文档在线预览（四）将word、txt、ppt、excel、图片转成pdf来实现在线预览

之前在写文档在线预览时留下了一个小坑，当时比较推荐的做法是将各种类型的文档都由后端统一转成pdf格式再由前端进行展示，但是当时并没有提供将各种类型的文档转pdf的方法，这次就来填一下这个坑。
前端在线预览pdf文件的实现方式可以参考这篇文章：《文档在线预览（三）使用js前端实现word、excel、pdf、ppt 在线预览》中 PDF文件实现前端预览 部分。

事前准备

代码基于 aspose-words（用于word、txt转pdf），itextpdf（用于ppt、图片、excel转pdf），所以事先需要在项目里下面以下依赖

1、需要的maven依赖

		    
  	  		com.luhuiguo    
   		 	aspose-words    
  		  	23.1
		
		
		
            org.apache.poi
            poi
            5.2.0
        
        
            org.apache.poi
            poi-ooxml
            5.2.0
        
        
            org.apache.poi
            poi-scratchpad
            5.2.0
        
        
            org.apache.poi
            poi-excelant
            5.2.0
        
        
        
            com.itextpdf
            itextpdf
            5.5.13.2
        
        
            com.itextpdf
            itext-asian
            5.2.0
        		        

2、后面用到的工具类代码：

package com.fhey.service.common.utils.file;

import cn.hutool.core.util.StrUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

/**
 * @author fhey
 * @date 2023-04-20 11:15:58
 * @description: 文件工具类
 */
public class FileUtil {
    private static final Logger logger = LoggerFactory.getLogger(FileUtil.class);

    //获取新文件的全路径
    public static String getNewFileFullPath(String sourceFilePath, String destFilePath, String ext) {
        File destFile = new File(destFilePath);
        if (destFile.isFile()) {
            return destFilePath;
        }
        File sourceFile = new File(sourceFilePath);
        String sourceFileName = sourceFile.getName();
        if (sourceFile.isFile()) {
            return destFilePath + File.separator + sourceFileName.substring(0, sourceFileName.lastIndexOf(StrUtil.DOT)) + StrUtil.DOT + ext;
        }
        return destFilePath + File.separator + sourceFileName + StrUtil.DOT + ext;
    }

    //判断文件是否是图片
    public static boolean isImage(File file) throws IOException {
        FileInputStream is = new FileInputStream(file);
        byte[] bytes = new byte[8];
        is.read(bytes);
        is.close();
        String type = bytesToHexString(bytes).toUpperCase();
        if (type.contains("FFD8FF") //JPEG(jpg)
                || type.contains("89504E47") //PNG
                || type.contains("47494638") //GIF
                || type.contains("49492A00") //TIFF(tif)
                || type.contains("424D") //Bitmap(bmp)
        ) {
            return true;
        }
        return false;
    }

    //将文件头转换成16进制字符串
    public static String bytesToHexString(byte[] src) {
        StringBuilder builder = new StringBuilder();
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 0; i < src.length; i++) {
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                builder.append(0);
            }
            builder.append(hv);
        }
        return builder.toString();
    }

}

一、word文件转pdf文件（支持doc、docx）

word转pdf的方法比较简单，aspose-words基本都被帮我们搞定了，doc、docx都能支持。

代码：

public static void wordToPdf(String wordPath, String pdfPath) throws Exception {
        pdfPath = FileUtil.getNewFileFullPath(wordPath, pdfPath, "pdf");
        File file = new File(pdfPath);
        FileOutputStream os = new FileOutputStream(file);
        Document doc = new Document(wordPath);
        doc.save(os, com.aspose.words.SaveFormat.PDF);
    }

验证代码：

public static void main(String[] args) throws Exception {
        wordToPdf("D:\\书籍\\电子书\\其它\\《山海经》异兽图.docx", "D:\\test");
    }

转换效果如下，格式、图文都没什么问题，doc、docx经过验证也都能转换成功

二、txt文件转pdf文件

txt文件转pdf文件代码直接复用word的即可

代码:

public static void txtToPdf(String txtPath, String pdfPath) throws Exception {
        wordToPdf(txtPath, pdfPath);
    }

验证代码：

public static void main(String[] args) throws Exception {
        txtToPdf("D:\\书籍\\电子书\\国外名著\\君主论.txt", "D:\\test");
    }

