行写操作。对于写入较低版本的Excel2003，POI使用了用户模式来处理，就是将整个文档加载进内存，如果数据量大的话就会出现内存溢出的问题，Excel2003Writer就是使用这种方式。据笔者的测试，如果数据量大于3万条，每条8列的话，就会报OutOfMemory的错误。Excel2003中每个电子表格的记录数必须在65536以下，否则就会发生异常。目前还没有好的解决方案，建议对于海量数据写入操作，尽量使用Excel2007。 /**

* 抽象Excel2003读取器，通过实现HSSFListener监听器，采用事件驱动模式解析excel2003 * 中的内容，遇到特定事件才会触发，大大减少了内存的使用。 * */

public class Excel2003Reader implements HSSFListener{ private int minColumns = -1; private POIFSFileSystem fs; private int lastRowNumber; private int lastColumnNumber; /** Should we output the formula, or the value it has? */ private boolean outputFormulaValues = true; /** For parsing Formulas */ private SheetRecordCollectingListener workbookBuildingListener; //excel2003工作薄 private HSSFWorkbook stubWorkbook; // Records we pick up as we process private SSTRecord sstRecord;

private FormatTrackingHSSFListener formatListener; //表索引

private int sheetIndex = -1;

private BoundSheetRecord[] orderedBSRs; @SuppressWarnings(\

private ArrayList boundSheetRecords = new ArrayList(); // For handling formulas with string results private int nextRow; private int nextColumn;

private boolean outputNextStringRecord; //当前行

private int curRow = 0;

//存储行记录的容器

private List rowlist = new ArrayList();; @SuppressWarnings( \private String sheetName;

private IRowReader rowReader;

public void setRowReader(IRowReader rowReader){ this.rowReader = rowReader; } /**

* 遍历excel下所有的sheet * @throws IOException */

public void process(String fileName) throws IOException { this.fs = new POIFSFileSystem(new FileInputStream(fileName)); MissingRecordAwareHSSFListener listener = new MissingRecordAwareHSSFListener( this); formatListener = new FormatTrackingHSSFListener(listener); HSSFEventFactory factory = new HSSFEventFactory(); HSSFRequest request = new HSSFRequest(); if (outputFormulaValues) { request.addListenerForAllRecords(formatListener); } else { workbookBuildingListener = new SheetRecordCollectingListener( formatListener); request.addListenerForAllRecords(workbookBuildingListener); }

factory.processWorkbookEvents(request, fs); } /**

* HSSFListener 监听方法，处理 Record */

@SuppressWarnings(\

public void processRecord(Record record) { int thisRow = -1; int thisColumn = -1; String thisStr = null; String value = null; switch (record.getSid()) { case BoundSheetRecord.sid: boundSheetRecords.add(record); break; case BOFRecord.sid: BOFRecord br = (BOFRecord) record; if (br.getType() == BOFRecord.TYPE_WORKSHEET) { // 如果有需要，则建立子工作薄 if (workbookBuildingListener != null && stubWorkbook == null) { stubWorkbook = workbookBuildingListener .getStubHSSFWorkbook(); } sheetIndex++; if (orderedBSRs == null) { orderedBSRs = BoundSheetRecord .orderByBofPosition(boundSheetRecords); } sheetName = orderedBSRs[sheetIndex].getSheetname(); } break; case SSTRecord.sid: sstRecord = (SSTRecord) record; break; case BlankRecord.sid: BlankRecord brec = (BlankRecord) record; thisRow = brec.getRow(); thisColumn = brec.getColumn(); thisStr = \ rowlist.add(thisColumn, thisStr);

break;

case BoolErrRecord.sid: //单元格为布尔类型 BoolErrRecord berec = (BoolErrRecord) record; thisRow = berec.getRow(); thisColumn = berec.getColumn(); thisStr = berec.getBooleanValue()+\ rowlist.add(thisColumn, thisStr); break;

case FormulaRecord.sid: //单元格为公式类型 FormulaRecord frec = (FormulaRecord) record; thisRow = frec.getRow(); thisColumn = frec.getColumn(); if (outputFormulaValues) { if (Double.isNaN(frec.getValue())) { // Formula result is a string // This is stored in the next record outputNextStringRecord = true; nextRow = frec.getRow(); nextColumn = frec.getColumn(); } else { thisStr = formatListener.formatNumberDateCell(frec); } } else { thisStr = '\ frec.getParsedExpression()) + '\ } rowlist.add(thisColumn,thisStr); break;

case StringRecord.sid://单元格中公式的字符串 if (outputNextStringRecord) { // String for formula StringRecord srec = (StringRecord) record; thisStr = srec.getString(); thisRow = nextRow; thisColumn = nextColumn; outputNextStringRecord = false; } break;

case LabelRecord.sid: LabelRecord lrec = (LabelRecord) record; curRow = thisRow = lrec.getRow(); thisColumn = lrec.getColumn(); value = lrec.getValue().trim();

