spring batch itemWriter for pdf

Question

有没有什么方法可以使用spring batch ItemWriter将数据写入PDF文件。我看过很多.txt，.xml等的例子，没有一个是给pdf writer的。使用spring boot和batch。提前谢谢。

Answer 1

没有用于生成PDF文档的开箱即用ItemWriter。但是，使用各种开源库实现自己的库应该很简单。

Answer 2

你不需要一个ItemWriter来写数据到PDF。你能做的就是在写入器和读取器之间使用一个处理器。现有的API库可用于将DB、XML或JSON转换为PDF。下面是一个来自Tutorials Point的示例，我发现它在我的程序中成功地将XML读取到DB，同时创建了一个PDF文件。

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;
}

这里的输入item就是输入的XML。作业配置如下：

    <!-- 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> 

你也可以定制你的阅读器和写入器来做其他类型的工作。