转换效果如下

三、PPT文件转pdf文件（支持ppt、pptx）

PPT文件转pdf文件，听说你们公司不让用ppt，那就让我们把ppt转成pdf再用吧。其实从这里开始代码就开始复杂起来了，这里用到了Apache poi、itextpdf、Graphics2D三个库，于是我结合这三个库同时兼容ppt、pptx写出了第一版代码

ppt转pdf第一版代码

public static void pptToPdf(String pptPath, String pdfPath) throws IOException {
        pdfPath = FileUtil.getNewFileFullPath(pptPath, pdfPath, "pdf");
        com.itextpdf.text.Document document = null;
        FileOutputStream fileOutputStream = null;
        PdfWriter pdfWriter = null;
        try {
            InputStream inputStream = Files.newInputStream(Paths.get(pptPath));
            SlideShow slideShow;
            String ext = pptPath.substring(pptPath.lastIndexOf("."));
            if (ext.equals(".pptx")) {
                slideShow = new XMLSlideShow(inputStream);
            } else {
                slideShow = new HSLFSlideShow(inputStream);
            }
            Dimension dimension = slideShow.getPageSize();
            fileOutputStream = new FileOutputStream(pdfPath);
            //document = new com.itextpdf.text.Document(new com.itextpdf.text.Rectangle((float) dimension.getWidth(), (float) dimension.getHeight()));
            document = new com.itextpdf.text.Document();
            pdfWriter = PdfWriter.getInstance(document, fileOutputStream);
            document.open();
            for (Slide slide : slideShow.getSlides()) {
                // 设置字体, 解决中文乱码
                setPPTFont(slide, "宋体");
                BufferedImage bufferedImage = new BufferedImage((int) dimension.getWidth(), (int) dimension.getHeight(), BufferedImage.TYPE_INT_RGB);
                Graphics2D graphics2d = bufferedImage.createGraphics();
                graphics2d.setPaint(Color.white);
                graphics2d.setFont(new java.awt.Font("宋体", java.awt.Font.PLAIN, 12));
                slide.draw(graphics2d);
                graphics2d.dispose();
                com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(bufferedImage, null);
                image.scaleToFit((float) dimension.getWidth(), (float) dimension.getHeight());
                document.add(image);
                document.newPage();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (document != null) {
                    document.close();
                }
                if (fileOutputStream != null) {
                    fileOutputStream.close();
                }
                if (pdfWriter != null) {
                    pdfWriter.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private static void setPPTFont(Slide slide, String fontFamily) {
        // 设置字体, 解决中文乱码
        for (Shape shape : slide.getShapes()) {
            if (shape instanceof TextShape) {
                TextShape textShape = (TextShape) shape;
                List textParagraphs = textShape.getTextParagraphs();
                for (TextParagraph textParagraph : textParagraphs) {
                    List textRuns = textParagraph.getTextRuns();
                    for (TextRun textRun : textRuns) {
                        textRun.setFontFamily(fontFamily);
                    }
                }
            }
        }
    }

验证代码：

public static void main(String[] args) throws Exception {
        pptToPdf("C:\\Users\\jie\\Desktop\\预览\\web\\files\\河西走廊见闻录.pptx", "D:\\test");
    }

转换效果如下

可以看到转换效果并不怎么好，ppt的内容展示不全。于是我开始在网上找解决方案，结果找到了一个很神奇的解决方案，就绘制的图片先写在一个PdfPTable对象上，再把PdfPTable对象放到document离去，于是我根据这个改了改代码写出了第二版代码

