Reading large excel files

By using this we can read excel sheets having large size

package com.excel.reader;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

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

import org.apache.poi.hssf.record.BOFRecord;
import org.apache.poi.hssf.record.BoundSheetRecord;
import org.apache.poi.hssf.record.LabelSSTRecord;
import org.apache.poi.hssf.record.NumberRecord;
import org.apache.poi.hssf.record.Record;
import org.apache.poi.hssf.record.RowRecord;
import org.apache.poi.hssf.record.SSTRecord;
import org.apache.poi.hssf.eventusermodel.HSSFListener;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.openxml4j.exceptions.InvalidOperationException;
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;

import com.excel.reader.config.ProcessSheetInterface;

public class ReadExcelFile {

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

    int countrows = 0;
    private ProcessSheetInterface handlerInterface;
    class XSSFSheetHandler extends DefaultHandler {

        /**
         * Table with styles
         */
        private StylesTable stylesTable;

        /**
         * Table with unique strings
         */
        private ReadOnlySharedStringsTable sharedStringsTable;

        /**
         * Destination for data
         */
        private final PrintStream output;

        private List<?> list = new ArrayList();

        private Class clazz;

        /**
         * Number of columns to read starting with leftmost
         */
        private final int minColumnCount;
        private int count=0;
        String[] strValues = new String[3];

        // 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;

        /**
         * 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 XSSFSheetHandler(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();
        }

        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();
                    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)
                    output.print(',');*/

                // Might be the empty string.
               handlerInterface.processEachRecord(thisColumn,countrows,thisStr);
                /*if(thisColumn == 1 || thisColumn ==0 || thisColumn==2)
                        strValues[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(',');
                    }*/
                }


               handlerInterface.rowCompleted();
                // We're onto a new row
               /* if(strValues[1].equals("Y"))
                 {                   
                  output.println("found : "+strValues[0]+"       "+strValues[2]);
                  count++;
                  }*/
                     countrows++;
                lastColumnNumber = -1;

            }

        }

        /**
         * 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 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
     */
    private ReadExcelFile(OPCPackage pkg, PrintStream output, int minColumns,ProcessSheetInterface handlerInterface,int sheetNo) {
        this.xlsxPackage = pkg;
        this.output = output;
        this.minColumns = minColumns;
        this.handlerInterface = handlerInterface;
        try
        {
         process(sheetNo);
        }catch(Exception ex)
        {
         output.println(ex);
        }
    }

    /**
     * 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 XSSFSheetHandler(styles, strings,
                this.minColumns, this.output);
        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(int sheetNo) 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();
        int index = 0;
        while (iter.hasNext()) {
            InputStream stream = iter.next();
            if(index==sheetNo)
            {
           // String sheetName = iter.getSheetName();
            processSheet(styles, strings, stream);
            }
            stream.close();
            ++index;
        }
    }
    public static void ProcessExcelSheet(String filePath,int sheetNo,ProcessSheetInterface handlerObject,PrintStream output,int maxColoumnCount) throws IOException, OpenXML4JException, ParserConfigurationException, SAXException
    {
     Class clazz = ReadExcelFile.class;
     PrintStream out;
     if(output!=null)
      out = output;
     else
      out= System.out;
     try
     {
     OPCPackage excelPackage = OPCPackage.open(filePath);
     new ReadExcelFile(excelPackage,System.out,maxColoumnCount,handlerObject,sheetNo);
     }
     catch(InvalidOperationException exe)
     {
      org.apache.poi.openxml4j.opc.Package pkg = org.apache.poi.openxml4j.opc.Package.open(filePath);
     // new ReadExcelXlsFile(pkg,System.out,maxColoumnCount,handlerObject,sheetNo);
          
     }
     
          
          
     
     }

 
}



package com.excel.reader.config;

public interface ProcessSheetInterface {
 public void processEachRecord(int row,int coloumn,String value);
 public void rowCompleted();
}