Java实现excel大数据量导入

情景分析：

• 通常我们通过poi读取excel文件时，若在用户模式下，由于数据量较大、Sheet较多，很容易出现内存溢出的情况

       用户模式读取excel的典型代码如下：

       FileInputStream file = new FileInputStream("c:\\test.xlsx");

       Workbook wb=new XSSFWorkbook(file);

• 而03版（xls）excel文件每个sheet最大长度为 65536行，07版（xlsx）excel文件每个sheet最大长度为 1048576行，

       因此我们主要解决07版（xlsx）excel大数据量导入出现内存溢出的问题

• 由于读取cvs文件效率高且占用内存少，所以我们采用xlsx转换为cvs的方式来解决

实现代码：

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.apache.poi.hssf.usermodel.HSSFDateUtil;
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.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

public class XLSX2CSV {

	enum xssfDataType {
		BOOL, ERROR, FORMULA, INLINESTR, SSTINDEX, NUMBER,
	}

	/**
	 * 使用xssf_sax_API处理Excel,请参考： http://poi.apache.org/spreadsheet/how-to.html#xssf_sax_api
	 */
	class MyXSSFSheetHandler extends DefaultHandler {

		private StylesTable stylesTable;

		private ReadOnlySharedStringsTable sharedStringsTable;

		private final PrintStream output;

		private final int minColumnCount;

		private boolean vIsOpen;

		private xssfDataType nextDataType;

		private short formatIndex;
		private String formatString;
		private final DataFormatter formatter;

		private int thisColumn = -1;
		private int lastColumnNumber = -1;

		private StringBuffer value;
		private String[] record;
		private List<String[]> rows = new ArrayList<String[]>();
		private boolean isCellNull = false;

		public MyXSSFSheetHandler(StylesTable styles,ReadOnlySharedStringsTable strings, int cols, PrintStream target) {
			this.stylesTable = styles;
			this.sharedStringsTable = strings;
			this.minColumnCount = cols;
			this.output = target;
			this.value = new StringBuffer();
			this.nextDataType = xssfDataType.NUMBER;
			this.formatter = new DataFormatter();
			record = new String[this.minColumnCount];
			rows.clear();// 每次读取都清空行集合
		}

		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);
				}
			}

		}

		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();
					// 判断是否是日期格式
					if (HSSFDateUtil.isADateFormat(this.formatIndex, n)) {
						Double d = Double.parseDouble(n);
						Date date=HSSFDateUtil.getJavaDate(d);
						thisStr=formateDateToString(date);
					} else 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;
				}
				//判断单元格的值是否为空
				if (thisStr == null || "".equals(isCellNull)) {
					isCellNull = true;// 设置单元格是否为空值
				}
				record[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;
					}
					if (isCellNull == false && record[0] != null
							&& record[1] != null)// 判断是否空行
					{
						rows.add(record.clone());
						isCellNull = false;
						for (int i = 0; i < record.length; i++) {
							record[i] = null;
						}
					}
				}
				lastColumnNumber = -1;
			}

		}

		public List<String[]> getRows() {
			return rows;
		}

		public void setRows(List<String[]> rows) {
			this.rows = rows;
		}

		/**
		 * 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;
		}

		private String formateDateToString(Date date) {
			SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//格式化日期
			return sdf.format(date);

		}

	}

	private OPCPackage xlsxPackage;
	private int minColumns;
	private PrintStream output;

	/**
	 * 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 XLSX2CSV(OPCPackage pkg, PrintStream output,int minColumns) {
		this.xlsxPackage = pkg;
		this.output = output;
		this.minColumns = minColumns;
	}

	/**
	 * Parses and shows the content of one sheet using the specified styles and
	 * shared-strings tables.
	 * @param styles
	 * @param strings
	 * @param sheetInputStream
	 */
	public List<String[]> 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();
		MyXSSFSheetHandler handler = new MyXSSFSheetHandler(styles, strings,this.minColumns, this.output);
		sheetParser.setContentHandler(handler);
		sheetParser.parse(sheetSource);
		return handler.getRows();
	}