ppt转pdf第二版代码

public static void pptToPdf(String pptPath, String pdfPath) throws IOException {
        pdfPath = FileUtil.getNewFileFullPath(pptPath, pdfPath, "pdf");
        com.itextpdf.text.Document document = null;
        FileOutputStream fileOutputStream = null;
        PdfWriter pdfWriter = null;
        try {
            InputStream inputStream = Files.newInputStream(Paths.get(pptPath));
            SlideShow slideShow;
            String ext = pptPath.substring(pptPath.lastIndexOf("."));
            if (ext.equals(".pptx")) {
                slideShow = new XMLSlideShow(inputStream);
            } else {
                slideShow = new HSLFSlideShow(inputStream);
            }
            Dimension dimension = slideShow.getPageSize();
            fileOutputStream = new FileOutputStream(pdfPath);
            //document = new com.itextpdf.text.Document(new com.itextpdf.text.Rectangle((float) dimension.getWidth(), (float) dimension.getHeight()));
            document = new com.itextpdf.text.Document();
            pdfWriter = PdfWriter.getInstance(document, fileOutputStream);
            document.open();
            PdfPTable pdfPTable = new PdfPTable(1);
            for (Slide slide : slideShow.getSlides()) {
                // 设置字体, 解决中文乱码
                setPPTFont(slide, "宋体");
                BufferedImage bufferedImage = new BufferedImage((int) dimension.getWidth(), (int) dimension.getHeight(), BufferedImage.TYPE_INT_RGB);
                Graphics2D graphics2d = bufferedImage.createGraphics();
                graphics2d.setPaint(Color.white);
                graphics2d.setFont(new java.awt.Font("宋体", java.awt.Font.PLAIN, 12));
                slide.draw(graphics2d);
                graphics2d.dispose();
                com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(bufferedImage, null);
                image.scaleToFit((float) dimension.getWidth(), (float) dimension.getHeight());
                // 写入单元格
                pdfPTable.addCell(new PdfPCell(image, true));
                document.add(pdfPTable);
                pdfPTable.deleteBodyRows();
                document.newPage();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (document != null) {
                    document.close();
                }
                if (fileOutputStream != null) {
                    fileOutputStream.close();
                }
                if (pdfWriter != null) {
                    pdfWriter.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

转换效果如下

可以看到ppt内容已经展示完整了，到此其实ppt转pdf功能已经基本实现了，但是显示效果依然不算完美毕竟我们其实想要的是在pdf里和在ppt看的是一样的效果，而且每页ppt的长宽其实都是一样的，所以我就在想能不能设置pdf每页的长宽，把pdf每页的长宽设置成和ppt的长宽一样。于是我开始看初始化pdf document的源码配置

com.itextpdf.text.Document document = new com.itextpdf.text.Document();

然后发现com.itextpdf.text.Document除了默认的构造函数外还有这这样一个构造函数：

public Document(Rectangle pageSize) {
        this(pageSize, 36.0F, 36.0F, 36.0F, 36.0F);
    }

然后com.itextpdf.text.Rectangle类点进去就发现了可以设置长宽的构造函数：

public Rectangle(float urx, float ury) {
        this(0.0F, 0.0F, urx, ury);
    }

于是我代码中的初始化Document进行如下调整（根据第一版代码改，第二版的PdfPTable可以不用了）

document = new com.itextpdf.text.Document();
//改成如下
document = new com.itextpdf.text.Document(new com.itextpdf.text.Rectangle((float) dimension.getWidth(), (float) dimension.getHeight()));

ppt转pdf第三版代码（最终版）

public static void pptToPdf(String pptPath, String pdfPath) throws IOException {
        pdfPath = FileUtil.getNewFileFullPath(pptPath, pdfPath, "pdf");
        com.itextpdf.text.Document document = null;
        FileOutputStream fileOutputStream = null;
        PdfWriter pdfWriter = null;
        try {
            InputStream inputStream = Files.newInputStream(Paths.get(pptPath));
            SlideShow slideShow;
            String ext = pptPath.substring(pptPath.lastIndexOf("."));
            if (ext.equals(".pptx")) {
                slideShow = new XMLSlideShow(inputStream);
            } else {
                slideShow = new HSLFSlideShow(inputStream);
            }
            Dimension dimension = slideShow.getPageSize();
            fileOutputStream = new FileOutputStream(pdfPath);
            //document = new com.itextpdf.text.Document();
            document = new com.itextpdf.text.Document(new com.itextpdf.text.Rectangle((float) dimension.getWidth(), (float) dimension.getHeight()));
            pdfWriter = PdfWriter.getInstance(document, fileOutputStream);
            document.open();
            for (Slide slide : slideShow.getSlides()) {
                // 设置字体, 解决中文乱码
                setPPTFont(slide, "宋体");
                BufferedImage bufferedImage = new BufferedImage((int) dimension.getWidth(), (int) dimension.getHeight(), BufferedImage.TYPE_INT_RGB);
                Graphics2D graphics2d = bufferedImage.createGraphics();
                graphics2d.setPaint(Color.white);
                graphics2d.setFont(new java.awt.Font("宋体", java.awt.Font.PLAIN, 12));
                slide.draw(graphics2d);
                graphics2d.dispose();
                com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(bufferedImage, null);
                image.scaleToFit((float) dimension.getWidth(), (float) dimension.getHeight());
                document.add(image);
                document.newPage();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (document != null) {
                    document.close();
                }
                if (fileOutputStream != null) {
                    fileOutputStream.close();
                }
                if (pdfWriter != null) {
                    pdfWriter.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

