之前写过一篇关于如何导出大数据的博客，最近因为工作需要，又有导入的需求。网上查了很多资料，后来发现POI提供了解决方案，大致思路是，excel2007之后，其实是由xml组成的，把excel的扩展名改成zip,再解压，就能看到里面的xml。主要有两类xml，一类是存储常量的xml，名字叫 shareStrings.xml，大至如下：
<?xml version="1.0" encoding="utf-8"?>
<sst xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" count="38" uniqueCount="26">
<si>
<t>类型</t>
</si>
<si>
<t>数量</t>
</si>
<si>
<t>abdefga</t>
<phoneticPr fontId="1" type="noConversion"/>
</si>
</sst>
另一类是sheet对应的xml，一个sheet对应的一个xml,大致如下：
<?xml version="1.0" encoding="utf-8"?>
<worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:x14ac="http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac" mc:Ignorable="x14ac">
<dimension ref="A1:N5"/>
<sheetViews>
<sheetView tabSelected="1" topLeftCell="C1" workbookViewId="0">
<selection activeCell="K15" sqref="K15"/>
</sheetView>
</sheetViews>
<sheetFormatPr defaultRowHeight="13.5" x14ac:dyDescent="0.15"/>
<cols>
<col min="1" max="2" width="9" style="3"/>
<col min="3" max="3" width="24.375" style="3" customWidth="1"/>
<col min="4" max="4" width="9" style="3"/>
</cols>
<sheetData>
<row r="1" spans="1:14" x14ac:dyDescent="0.15">
<c r="A1" s="3" t="s">
<v>0</v>
</c>
<c r="B1" s="3" t="s">
<v>1</v>
</c>
</row>
</sheetData>
<phoneticPr fontId="1" type="noConversion"/>
<pageMargins left="0.7" right="0.7" top="0.75" bottom="0.75" header="0.3" footer="0.3"/>
<pageSetup paperSize="9" orientation="portrait" r:id="rId1"/>
</worksheet>
poi提供了解析xml的示例,这种通过流的方式读取,是不会内存溢出的,本地测试30万数据没有问题，叫做XLSX2CSV.java，我是从3.9的版本中找到的，这已经是一个很老的版本了，在以后的版本中，应该也能找到，我修改了下，大致可以完成，多线程的处理，把代码放这里，以防以后用到
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.apache.poi.openxml4j.exceptions.OpenXML4JException;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.openxml4j.opc.PackageAccess;
import org.apache.poi.ss.usermodel.BuiltinFormats;
import org.apache.poi.ss.usermodel.DataFormatter;
import org.apache.poi.xssf.eventusermodel.ReadOnlySharedStringsTable;
import org.apache.poi.xssf.eventusermodel.XSSFReader;
import org.apache.poi.xssf.model.StylesTable;
import org.apache.poi.xssf.usermodel.XSSFCellStyle;
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;
/**
* A rudimentary XLSX -> CSV processor modeled on the
* POI sample program XLS2CSVmra by Nick Burch from the
* package org.apache.poi.hssf.eventusermodel.examples.
* Unlike the HSSF version, this one completely ignores
* missing rows.
* <p/>
* Data sheets are read using a SAX parser to keep the
* memory footprint relatively small, so this should be
* able to read enormous workbooks. The styles table and
* the shared-string table must be kept in memory. The
* standard POI styles table class is used, but a custom
* (read-only) class is used for the shared string table
* because the standard POI SharedStringsTable grows very
* quickly with the number of unique strings.
* <p/>
* Thanks to Eric Smith for a patch that fixes a problem
* triggered by cells with multiple "t" elements, which is
* how Excel represents different formats (e.g., one word
* plain and one word bold).
*
* @author Chris Lott
*/
public class CopyOfXLSX2CSV {
private static final Logger logger = new Logger(CopyOfXLSX2CSV.class);
/**
* The type of the data value is indicated by an attribute on the cell.
* The value is usually in a "v" element within the cell.
