如何从同一行显示的Excel文件中显示两个不同大小的数组以输出PDF？

Question

I have an Excel file I'm reading in with Apache POI and getting headers, rows & cell data which I'm storing in two arrays. I am using PDF box and am trying to display all of the headers vertically with the corresponding row data.

For example: the header row contains name, email, date of birth, salary and department followed by three rows of data. Each row of data should produce its own PDF document listing the labels and values vertically down the page but for now I'm only trying to list all the values in one PDF document.

• Name: Joe Smith
• Email: js@something.com
• Date of Birth: 05/06/1976
• Salary: $100,000.00
• Department: Sales

The problem I'm having is only the last record in my Excel sheet is printing to the PDF and the headers are mismatching the corresponding row and cell data. I believe this is due to the mismatch in the count of 5 elements in the header array and 15 elements in the cell array.

Below are some snippets of what I'm doing to produce this along with a screen shot of both my Excel file layout and the PDF that's being generated.

My Excel Sheet (right click to open not sure why it isn't linking to full size pics below)

//Hold header values in Array
List<String> headerValues = new ArrayList<>();

//Hold cell values in Array
List<String> cellValues = new ArrayList<>();

for(int i = 0; i < headerValues.size() && i < cellValues.size(); i++){
    cont.showText(headerValues.get(i) + cellValues.get(i));
    cont.newLine();
}

Here was another way I had done this which produced the same result as the for loop

Iterator<String> h = headerValues.iterator();
Iterator<String> c = cellValues.iterator();

while(h.hasNext() && c.hasNext()){
    cont.showText(h.next() +":" + c.next());
    cont.newLine();
}

The result I'm trying to get to is print each of the header values in my excel spreadsheet vertically for each row's data in my Excel Sheet.

Answer 1

Your collection structure is not optimal. At least your cell values should not be all in one list. The data structure of an default Excel table is like a database table. There are data records (the rows) which consists of fields (the column headers). So your cell values should be in a List<List<String>> dataRecords . There the main List is a list of rows and the inner List is the list of fields in the rows.

The column headers might be a List<String> colHeaders but the better structure would be a TreeMap<Integer, String> colHeaders where the Integer key is the column index in the Excel sheet. Using that it is clear what Excel columns in the sheet really contain the data fields.

Let's have a complete example:

import java.io.FileInputStream;

import org.apache.poi.ss.usermodel.*;

import org.apache.pdfbox.pdmodel.*;
import org.apache.pdfbox.pdmodel.font.*;
import org.apache.pdfbox.pdmodel.common.*;

import java.util.Map;
import java.util.TreeMap;
import java.util.List;
import java.util.ArrayList;

class GetDataFromExcel {

 public static void main(String[] args) throws Exception {

  Workbook workbook = WorkbookFactory.create(new FileInputStream("ExcelExample.xlsx"));

  DataFormatter dataFormatter = new DataFormatter();
  FormulaEvaluator formulaEvaluator = workbook.getCreationHelper().createFormulaEvaluator();

  Sheet sheet = workbook.getSheetAt(0);

  int headerRowNum = sheet.getFirstRowNum();

  // collecting the column headers
  TreeMap<Integer, String> colHeaders = new TreeMap<Integer, String>();
  Row row = sheet.getRow(headerRowNum);
  for (Cell cell : row) {
   int colIdx = cell.getColumnIndex();
   String value = dataFormatter.formatCellValue(cell, formulaEvaluator);
   colHeaders.put(colIdx, value);
  }

System.out.println(colHeaders);

  // collecting the data records
  List<List<String>> dataRecords = new ArrayList<List<String>>();
  for (int r = headerRowNum + 1; r <= sheet.getLastRowNum(); r++) {
   row = sheet.getRow(r); if (row == null) row = sheet.createRow(r);
   List<String> values = new ArrayList<String>();
   for (Map.Entry<Integer, String> entry : colHeaders.entrySet()) {
    int colIdx = entry.getKey();
    Cell cell = row.getCell(colIdx); if (cell == null) cell = row.createCell(colIdx);
    String value = dataFormatter.formatCellValue(cell, formulaEvaluator);
    values.add(value);
   }
   dataRecords.add(values);
  }

System.out.println(dataRecords);

  workbook.close();

  // create PDF
  final PDFont font = PDType1Font.HELVETICA;
  final float fontSize = 12.0f;
  final float lineHeight = fontSize * 1.42857f;
  PDPage page = new PDPage(); //U.S. Letter, 8.5" x 11"
  final PDRectangle artBox = page.getArtBox();
  final float artBoxHeight = artBox.getHeight();
  final float artBoxWidth = artBox.getWidth();
  final float leftMargin = artBoxWidth / 8.5f; // 1"
  final float topMargin = artBoxHeight / 11.0f; // 1"
  final float bottomMargin = artBoxHeight / 11.0f; // 1"

  PDDocument doc = new PDDocument();

  doc.addPage(page);
  PDPageContentStream contents = new PDPageContentStream(doc, page);
  contents.beginText();
  contents.setFont(font, fontSize);
  float currentLinePos = artBoxHeight-topMargin;
  contents.newLineAtOffset(leftMargin, currentLinePos);

  for (List<String> dataRecord : dataRecords) {
   Integer colIdx = colHeaders.firstKey();
   for (String value : dataRecord) {
    if (colIdx != null) {
     String header = colHeaders.get(colIdx);
     if (currentLinePos <= bottomMargin) {
      contents.endText();
      contents.close();
      page = new PDPage();
      doc.addPage(page);
      contents = new PDPageContentStream(doc, page);
      contents.beginText();
      contents.setFont(font, fontSize);
      currentLinePos = artBoxHeight-topMargin;
      contents.newLineAtOffset(leftMargin, currentLinePos);
     }
     contents.showText(header + ": " + value);
     contents.newLineAtOffset(0, -lineHeight);
     currentLinePos -= lineHeight;
    }
    colIdx = colHeaders.higherKey(colIdx);
   }
   contents.newLineAtOffset(0, -lineHeight);
   currentLinePos -= lineHeight;   
  }

  contents.endText();
  contents.close();

  doc.save("ExcelExample.pdf");
  doc.close();

 }
}