转换效果如下

现在展示的效果已经和ppt上一样了，而且经过验证ppt和pptx都是可以转换成功的。

四、图片转pdf文件

图片转pdf用到了用到了Apache poi、itextpdf两个库，因为itextpdf支持解析的图片有限，点开c读取图片的方法com.itextpdf.text.Image.getInstance，我们可以看到这样一段源码:

 Image img;
            if (c1 == 71 && c2 == 73 && c3 == 70) {
                GifImage gif = new GifImage(url);
                img = gif.getImage(1);
                img = img;
                return img;
            }

            if (c1 == 255 && c2 == 216) {
                Jpeg var39 = new Jpeg(url);
                return var39;
            }

            Jpeg2000 var38;
            if (c1 == 0 && c2 == 0 && c3 == 0 && c4 == 12) {
                var38 = new Jpeg2000(url);
                return var38;
            }

            if (c1 == 255 && c2 == 79 && c3 == 255 && c4 == 81) {
                var38 = new Jpeg2000(url);
                return var38;
            }

            if (c1 == PngImage.PNGID[0] && c2 == PngImage.PNGID[1] && c3 == PngImage.PNGID[2] && c4 == PngImage.PNGID[3]) {
                var12 = PngImage.getImage(url);
                return var12;
            }

            if (c1 == 215 && c2 == 205) {
                ImgWMF var37 = new ImgWMF(url);
                return var37;
            }

            if (c1 != 66 || c2 != 77) {
                RandomAccessFileOrArray ra;
                String file;
                if (c1 == 77 && c2 == 77 && c3 == 0 && c4 == 42 || c1 == 73 && c2 == 73 && c3 == 42 && c4 == 0) {
                    ra = null;

                    try {
                        if (url.getProtocol().equals("file")) {
                            file = url.getFile();
                            file = Utilities.unEscapeURL(file);
                            ra = new RandomAccessFileOrArray(randomAccessSourceFactory.createBestSource(file));
                        } else {
                            ra = new RandomAccessFileOrArray(randomAccessSourceFactory.createSource(url));
                        }

                        img = TiffImage.getTiffImage(ra, 1);
                        img.url = url;
                        img = img;
                        return img;
                    } catch (RuntimeException var32) {
                        if (recoverFromImageError) {
                            img = TiffImage.getTiffImage(ra, recoverFromImageError, 1);
                            img.url = url;
                            Image var15 = img;
                            return var15;
                        }

                        throw var32;
                    } finally {
                        if (ra != null) {
                            ra.close();
                        }

                    }
                }

                if (c1 == 151 && c2 == 74 && c3 == 66 && c4 == 50 && c5 == 13 && c6 == 10 && c7 == 26 && c8 == 10) {
                    ra = null;

                    try {
                        if (url.getProtocol().equals("file")) {
                            file = url.getFile();
                            file = Utilities.unEscapeURL(file);
                            ra = new RandomAccessFileOrArray(randomAccessSourceFactory.createBestSource(file));
                        } else {
                            ra = new RandomAccessFileOrArray(randomAccessSourceFactory.createSource(url));
                        }

                        img = JBIG2Image.getJbig2Image(ra, 1);
                        img.url = url;
                        img = img;
                        return img;
                    } finally {
                        if (ra != null) {
                            ra.close();
                        }

                    }
                }

由此可以可知itextpdf支持解析的图片只有gif、jpeg、png、bmp、wmf、tiff、 jbig2这几种，这些其实已经基本包含了所有主流的图片格式（百度图片：所以我用的webp格式是非主流格式？），而且图片格式不是光改后缀就行的，必须要用格式转换器转换。比如下面这张图虽然后缀是jpeg，但通过查看图片信息可知实际格式是webg格式itextpdf一样无法解析