}

value = value.equals(\ this.rowlist.add(thisColumn, value); break;

case LabelSSTRecord.sid: //单元格为字符串类型 LabelSSTRecord lsrec = (LabelSSTRecord) record; curRow = thisRow = lsrec.getRow(); thisColumn = lsrec.getColumn(); if (sstRecord == null) { rowlist.add(thisColumn, \ } else { value = sstRecord .getString(lsrec.getSSTIndex()).toString().trim(); value = value.equals(\ rowlist.add(thisColumn,value); } break;

case NumberRecord.sid: //单元格为数字类型 NumberRecord numrec = (NumberRecord) record; curRow = thisRow = numrec.getRow(); thisColumn = numrec.getColumn(); value = formatListener.formatNumberDateCell(numrec).trim(); value = value.equals(\ // 向容器加入列值 rowlist.add(thisColumn, value); break; default: break;

// 遇到新行的操作

if (thisRow != -1 && thisRow != lastRowNumber) { lastColumnNumber = -1; }

// 空值的操作

if (record instanceof MissingCellDummyRecord) { MissingCellDummyRecord mc = (MissingCellDummyRecord) record; curRow = thisRow = mc.getRow(); thisColumn = mc.getColumn(); rowlist.add(thisColumn,\}

// 更新行和列的值 if (thisRow > -1)

} /**

}

lastRowNumber = thisRow; if (thisColumn > -1) lastColumnNumber = thisColumn;

// 行结束时的操作

if (record instanceof LastCellOfRowDummyRecord) { if (minColumns > 0) { // 列值重新置空 if (lastColumnNumber == -1) { lastColumnNumber = 0; } } lastColumnNumber = -1; }

// 每行结束时，调用getRows() 方法 rowReader.getRows(sheetIndex,curRow, rowlist);

// 清空容器 rowlist.clear();

* 抽象Excel2007读取器，excel2007的底层数据结构是xml文件，采用SAX的事件驱动的方法解析

* xml，需要继承DefaultHandler，在遇到文件内容时，事件会触发，这种做法可以大大降低

* 内存的耗费，特别使用于大数据量的文件。 * */

public class Excel2007Reader extends DefaultHandler { //共享字符串表 private SharedStringsTable sst;

//上一次的内容

private String lastContents; private boolean nextIsString;

private int sheetIndex = -1;

private List rowlist = new ArrayList(); //当前行

private int curRow = 0; //当前列

private int curCol = 0;

//日期标志

private boolean dateFlag; //数字标志

private boolean numberFlag;

private boolean isTElement;

private IRowReader rowReader;

public void setRowReader(IRowReader rowReader){ this.rowReader = rowReader; }

/**只遍历一个电子表格，其中sheetId为要遍历的sheet索引，从1开始，1-3 * @param filename * @param sheetId * @throws Exception */

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

// 根据 rId# 或 rSheet# 查找sheet

InputStream sheet2 = r.getSheet(\sheetIndex++;

InputSource sheetSource = new InputSource(sheet2); parser.parse(sheetSource); sheet2.close();

/**

* 遍历工作簿中所有的电子表格 * @param filename * @throws Exception */

public void process(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()) { curRow = 0; sheetIndex++; InputStream sheet = sheets.next(); InputSource sheetSource = new InputSource(sheet); parser.parse(sheetSource); sheet.close(); }

public XMLReader fetchSheetParser(SharedStringsTable sst) throws SAXException { XMLReader parser = XMLReaderFactory .createXMLReader(\ this.sst = sst; parser.setContentHandler(this); return parser; }

public void startElement(String uri, String localName, String name, Attributes attributes) throws SAXException {

// c => 单元格

if (\

// 如果下一个元素是 SST 的索引，则将nextIsString标记为true String cellType = attributes.getValue(\if (\ nextIsString = true; } else { nextIsString = false; }

//日期格式

String cellDateType = attributes.getValue(\if (\ dateFlag = true; } else { dateFlag = false; }

String cellNumberType = attributes.getValue(\if(\ numberFlag = true; } else { numberFlag = false; }