*/
enum xssfDataType {
BOOL,
ERROR,
FORMULA,
INLINESTR,
SSTINDEX,
NUMBER,
}
class CommonException extends RuntimeException {
/**
*
*/
private static final long serialVersionUID = 1L;
private String code;
private String desc;
public CommonException(String code, String desc) {
this.code = code;
this.desc = desc;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
@Override
public String getMessage() {
return desc;
}
}
/**
* Derived from http://poi.apache.org/spreadsheet/how-to.html#xssf_sax_api
* <p/>
* Also see Standard ECMA-376, 1st edition, part 4, pages 1928ff, at
* http://www.ecma-international.org/publications/standards/Ecma-376.htm
* <p/>
* A web-friendly version is http://openiso.org/Ecma/376/Part4
*/
class MyXSSFSheetHandler extends DefaultHandler {
/**
* Table with styles
*/
private StylesTable stylesTable;
/**
* Table with unique strings
*/
private ReadOnlySharedStringsTable sharedStringsTable;
/**
* Destination for data
*/
private final ExcelDealAction action;
/**
* Number of columns to read starting with leftmost
*/
private final int minColumnCount;
// Set when V start element is seen
private boolean vIsOpen;
// Set when cell start element is seen;
// used when cell close element is seen.
private xssfDataType nextDataType;
// Used to format numeric cell values.
private short formatIndex;
private String formatString;
private final DataFormatter formatter;
private int thisColumn = -1;
// The last column printed to the output stream
private int lastColumnNumber = -1;
// Gathers characters as they are seen.
private StringBuffer value;
private Integer dealSize;
private String[] row;
private List<String[]> data;
//线程池
private ExecutorService fixedThreadPool ;
//是否只取第一行
private boolean isFirstRow;
private int beginSize=0;
/**
* Accepts objects needed while parsing.
*
* @param styles Table of styles
* @param strings Table of shared strings
* @param cols Minimum number of columns to show
* @param target Sink for output
*/
public MyXSSFSheetHandler(
StylesTable styles,
ReadOnlySharedStringsTable strings,
int cols,
ExcelDealAction action,
Integer dealSize,boolean isFirstRow) {
this.stylesTable = styles;
this.sharedStringsTable = strings;
this.minColumnCount = cols;
this.action = action;
this.value = new StringBuffer();
this.nextDataType = xssfDataType.NUMBER;
this.formatter = new DataFormatter();
this.dealSize=dealSize;
this.isFirstRow=isFirstRow;
this.row=new String[cols];
data=new ArrayList<String[]>();
int threadno=isFirstRow?1:Runtime.getRuntime().availableProcessors();
fixedThreadPool=Executors.newFixedThreadPool(threadno);
logger.info("线程池的初始化数据为:",threadno);
beginSize=0;
}
/*
* (non-Javadoc)
* @see org.xml.sax.helpers.DefaultHandler#startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
*/
public void startElement(String uri, String localName, String name,
Attributes attributes) throws SAXException {
if ("inlineStr".equals(name) || "v".equals(name)) {
vIsOpen = true;
// Clear contents cache
value.setLength(0);
}
// c => cell
else if ("c".equals(name)) {
// Get the cell reference
String r = attributes.getValue("r");
int firstDigit = -1;
for (int c = 0; c < r.length(); ++c) {
if (Character.isDigit(r.charAt(c))) {
firstDigit = c;
break;
}
}
thisColumn = nameToColumn(r.substring(0, firstDigit));
// Set up defaults.