话不多说我们先结合Apache poi、itextpdf两个库简单协议版基本的图片转换pdf代码

单图片转pdf第一版代码

public static void imageToPdf(String imgPath, String pdfPath) throws Exception {
        pdfPath = FileUtil.getNewFileFullPath(imgPath, pdfPath, "pdf");
        com.itextpdf.text.Document document = new com.itextpdf.text.Document();
        PdfWriter.getInstance(document, Files.newOutputStream(Paths.get(pdfPath)));
        document.open();
        com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(imgPath);
        image.setAlignment(com.itextpdf.text.Image.ALIGN_CENTER);
        document.add(image);
        document.close();
    }

验证代码：

public static void main(String[] args) throws Exception {
       imageToPdf("D:\\picture\\美女\\aa37a7be4196c07f43a3f776801d1b46.jpg", "D:\\test");
    }

转换效果如下

从效果可以我们可以看到这个图片其实是没有显示完全的， 其实小一点的图片是没什么问题的，但是因为pdf设置的每页都是A4大小，所以在图片过大时会显示不完整，所以我们在图片过大时需要对图片进行一些调整，调整后的代码如下：

单图片转pdf第二版代码

public static void imageToPdf(String imgPath, String pdfPath) throws Exception {
        pdfPath = FileUtil.getNewFileFullPath(imgPath, pdfPath, "pdf");
        com.itextpdf.text.Document document = new com.itextpdf.text.Document();
        PdfWriter.getInstance(document, Files.newOutputStream(Paths.get(pdfPath)));
        document.open();
        com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(imgPath);
        float width = image.getWidth();
        float height = image.getHeight();
        float space = 50f;
        if (width > PageSize.A4.getWidth() - space || height > PageSize.A4.getHeight() - space) {
            image.scaleToFit(PageSize.A4.getWidth() - space, PageSize.A4.getHeight() - space);
        }
        image.setAlignment(com.itextpdf.text.Image.ALIGN_CENTER);
        document.add(image);
        document.close();
    }

转换效果如下

可以看到现在图片已经完整的显示在pdf的页面中了，到这里你可能会有一个疑惑，为什么这次不想上面ppt转换pdf一样把pdf的页面长宽设置成和图片一样，而且去调整图片的大小呢。之所以这样做的原因是因为在接下来的多图片转换成一个pdf文件时，往往是不能确保每张图片的长宽比例是一样的，为了确保每张图片都能完整的显示，所以只能调整图片的大小。

将文件夹下的所有图片导成一个pdf

将图片一张一张的导成pdf毕竟很麻烦，比如我一个文件夹下面有很多张图片，我想将该文件夹下的所有图片都导入pdf中做个《美人谱》，我该怎么做呢？安排！于是代码调整成了下面这样

支持多图片转pdf代码：

public static void imageToPdf(String imagePath, String pdfPath) throws Exception {
        pdfPath = FileUtil.getNewFileFullPath(imagePath, pdfPath, "pdf");
        File imageFile = new File(imagePath);
        File[] files;
        if (imageFile.isDirectory()) {
            files = imageFile.listFiles();
        } else {
            files = new File[]{imageFile};
        }
        imageToPdf(files, pdfPath);
    }

    public static void imageToPdf(File[] imageFiles, String pdfPath) throws Exception {
        com.itextpdf.text.Document document = new com.itextpdf.text.Document();
        PdfWriter.getInstance(document, Files.newOutputStream(Paths.get(pdfPath)));
        document.open();
        for (File file : imageFiles) {
            if (file.isFile() && FileUtil.isImage(file)) {
                try {
                    com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(file.getAbsolutePath());
                    float width = image.getWidth();
                    float height = image.getHeight();
                    float space = 10f;
                    if (width > PageSize.A4.getWidth() - space || height > PageSize.A4.getHeight() - space) {
                        image.scaleToFit(PageSize.A4.getWidth() - space, PageSize.A4.getHeight() - space);
                    }
                    image.setAlignment(com.itextpdf.text.Image.ALIGN_CENTER);
                    //document.setMargins(50, 150, 50, 50);
                    //document.setPageSize(new com.itextpdf.text.Rectangle(width, height));
                    document.newPage();
                    document.add(image);
                } catch (Exception e) {
                    logger.error("图片转换失败", e);
                }
            }
        }
        document.close();
    }

验证代码：

public static void main(String[] args) throws Exception {
       imageToPdf("D:\\picture\\美女", "D:\\test\\美人谱.pdf");
    }