}

//当元素为t时 if(\ isTElement = true; } else { isTElement = false; }

// 置空

lastContents = \

public void endElement(String uri, String localName, String name) throws SAXException {

// 根据SST的索引值的到单元格的真正要存储的字符串 // 这时characters()方法可能会被调用多次 if (nextIsString) { try { int idx = Integer.parseInt(lastContents); lastContents = new XSSFRichTextString(sst.getEntryAt(idx)) .toString(); } catch (Exception e) { } }

//t元素也包含字符串 if(isTElement){ String value = lastContents.trim(); rowlist.add(curCol, value); curCol++; isTElement = false; // v => 单元格的值，如果单元格是字符串则v标签的值为该字符串在SST中的索引 // 将单元格内容加入rowlist中，在这之前先去掉字符串前后的空白符 } else if (\ String value = lastContents.trim(); value = value.equals(\ //日期格式处理 if(dateFlag){ Date date = HSSFDateUtil.getJavaDate(Double.valueOf(value)); SimpleDateFormat dateFormat = new SimpleDateFormat( \

value = dateFormat.format(date); } //数字类型处理 if(numberFlag){ BigDecimal bd = new BigDecimal(value); value = bd.setScale(3,BigDecimal.ROUND_UP).toString(); } rowlist.add(curCol, value); curCol++; }else {

//如果标签名称为 row ，这说明已到行尾，调用 optRows() 方法 if (name.equals(\ rowReader.getRows(sheetIndex,curRow,rowlist); rowlist.clear(); curRow++; curCol = 0; } } } public void characters(char[] ch, int start, int length) throws SAXException { //得到单元格内容的值 lastContents += new String(ch, start, length); } }

public class ExcelReaderUtil {

//excel2003扩展名

public static final String EXCEL03_EXTENSION = \

//excel2007扩展名

public static final String EXCEL07_EXTENSION = \ /**

* 读取Excel文件，可能是03也可能是07版本 * @param excel03 * @param excel07 * @param fileName * @throws Exception */

public static void readExcel(IRowReader reader,String fileName) throws Exception{ // 处理excel2003文件

if (fileName.endsWith(EXCEL03_EXTENSION)){ Excel2003Reader excel03 = new Excel2003Reader(); excel03.setRowReader(reader); excel03.process(fileName); // 处理excel2007文件

} else if (fileName.endsWith(EXCEL07_EXTENSION)){ Excel2007Reader excel07 = new Excel2007Reader(); excel07.setRowReader(reader); excel07.process(fileName); } else {

throw new Exception(\文件格式错误，fileName的扩展名只能是xls或xlsx。\ } } }

public interface IRowReader { /**业务逻辑实现方法 * @param sheetIndex * @param curRow * @param rowlist */ public void getRows(int sheetIndex,int curRow, List rowlist); }

public class RowReader implements IRowReader{ /* 业务逻辑实现方法 * @see com.eprosun.util.excel.IRowReader#getRows(int, int, java.util.List) */ public void getRows(int sheetIndex, int curRow, List rowlist) { // TODO Auto-generated method stub System.out.print(curRow+\ for (int i = 0; i < rowlist.size(); i++) { System.out.print(rowlist.get(i) + \ } System.out.println(); } }

public class Main {

public static void main(String[] args) throws Exception { IRowReader reader = new RowReader(); //ExcelReaderUtil.readExcel(reader, \ ExcelReaderUtil.readExcel(reader, \ } }

public class Excel2003Writer { /** * @param args */ public static void main(String[] args) { try{ System.out.println(\开始写入excel2003....\ writeExcel(\

} /**

System.out.println(\写完xcel2003\} catch (IOException e) { }

* 写入excel并填充内容,一个sheet只能写65536行以下，超出会报异常，写入时建议使用AbstractExcel2007Writer * @param fileName * @throws IOException */ public static void writeExcel(String fileName) throws IOException{

// 创建excel2003对象

Workbook wb = new HSSFWorkbook();

// 设置文件放置路径和文件名

FileOutputStream fileOut = new FileOutputStream(fileName); // 创建新的表单

Sheet sheet = wb.createSheet(\ // 创建新行

for(int i=0;i<20000;i++){ Row row = sheet.createRow(i); // 创建单元格 Cell cell = row.createCell(0);

// 设置单元格值 cell.setCellValue(1); row.createCell(1).setCellValue(1+i); row.createCell(2).setCellValue(true); row.createCell(3).setCellValue(0.43d); row.createCell(4).setCellValue('d'); row.createCell(5).setCellValue(\ row.createCell(6).setCellValue(\第七列\ row.createCell(7).setCellValue(\第八列\ } wb.write(fileOut); fileOut.close(); } } /**

