spring batch itemWriter for pdf

Question

Is there any method to write data to a PDF file using spring batch ItemWriter. I saw a lot of examples for .txt, .xml etc. None for pdf writer. Using spring boot with batch. Thanks in advance.

Answer 1

There is not an out of the box ItemWriter for generating PDF Documents. However, implementing your own should be straight forward with various open source libraries.

Answer 2

You don't need a ItemWriter to write data to PDF. What you can do is using a processor in between the writer and reader. There are existing API libraries for you to convert DB, XML or JSON into PDF. Here is an example from Tutorials Point, which I found successful in my program to read an XML to DB and, meanwhile create a PDF file.

import java.io.File;
import java.io.IOException;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.font.PDType1Font;
import org.springframework.batch.item.ItemProcessor;

public class CustomItemProcessor implements ItemProcessor<Tutorial, Tutorial> {

public static void drawTable(PDPage page, PDPageContentStream contentStream, float y, float margin,
        String[][] content) throws IOException {
    final int rows = content.length;
    final int cols = content[0].length;
    final float rowHeight = 50;
    final float tableWidth = page.getMediaBox().getWidth() - (2 * margin);
    final float tableHeight = rowHeight * rows;
    final float colWidth = tableWidth / (float) cols;
    final float cellMargin = 5f;

    // draw the rows
    float nexty = y;
    for (int i = 0; i <= rows; i++) {
        contentStream.drawLine(margin, nexty, margin + tableWidth, nexty);
        nexty -= rowHeight;
    }

    // draw the columns
    float nextx = margin;
    for (int i = 0; i <= cols; i++) {
        contentStream.drawLine(nextx, y, nextx, y - tableHeight);
        nextx += colWidth;
    }

    // now add the text
    contentStream.setFont(PDType1Font.HELVETICA_BOLD, 12);

    float textx = margin + cellMargin;
    float texty = y - 15;
    for (int i = 0; i < content.length; i++) {
        for (int j = 0; j < content[i].length; j++) {
            String text = content[i][j];
            contentStream.beginText();
            contentStream.moveTextPositionByAmount(textx, texty);
            contentStream.drawString(text);
            contentStream.endText();
            textx += colWidth;
        }

        texty -= rowHeight;
        textx = margin + cellMargin;
    }
}

@Override
public Tutorial process(Tutorial item) throws Exception {
    System.out.println("Processing..." + item);

    // Creating PDF document object
    File f = new File("/Users/zhenxu/Desktop/test.pdf");
    PDDocument doc = PDDocument.load(f);

    // Creating a blank page
    PDPage page = new PDPage();
    doc.addPage(page);
    PDPageContentStream contentStream = new PDPageContentStream(doc, page);

    String[][] content = { { "Id", "" + item.getTutorial_id() }, { "Title", item.getTutorial_title() },
            { "Authour", item.getTutorial_author() }, { "Submission Date", item.getSubmission_date() } };
    drawTable(page, contentStream, 700, 100, content);

    contentStream.close();
    doc.save("/Users/zhenxu/Desktop/test.pdf");
    System.out.println("Hello");
    return item;
}

Here the input item is the input XML. The job config goes like:

    <!-- Defining a job--> 
<batch:job id = "helloWorldJob">  
    <!-- Defining a Step --> 
    <batch:step id = "step1"> 
        <batch:tasklet>
            <!-- try use PDF converter -->
            <batch:chunk reader="xmlItemReader" writer="mySqlItemWriter" processor="itemProcessor" commit-interval="10"></batch:chunk>                
        </batch:tasklet>    
    </batch:step>  
</batch:job> 

You can customize your reader and writer as well to do other kinds of jobs.