this.nextDataType = xssfDataType.NUMBER;
this.formatIndex = -1;
this.formatString = null;
String cellType = attributes.getValue("t");
String cellStyleStr = attributes.getValue("s");
if ("b".equals(cellType))
nextDataType = xssfDataType.BOOL;
else if ("e".equals(cellType))
nextDataType = xssfDataType.ERROR;
else if ("inlineStr".equals(cellType))
nextDataType = xssfDataType.INLINESTR;
else if ("s".equals(cellType))
nextDataType = xssfDataType.SSTINDEX;
else if ("str".equals(cellType))
nextDataType = xssfDataType.FORMULA;
else if (cellStyleStr != null) {
// It's a number, but almost certainly one
// with a special style or format
int styleIndex = Integer.parseInt(cellStyleStr);
XSSFCellStyle style = stylesTable.getStyleAt(styleIndex);
this.formatIndex = style.getDataFormat();
this.formatString = style.getDataFormatString();
if (this.formatString == null)
this.formatString = BuiltinFormats.getBuiltinFormat(this.formatIndex);
}
}
}
/*
* (non-Javadoc)
* @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
*/
public void endElement(String uri, String localName, String name)
throws SAXException {
String thisStr = null;
// v => contents of a cell
if ("v".equals(name)) {
// Process the value contents as required.
// Do now, as characters() may be called more than once
switch (nextDataType) {
case BOOL:
char first = value.charAt(0);
thisStr = first == '0' ? "FALSE" : "TRUE";
break;
case ERROR:
thisStr = "\"ERROR:" + value.toString() + '"';
break;
case FORMULA:
// A formula could result in a string value,
// so always add double-quote characters.
thisStr = '"' + value.toString() + '"';
break;
case INLINESTR:
// TODO: have seen an example of this, so it's untested.
XSSFRichTextString rtsi = new XSSFRichTextString(value.toString());
thisStr = '"' + rtsi.toString() + '"';
break;
case SSTINDEX:
String sstIndex = value.toString();
try {
int idx = Integer.parseInt(sstIndex);
XSSFRichTextString rtss = new XSSFRichTextString(sharedStringsTable.getEntryAt(idx));
thisStr = '"' + rtss.toString() + '"';
}
catch (NumberFormatException ex) {
// output.println("Failed to parse SST index '" + sstIndex + "': " + ex.toString());
}
break;
case NUMBER:
String n = value.toString();
if (this.formatString != null)
thisStr = formatter.formatRawCellContents(Double.parseDouble(n), this.formatIndex, this.formatString);
else
thisStr = n;
break;
default:
thisStr = "(TODO: Unexpected type: " + nextDataType + ")";
break;
}
// Output after we've seen the string contents
// Emit commas for any fields that were missing on this row
if (lastColumnNumber == -1) {
lastColumnNumber = 0;
}
for (int i = lastColumnNumber; i <= thisColumn; ++i)
row[thisColumn]=thisStr;
// Update column
if (thisColumn > -1)
lastColumnNumber = thisColumn;
} else if ("row".equals(name)) {
// Print out any missing commas if needed
if (minColumns > 0) {
// Columns are 0 based
if (lastColumnNumber == -1) {
lastColumnNumber = 0;
}
for (int i = lastColumnNumber; i < (this.minColumnCount); i++) {
// output.print(',');
this.data.add(row);
this.row=new String[this.minColumnCount];
if(this.isFirstRow){
this.action.dealList(data,0);
/**
* 需要自己定义的一个异常来中断读取
*/
throw new CommonException("", "已取出第一行,中断线程");
}else{
if(this.data.size()==this.dealSize){
/**
* 用线程来执行
*/
fixedThreadPool.execute(new dealActionThread(this.data,this.beginSize, action));
this.beginSize+=this.data.size();
this.data=new ArrayList<String[]>();
}
}
}
}
// We're onto a new row
// output.println();
lastColumnNumber = -1;
}
}
@Override
public void endDocument() throws SAXException {
super.endDocument();
this.action.dealList(data,this.beginSize);
fixedThreadPool.shutdown();
try {
fixedThreadPool.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* Captures characters only if a suitable element is open.
* Originally was just "v"; extended for inlineStr also.
*/
public void characters(char[] ch, int start, int length)
throws SAXException {
if (vIsOpen)
value.append(ch, start, length);
}
/**
* Converts an Excel column name like "C" to a zero-based index.