	/**
	 * 初始化这个处理程序 
	 * @throws IOException
	 * @throws OpenXML4JException
	 * @throws ParserConfigurationException
	 * @throws SAXException
	 */
	public List<String[]> process() throws IOException, OpenXML4JException,ParserConfigurationException, SAXException {
		ReadOnlySharedStringsTable strings = new ReadOnlySharedStringsTable(this.xlsxPackage);
		XSSFReader xssfReader = new XSSFReader(this.xlsxPackage);
		List<String[]> list = null;
		StylesTable styles = xssfReader.getStylesTable();
		XSSFReader.SheetIterator iter = (XSSFReader.SheetIterator) xssfReader.getSheetsData();
		int index = 0;
		while (iter.hasNext()) {
			InputStream stream = iter.next();
			index++;
			//默认取第一个工作薄
			if(index == 1){
				list = processSheet(styles, strings, stream);
				stream.close();
			}
		}
		return list;
	}

	/**
	 * 读取Excel
	 * 
	 * @param path
	 *            文件路径
	 * @param sheetName
	 *            sheet名称
	 * @param minColumns
	 *            列总数
	 * @return
	 * @throws SAXException
	 * @throws ParserConfigurationException
	 * @throws OpenXML4JException
	 * @throws IOException
	 */
	private static List<String[]> readerExcel(String path,int minColumns) throws IOException, OpenXML4JException,ParserConfigurationException, SAXException {
		OPCPackage p = OPCPackage.open(path, PackageAccess.READ);
		XLSX2CSV xlsx2csv = new XLSX2CSV(p, System.out, minColumns);
		List<String[]> list = xlsx2csv.process();
		p.close();
		return list;
	}
	
	/**
	 * 读取Excel
	 * 
	 * @param file
	 *            File
	 * @param sheetName
	 *            sheet名称
	 * @param minColumns
	 *            列总数
	 * @return
	 * @throws SAXException
	 * @throws ParserConfigurationException
	 * @throws OpenXML4JException
	 * @throws IOException
	 */
	private static List<String[]> readerExcelInputStream(File file,int minColumns) throws IOException, OpenXML4JException, ParserConfigurationException, SAXException {
		OPCPackage p = OPCPackage.openOrCreate(file);
		XLSX2CSV xlsx2csv = new XLSX2CSV(p, System.out, minColumns);
		List<String[]> list = xlsx2csv.process();
		p.close();
		return list;
	}
		
	//获取表头及数据内容,可在业务层调用
	public static Map<String,Object> getTableDate(InputStream in) throws IOException, OpenXML4JException, ParserConfigurationException, SAXException{		
		File out = new File("C:\\date.xlsx");//默认在C盘生成date.xlsx文件
		OutputStream output = null;
		try {
			output = new FileOutputStream(out);
			byte[] buf = new byte[1024];
			int bytesRead;
			while ((bytesRead = in.read(buf)) > 0) {
				output.write(buf, 0, bytesRead);
			}
		} finally {
			in.close();
			output.close();
		}
		Map<String,Object> map = new HashMap<String,Object>();
		List<String> headresult = new ArrayList<String>();//表头集合
		List<List<String>> dataresult = new ArrayList<List<String>>();//表数据集合
		List<String[]> list = readerExcelInputStream(out,30);//默认读取30列
		for(int i=0;i<list.size();i++){
			if(i == 0){
				for(String cell : list.get(i)){
					if(cell != null){					
						headresult.add(cell);
					}
				}
			}else{
				List<String> dataList = new ArrayList<String>();
				for(String cell : list.get(i)){
					dataList.add(cell == null ? "" : cell);
				}
				dataresult.add(dataList);
			}
		}
		map.put("headresult", headresult);
		map.put("dataresult", dataresult);
		return map;
	}

	public static void main(String[] args) throws Exception {
		File file = new File("C:/Users/Administrator/Desktop/测试.xlsx");
		System.out.println("开始读取...");
		List<String[]> list = XLSX2CSV.readerExcelInputStream(file, 30);//默认读取30列
		System.out.println("数据量："+list.size());
		for(int i=0;i<list.size();i++){
			if(i > 0){
				for (String cell : list.get(i)) {
					System.out.print(cell + ",");
				}
				System.out.println();
			}
		}
	}

}

说明：

       代码中的加载excel的核心方法：

       OPCPackage pkg = OPCPackage.open(path);//文件路径

• OPCPackage pkg = OPCPackage.openOrCreate(file);//文件

• OPCPackage pkg = OPCPackage.open(InputStream);//文件流

• 文件流方式对内存依赖极大，所以实际应用时，如果只能获取文件流的话，可以先将文件通过流拷贝到本地再解析