转换效果如下

五、excel文件转pdf文件

其实excel转pdf在实际的应用场景中应该比较罕见，但是前面也说了这么多文件转pdf的方式了，那excel转pdf也就一并说说吧。

方式1 使用itextpdf

代码如下：

public static void excelToPdf(String excelPath, String pdfPath) throws DocumentException, IOException {
        pdfPath = FileUtil.getNewFileFullPath(excelPath, pdfPath, "pdf");
        try (Workbook workbook = WorkbookFactory.create(new File(excelPath))) {
            com.itextpdf.text.Document document = new com.itextpdf.text.Document();
            PdfWriter.getInstance(document, new FileOutputStream(pdfPath));
            document.open();
            BaseFont chineseFont = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.NOT_EMBEDDED);
            Font font = new Font(chineseFont, 12, Font.NORMAL);
            DecimalFormat df = new DecimalFormat("#");
            for (Sheet sheet : workbook) {
                PdfPTable table = new PdfPTable(sheet.getRow(0).getPhysicalNumberOfCells());
                for (Row row : sheet) {
                    for (Cell cell : row) {
                        if (cell.getCellType() == CellType.NUMERIC) {
                            PdfPCell pdfPCell = new PdfPCell(new Paragraph(df.format(cell.getNumericCellValue()), font));
                            table.addCell(pdfPCell);
                        } else {
                            PdfPCell pdfPCell = new PdfPCell(new Paragraph(cell.toString(), font));
                            table.addCell(pdfPCell);
                        }
                    }
                }
                table.setHeaderRows(1);
                document.add(table);
            }
            document.close();
        }
    }

验证代码：

public static void main(String[] args) throws Exception {
       excelToPdf("C:\\Users\\jie\\Desktop\\新建 Microsoft Excel 工作表.xlsx", "D:\\test");
    }

转换效果如下

方式2 使用spire

因为spire不在maven中央仓库里以及阿里云的maven仓库中，所以在使用spire之前需要现在maven中配置新的maven仓库地址，配置如下;

        
            com.e-iceblue
            e-iceblue
            https://repo.e-iceblue.cn/repository/maven-public/
        
    

然后再pom中引入依赖：

收费：

e-iceblue
            spire.office
            5.3.1
        

或者 免费的：

e-iceblue
            spire.office.free
            5.3.1
        

免费版本基础功能都能用

代码：

public static void excelToPdf2(String excelPath, String pdfPath) throws DocumentException, IOException, InvalidFormatException {
        pdfPath = FileUtil.getNewFileFullPath(excelPath, pdfPath, "pdf");
        com.spire.xls.Workbook wb = new com.spire.xls.Workbook();
        wb.loadFromFile(excelPath);
        wb.saveToFile(pdfPath, com.spire.xls.FileFormat.PDF);
    }

验证代码：

public static void main(String[] args) throws Exception {
       excelToPdf2("C:\\Users\\jie\\Desktop\\新建 Microsoft Excel 工作表.xlsx", "D:\\test");
    }

转换效果如下

工具类整体代码

好了到这里就已经将word、txt、ppt、excel、图片等文件转成pdf文件实现方式已经全部说完了，感谢阅读到这里的朋友！最后附上文中用到的工具类的整体代码：

package com.fhey.service.common.utils.file;

import cn.hutool.core.util.StrUtil;
import com.aspose.words.Document;
import com.fhey.service.common.utils.FileUtil;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Font;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.BaseFont;
import com.itextpdf.text.pdf.PdfPCell;
import com.itextpdf.text.pdf.PdfPTable;
import com.itextpdf.text.pdf.PdfWriter;
import org.apache.poi.hslf.usermodel.*;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.sl.usermodel.Shape;
import org.apache.poi.sl.usermodel.*;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xslf.usermodel.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.awt.Color;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.text.DecimalFormat;
import java.util.List;


public class FileConvertUtil {
    private static final Logger logger = LoggerFactory.getLogger(FileConvertUtil2.class);

    //将word转成pdf
    public static void wordToPdf(String wordPath, String pdfPath) throws Exception {
        pdfPath = FileUtil.getNewFileFullPath(wordPath, pdfPath, "pdf");
        File file = new File(pdfPath);
        FileOutputStream os = new FileOutputStream(file);
        Document doc = new Document(wordPath);
        doc.save(os, com.aspose.words.SaveFormat.PDF);
    }