*
* @param name
* @return Index corresponding to the specified name
*/
private int nameToColumn(String name) {
int column = -1;
for (int i = 0; i < name.length(); ++i) {
int c = name.charAt(i);
column = (column + 1) * 26 + c - 'A';
}
return column;
}
}
class dealActionThread implements Runnable{
private List<String[]> dealList;
private ExcelDealAction action;
private int beginSize;
public dealActionThread(List<String[]> dealList,int beginSize,ExcelDealAction action){
this.dealList=dealList;
this.action=action;
this.beginSize=beginSize;
}
@Override
public void run() {
this.action.dealList(this.dealList,beginSize);
}
}
///////////////////////////////////////
private OPCPackage xlsxPackage;
private int minColumns;
private ExcelDealAction action;
private int dealSize;
private boolean isFirst;
/**
* Creates a new XLSX -> CSV converter
*
* @param pkg The XLSX package to process
* @param output The PrintStream to output the CSV to
* @param minColumns The minimum number of columns to output, or -1 for no minimum
*/
public CopyOfXLSX2CSV(OPCPackage pkg, ExcelDealAction action, int minColumns,int dealSize,boolean isFirst) {
this.xlsxPackage = pkg;
this.action = action;
this.minColumns = minColumns;
this.dealSize=dealSize;
this.isFirst=isFirst;
}
/**
* Parses and shows the content of one sheet
* using the specified styles and shared-strings tables.
*
* @param styles
* @param strings
* @param sheetInputStream
*/
public void processSheet(
StylesTable styles,
ReadOnlySharedStringsTable strings,
InputStream sheetInputStream)
throws IOException, ParserConfigurationException, SAXException {
InputSource sheetSource = new InputSource(sheetInputStream);
SAXParserFactory saxFactory = SAXParserFactory.newInstance();
SAXParser saxParser = saxFactory.newSAXParser();
XMLReader sheetParser = saxParser.getXMLReader();
ContentHandler handler = new MyXSSFSheetHandler(styles, strings, this.minColumns, this.action,this.dealSize,this.isFirst);
sheetParser.setContentHandler(handler);
sheetParser.parse(sheetSource);
}
/**
* Initiates the processing of the XLS workbook file to CSV.
*
* @throws IOException
* @throws OpenXML4JException
* @throws ParserConfigurationException
* @throws SAXException
*/
public void process()
throws IOException, OpenXML4JException, ParserConfigurationException, SAXException {
ReadOnlySharedStringsTable strings = new ReadOnlySharedStringsTable(this.xlsxPackage);
XSSFReader xssfReader = new XSSFReader(this.xlsxPackage);
StylesTable styles = xssfReader.getStylesTable();
XSSFReader.SheetIterator iter = (XSSFReader.SheetIterator) xssfReader.getSheetsData();
while (iter.hasNext()) {
InputStream stream = iter.next();
String sheetName = iter.getSheetName();
logger.info("处理表单:",sheetName);
processSheet(styles, strings, stream);
stream.close();
}
}
public static void main(String[] args) throws Exception {
File xlsxFile = new File("d:/at2.xlsx");
//列数
int minColumns = 14;
//一次处理的数量
int dealSize=1000;
long begin =System.currentTimeMillis();
OPCPackage p = OPCPackage.open(xlsxFile.getPath(), PackageAccess.READ);
CopyOfXLSX2CSV xlsx2csv = new CopyOfXLSX2CSV(p, new ExcelDealAction() {
@Override
public void dealList(List<String[]> data,int beginSize) {
System.out.println("***********"+":"+data.size());
for(int i=0;i<data.size();i++){
System.out.println(data.get(i)[4]);
}
}
}, minColumns,dealSize,false);//最后一个参数是是否只读取第一行，为了读取字段名行加的
xlsx2csv.process();
System.out.println("耗时:"+(System.currentTimeMillis()-begin));
}
}