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   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */
        
package org.apache.poi.hssf.usermodel.examples;

import org.apache.poi.hssf.eventusermodel.HSSFEventFactory;
import org.apache.poi.hssf.eventusermodel.HSSFListener;
import org.apache.poi.hssf.eventusermodel.HSSFRequest;
import org.apache.poi.hssf.record.*;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * This example shows how to use the event API for reading a file.
 */
public class EventExample implements HSSFListener {
    private SSTRecord sstrec;

    /**
     * This method listens for incoming records and handles them as required.
     * @param record    The record that was found while reading.
     */
    @Override
    public void processRecord(Record record)
    {
        switch (record.getSid())
        {
            // the BOFRecord can represent either the beginning of a sheet or the workbook
            case BOFRecord.sid:
                BOFRecord bof = (BOFRecord) record;
                if (bof.getType() == BOFRecord.TYPE_WORKBOOK)
                {
                    System.out.println("Encountered workbook");
                    // assigned to the class level member
                } else if (bof.getType() == BOFRecord.TYPE_WORKSHEET)
                {
                    System.out.println("Encountered sheet reference");
                }
                break;
            case BoundSheetRecord.sid:
                BoundSheetRecord bsr = (BoundSheetRecord) record;
                System.out.println("New sheet named: " + bsr.getSheetname());
                break;
            case RowRecord.sid:
                RowRecord rowrec = (RowRecord) record;
                System.out.println("Row found, first column at "
                        + rowrec.getFirstCol() + " last column at " + rowrec.getLastCol());
                break;
            case NumberRecord.sid:
                NumberRecord numrec = (NumberRecord) record;
                System.out.println("Cell found with value " + numrec.getValue()
                        + " at row " + numrec.getRow() + " and column " + numrec.getColumn());
                break;
                // SSTRecords store a array of unique strings used in Excel.
            case SSTRecord.sid:
                sstrec = (SSTRecord) record;
                for (int k = 0; k < sstrec.getNumUniqueStrings(); k++)
                {
                    System.out.println("String table value " + k + " = " + sstrec.getString(k));
                }
                break;
            case LabelSSTRecord.sid:
                LabelSSTRecord lrec = (LabelSSTRecord) record;
                System.out.println("String cell found with value "
                        + sstrec.getString(lrec.getSSTIndex()));
                break;
        }
    }

    /**
     * Read an excel file and spit out what we find.
     *
     * @param args      Expect one argument that is the file to read.
     * @throws IOException  When there is an error processing the file.
     */
    public static void main(String[] args) throws IOException
    {
        // create a new file input stream with the input file specified
        // at the command line
        try (FileInputStream fin = new FileInputStream(args[0])) {
            // create a new org.apache.poi.poifs.filesystem.Filesystem
            try (POIFSFileSystem poifs = new POIFSFileSystem(fin)) {
                // get the Workbook (excel part) stream in a InputStream
                try (InputStream din = poifs.createDocumentInputStream("Workbook")) {
                    // construct out HSSFRequest object
                    HSSFRequest req = new HSSFRequest();
                    // lazy listen for ALL records with the listener shown above
                    req.addListenerForAllRecords(new EventExample());
                    // create our event factory
                    HSSFEventFactory factory = new HSSFEventFactory();
                    // process our events based on the document input stream
                    factory.processEvents(req, din);
                }
            }
        }
        System.out.println("done.");
    }
}
