SpringBoot 文档处理转换：PDF、Word、Excel、图片互转

在 Spring Boot 中，可以使用一些现有的 Java 库来处理和转换文档、图片和 PDF 文件。以下是一些常用的库和示例代码：

PDF 转 Word：
- 使用 Apache PDFBox 库来提取 PDF 中的文本内容，然后使用 Apache POI 库将文本内容保存为 Word 文件。

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.text.PDFTextStripper;
import org.apache.poi.xwpf.usermodel.XWPFDocument;
import org.apache.poi.xwpf.usermodel.XWPFParagraph;
import org.apache.poi.xwpf.usermodel.XWPFRun;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class PdfToWordConverter {

    public static void convert(String pdfFilePath, String wordFilePath) throws IOException {
        PDDocument document = PDDocument.load(new File(pdfFilePath));
        PDFTextStripper stripper = new PDFTextStripper();

        XWPFDocument wordDocument = new XWPFDocument();
        XWPFParagraph paragraph = wordDocument.createParagraph();
        XWPFRun run = paragraph.createRun();

        run.setText(stripper.getText(document));

        FileOutputStream out = new FileOutputStream(wordFilePath);
        wordDocument.write(out);
        out.close();

        document.close();
        wordDocument.close();

        System.out.println('PDF 转 Word 成功！');
    }
}

图片转 Word：
- 使用 Apache POI 库来创建一个 Word 文档，并将图片插入到文档中。

import org.apache.poi.xwpf.usermodel.XWPFDocument;
import org.apache.poi.xwpf.usermodel.XWPFRun;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class ImageToWordConverter {

    public static void convert(String imageFilePath, String wordFilePath) throws IOException {
        XWPFDocument wordDocument = new XWPFDocument();
        XWPFRun run = wordDocument.createParagraph().createRun();

        FileInputStream imageInputStream = new FileInputStream(imageFilePath);
        BufferedImage image = ImageIO.read(imageInputStream);
        imageInputStream.close();

        FileOutputStream out = new FileOutputStream(wordFilePath);
        ImageIO.write(image, 'png', out);
        out.close();

        wordDocument.close();

        System.out.println('图片转 Word 成功！');
    }
}

PDF 转 Excel：
- 使用 Apache PDFBox 库来提取 PDF 中的表格数据，然后使用 Apache POI 库将表格数据保存为 Excel 文件。

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.text.PDFTextStripper;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class PdfToExcelConverter {

    public static void convert(String pdfFilePath, String excelFilePath) throws IOException {
        PDDocument document = PDDocument.load(new File(pdfFilePath));
        PDFTextStripper stripper = new PDFTextStripper();

        Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet();

        int rowIndex = 0;
        for (PDPage page : document.getPages()) {
            stripper.setStartPage(document.getDocumentCatalog().getPages().indexOf(page) + 1);
            stripper.setEndPage(document.getDocumentCatalog().getPages().indexOf(page) + 1);

            String text = stripper.getText(document);
            String[] lines = text.split('\r?\n');

            for (int i = 0; i < lines.length; i++) {
                Row row = sheet.createRow(rowIndex++);
                String[] cells = lines[i].split('\t');
                for (int j = 0; j < cells.length; j++) {
                    Cell cell = row.createCell(j);
                    cell.setCellValue(cells[j]);
                }
            }
        }

        FileOutputStream out = new FileOutputStream(excelFilePath);
        workbook.write(out);
        out.close();

        document.close();
        workbook.close();

        System.out.println('PDF 转 Excel 成功！');
    }
}

图片转 Excel：
- 使用 Apache POI 库创建一个 Excel 文件，并将图片插入到 Excel 文件的单元格中。

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

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class ImageToExcelConverter {

    public static void convert(String imageFilePath, String excelFilePath) throws IOException {
        Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet();
        Drawing drawing = sheet.createDrawingPatriarch();
        CreationHelper helper = workbook.getCreationHelper();

        BufferedImage image = ImageIO.read(new File(imageFilePath));
        int pictureIdx = workbook.addPicture(ImageIO.read(new FileInputStream(imageFilePath)), Workbook.PICTURE_TYPE_PNG);

        ClientAnchor anchor = helper.createClientAnchor();
        anchor.setCol1(0);
        anchor.setRow1(0);

        Picture picture = drawing.createPicture(anchor, pictureIdx);
        picture.resize();

        FileOutputStream out = new FileOutputStream(excelFilePath);
        workbook.write(out);
        out.close();

        workbook.close();

        System.out.println('图片转 Excel 成功！');
    }
}

PDF 转图片：
- 使用 Apache PDFBox 库将 PDF 转换为一系列图片文件。

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.PDFRenderer;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class PdfToImageConverter {

    public static void convert(String pdfFilePath, String imageFilePath) throws IOException {
        PDDocument document = PDDocument.load(new File(pdfFilePath));
        PDFRenderer renderer = new PDFRenderer(document);

        for (int i = 0; i < document.getNumberOfPages(); i++) {
            BufferedImage image = renderer.renderImage(i);
            ImageIO.write(image, 'png', new File(imageFilePath + '_' + (i + 1) + '.png'));
        }

        document.close();

        System.out.println('PDF 转图片成功！');
    }
}

图片转 PDF：
- 使用 Apache PDFBox 库将图片转换为 PDF 文件。

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.PDPageContentStream.AppendMode;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class ImageToPdfConverter {

    public static void convert(String imageFilePath, String pdfFilePath) throws IOException {
        PDDocument document = new PDDocument();
        BufferedImage image = ImageIO.read(new File(imageFilePath));

        PDPage page = new PDPage();
        document.addPage(page);

        PDImageXObject ximage = PDImageXObject.createFromFile(imageFilePath, document);
        PDPageContentStream contentStream = new PDPageContentStream(document, page, AppendMode.APPEND, true, true);

        contentStream.drawImage(ximage, 0, 0, page.getMediaBox().getWidth(), page.getMediaBox().getHeight());
        contentStream.close();

        document.save(pdfFilePath);
        document.close();

        System.out.println('图片转 PDF 成功！');
    }
}

请注意，以上示例代码仅提供了基本的实现思路和方法，您可能需要根据实际需求进行适当的修改和优化。另外，这些示例代码需要相应的依赖库，请确保在项目中添加了这些库的依赖。