* 抽象excel2007读入器，先构建.xlsx一张模板，改写模板中的sheet.xml,使用这种方法 * 写入.xlsx文件，不需要太大的内存 * */

public abstract class AbstractExcel2007Writer { private SpreadsheetWriter sw; /**

* 写入电子表格的主要流程 * @param fileName * @throws Exception */

public void process(String fileName) throws Exception{

// 建立工作簿和电子表格对象

XSSFWorkbook wb = new XSSFWorkbook(); XSSFSheet sheet = wb.createSheet(\

// 持有电子表格数据的xml文件名例如 /xl/worksheets/sheet1.xml String sheetRef = sheet.getPackagePart().getPartName().getName(); // 保存模板

FileOutputStream os = new FileOutputStream(\wb.write(os); os.close();

// 生成xml文件

} /**

File tmp = File.createTempFile(\Writer fw = new FileWriter(tmp); sw = new SpreadsheetWriter(fw); generate(); fw.close();

// 使用产生的数据替换模板

File templateFile = new File(\

FileOutputStream out = new FileOutputStream(fileName); substitute(templateFile, tmp, sheetRef.substring(1), out); out.close();

//删除文件之前调用一下垃圾回收器，否则无法删除模板文件 System.gc();

// 删除临时模板文件

if (templateFile.isFile()&&templateFile.exists()){ templateFile.delete(); }

* 类使用者应该使用此方法进行写操作 * @throws Exception */

public abstract void generate() throws Exception; public void beginSheet() throws IOException { sw.beginSheet(); }

public void insertRow(int rowNum) throws IOException { sw.insertRow(rowNum); }

public void createCell(int columnIndex, String value) throws IOException { sw.createCell(columnIndex, value, -1); }

public void createCell(int columnIndex, double value) throws IOException { sw.createCell(columnIndex, value, -1); }

public void endRow() throws IOException { sw.endRow(); }

public void endSheet() throws IOException { 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(\

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); } }

/**

* 在写入器中写入电子表格 * */ public static class SpreadsheetWriter { private final Writer _out; private int _rownum; private static String LINE_SEPARATOR = System.getProperty(\ public SpreadsheetWriter(Writer out) { _out = out; } public void beginSheet() throws IOException { _out.write(\ + xmlns=\\\ _out.write(\ } public void endSheet() throws IOException { _out.write(\ _out.write(\ } /** * 插入新行 * * @param rownum 以0开始 */ public void insertRow(int rownum) throws IOException { _out.write(\ this._rownum = rownum; } /** * 插入行结束标志 */ public void endRow() throws IOException { _out.write(\ } /** * 插入新列

* @param columnIndex * @param value * @param styleIndex * @throws IOException */

public void createCell(int columnIndex, String value, int styleIndex) throws IOException { String ref = new CellReference(_rownum, columnIndex) .formatAsString(); _out.write(\ if (styleIndex != -1) _out.write(\ _out.write(\ _out.write(\ _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(\ if (styleIndex != -1) _out.write(\ _out.write(\ _out.write(\ _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); }

} }

public class Excel2007WriterImpl extends AbstractExcel2007Writer{ /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { // TODO Auto-generated method stub System.out.println(\ long start = System.currentTimeMillis();

} /*

//构建excel2007写入器

AbstractExcel2007Writer excel07Writer = new Excel2007WriterImpl(); //调用处理方法

excel07Writer.process(\long end = System.currentTimeMillis();

System.out.println(\

* 可根据需求重写此方法，对于单元格的小数或者日期格式，会出现精度问题或者日期格式转化问题，建议使用字符串插入方法 * @see com.excel.ver2.AbstractExcel2007Writer#generate() */ @Override public void generate()throws Exception { //电子表格开始 beginSheet();

for (int rownum = 0; rownum < 100; rownum++) { //插入新行

insertRow(rownum);

//建立新单元格,索引值从0开始,表示第一列 createCell(0, \中国<\ createCell(1, 34343.123456789); createCell(2, \ createCell(3, \

createCell(4, \ createCell(5, \ createCell(6, \

//结束行 endRow(); }

//电子表格结束 endSheet(); } }

public class XMLEncoder {

private static final String[] xmlCode = new String[256];

static {

// Special characters xmlCode['\\''] = \

xmlCode['\\\ xmlCode['&'] = \ xmlCode['<'] = \ xmlCode['>'] = \ }

/** *