biz.ganttproject.impex.csv.XlsReaderImpl.java Source code

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Here is the source code for biz.ganttproject.impex.csv.XlsReaderImpl.java

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/*
Copyright 2017 Roman Torkhov, BarD Software s.r.o
    
This file is part of GanttProject, an opensource project management tool.
    
GanttProject is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.
    
GanttProject is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
    
You should have received a copy of the GNU General Public License
along with GanttProject.  If not, see <http://www.gnu.org/licenses/>.
*/
package biz.ganttproject.impex.csv;

import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Workbook;

import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * @author torkhov
 */
class XlsReaderImpl implements SpreadsheetReader {

    private final Workbook myBook;
    private final Map<String, Integer> myHeaders;

    XlsReaderImpl(InputStream is, List<String> columnHeaders) throws IOException {
        myBook = new HSSFWorkbook(is);
        myHeaders = initializeHeader(columnHeaders);
    }

    @Override
    public void close() throws IOException {
        myBook.close();
    }

    @Override
    public Iterator<SpreadsheetRecord> iterator() {
        return Iterators.transform(myBook.getSheetAt(0).iterator(),
                (input) -> new XlsRecordImpl(getCellValues(input), myHeaders));
    }

    private List<String> getCellValues(Row row) {
        return Lists.newArrayList(Iterables.transform(row, Cell::getStringCellValue));
    }

    /**
     * This method was taken from {@link org.apache.commons.csv.CSVParser#initializeHeader}
     * Create the name to index mapping if the column headers not {@code null}.
     * @param columnHeaders column headers
     * @return the name to index mapping
     */
    private Map<String, Integer> initializeHeader(List<String> columnHeaders) {
        Map<String, Integer> hdrMap = null;
        List<String> formatHeader = columnHeaders;
        if (formatHeader != null) {
            hdrMap = new LinkedHashMap<>();
            List<String> headerRecord = null;
            if (formatHeader.isEmpty()) {
                // read the header from the first line of the file
                Row row = myBook.getSheetAt(0).getRow(0);
                if (row != null) {
                    headerRecord = getCellValues(row);
                }
            } else {
                headerRecord = formatHeader;
            }

            // build the name to index mappings
            if (headerRecord != null) {
                for (int i = 0; i < headerRecord.size(); i++) {
                    String header = headerRecord.get(i);
                    if (hdrMap.containsKey(header)) {
                        throw new IllegalArgumentException(
                                "The header contains a duplicate name: \"" + header + "\" in " + headerRecord);
                    }
                    hdrMap.put(header, i);
                }
            }
        }
        return hdrMap;
    }
}