Java web

java poi excel转csv

2019-01-07  本文已影响0人  haiyong6

在上传excel功能中,对于很大的excel文件直接上传往往会因为文件太大导致内存溢出上传失败,poi提供了首先把excel转为csv再读取上传的方法,在此记录一下。
所需jar包 maven pom.xml配置:

    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>4.1.0</version>
    </dependency>
    
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>4.1.0</version>
    </dependency>

新建XLSXCovertCSVReader工具类

package com.ways.app.framework.base;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

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;

/**
 * 使用CVS模式解决XLSX文件,可以有效解决用户模式内存溢出的问题
 */
public class XLSXCovertCSVReader {

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

    class MyXSSFSheetHandler extends DefaultHandler {
        
        private int isNotNullIndex;
        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
                ,int isNotNullIndex) {
            this.isNotNullIndex = isNotNullIndex;
            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:
                        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;       //添加
                // 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[isNotNullIndex] != null)// 判断是否空行
                    {
                        rows.add(record.clone());       //添加
                        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;
        }

        public void characters(char[] ch, int start, int length) throws SAXException {
            if (vIsOpen)
                value.append(ch, start, length);
        }

        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;
    private String sheetName;
    private int isNotNullIndex;

    public XLSXCovertCSVReader(OPCPackage pkg, PrintStream output,
            String sheetName, int minColumns,int isNotNullIndex) {
        this.isNotNullIndex = isNotNullIndex;
        this.xlsxPackage = pkg;
        this.output = output;
        this.minColumns = minColumns;
        this.sheetName = sheetName;
    }

    public List<String[]> processSheet(StylesTable styles,
            ReadOnlySharedStringsTable strings, InputStream sheetInputStream,int isNotNullIndex)
            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,isNotNullIndex);   //内部类
        sheetParser.setContentHandler(handler);
        sheetParser.parse(sheetSource);
        return handler.getRows();
    }

    /**
     * 初始化这个处理程序 将
     * @throws IOException
     * @throws OpenXML4JException
     * @throws ParserConfigurationException
     * @throws SAXException
     */
    public List<String[]> process(int isNotNullIndex) 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();
            String sheetNameTemp = iter.getSheetName();
            if (this.sheetName.equals(sheetNameTemp)) {
                list = processSheet(styles, strings, stream,isNotNullIndex);
                stream.close();
                ++index;
            }
        }
        return list;
    }

    /**
     * 读取Excel
     * @param path 文件路径
     * @param sheetName sheet名称
     * @param minColumns 列总数(最后一列的下标)
     * @param isNotNullIndex 判断那一列数据不为空(此列不为空,则整行数据有效)
     * @return
     * @throws SAXException
     * @throws ParserConfigurationException
     * @throws OpenXML4JException
     * @throws IOException
     */
    public static List<String[]> readerExcel(String path, String sheetName,int minColumns,int isNotNullIndex) throws IOException, OpenXML4JException,
            ParserConfigurationException, SAXException {
        OPCPackage pkg = OPCPackage.open(path, PackageAccess.READ);
        XLSXCovertCSVReader xlsx2csv = new XLSXCovertCSVReader(pkg, System.out,sheetName, minColumns,isNotNullIndex);
        List<String[]> list = xlsx2csv.process(isNotNullIndex);
        pkg.close();
        return list;
    }

//  public static void main(String[] args) throws Exception {
//      try {
//          List<String[]> list = XLSXCovertCSVReader.readerExcel("C:/Users/hujianrong/Desktop/20170522/testddd.xlsx","报表", 13,1);
//          for (String[] record : list) {
//              for (String cell : record) {
//                  System.out.print(cell + "  ");
//              }
//              System.out.println();
//          }
//      } catch (Exception e) {
//          e.printStackTrace();
//      }
//  }

}

按上面代码新建XLSXCovertCSVReader 这个实体类,其中,readerExcel这个方法就可以直接在程序中调用了,参数分别为 文件路径,读取excel的sheet名称,固定列总数,不为空列的index,一般是1, 1代表整行数据有效,到最大列的中间列都不允许有空值。返回的list即是最终结果,可遍历循环插入数据库。

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