    //将txt转成pdf
    public static void txtToPdf(String txtPath, String pdfPath) throws Exception {
        wordToPdf(txtPath, pdfPath);
    }

    //将图片转成pdf
    public static void imageToPdf(String imagePath, String pdfPath) throws Exception {
        pdfPath = FileUtil.getNewFileFullPath(imagePath, pdfPath, "pdf");
        File imageFile = new File(imagePath);
        File[] files;
        if (imageFile.isDirectory()) {
            files = imageFile.listFiles();
        } else {
            files = new File[]{imageFile};
        }
        imageToPdf(files, pdfPath);
    }

    //将图片转成pdf
    public static void imageToPdf(File[] imageFiles, String pdfPath) throws Exception {
        com.itextpdf.text.Document document = new com.itextpdf.text.Document();
        PdfWriter.getInstance(document, Files.newOutputStream(Paths.get(pdfPath)));
        document.open();
        for (File file : imageFiles) {
            if (file.isFile() && FileUtil.isImage(file)) {
                try {
                    com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(file.getAbsolutePath());
                    float width = image.getWidth();
                    float height = image.getHeight();
                    float space = 10f;
                    if (width > PageSize.A4.getWidth() - space || height > PageSize.A4.getHeight() - space) {
                        image.scaleToFit(PageSize.A4.getWidth() - space, PageSize.A4.getHeight() - space);
                    }
                    image.setAlignment(com.itextpdf.text.Image.ALIGN_CENTER);
                    //document.setMargins(50, 150, 50, 50);
                    //document.setPageSize(new com.itextpdf.text.Rectangle(width, height));
                    document.newPage();
                    document.add(image);
                } catch (Exception e) {
                    logger.error("图片转换失败", e);
                }
            }
        }
        document.close();
    }


    //将excel文件转成pdf
    public static void excelToPdf(String excelPath, String pdfPath) throws DocumentException, IOException {
        pdfPath = FileUtil.getNewFileFullPath(excelPath, pdfPath, "pdf");
        try (Workbook workbook = WorkbookFactory.create(new File(excelPath))) {
            com.itextpdf.text.Document document = new com.itextpdf.text.Document();
            PdfWriter.getInstance(document, new FileOutputStream(pdfPath));
            document.open();
            BaseFont chineseFont = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.NOT_EMBEDDED);
            Font font = new Font(chineseFont, 12, Font.NORMAL);
            DecimalFormat df = new DecimalFormat("#");
            for (Sheet sheet : workbook) {
                PdfPTable table = new PdfPTable(sheet.getRow(0).getPhysicalNumberOfCells());
                for (Row row : sheet) {
                    for (Cell cell : row) {
                        if (cell.getCellType() == CellType.NUMERIC) {
                            PdfPCell pdfPCell = new PdfPCell(new Paragraph(df.format(cell.getNumericCellValue()), font));
                            table.addCell(pdfPCell);
                        } else {
                            PdfPCell pdfPCell = new PdfPCell(new Paragraph(cell.toString(), font));
                            table.addCell(pdfPCell);
                        }
                    }
                }
                table.setHeaderRows(1);
                document.add(table);
            }
            document.close();
        }
    }

    //将excel文件转成pdf
    public static void excelToPdf2(String excelPath, String pdfPath) throws DocumentException, IOException, InvalidFormatException {
        pdfPath = FileUtil.getNewFileFullPath(excelPath, pdfPath, "pdf");
        com.spire.xls.Workbook wb = new com.spire.xls.Workbook();
        wb.loadFromFile(excelPath);
        wb.saveToFile(pdfPath, com.spire.xls.FileFormat.PDF);
    }

    //将html转成pdf
    public static void htmlToPdf(String htmlPath, String pdfPath) {
        try {
            pdfPath = FileUtil.getNewFileFullPath(pdfPath, pdfPath, "pdf");
            File file = new File(pdfPath); // 新建一个空白pdf文档
            FileOutputStream os = new FileOutputStream(file);
            Document doc = new Document(htmlPath); // Address是将要被转化的word文档
            doc.save(os, com.aspose.words.SaveFormat.PDF);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //将ppt文件转成pdf
    public static void pptToPdf(String pptPath, String pdfPath) throws IOException {
        pdfPath = FileUtil.getNewFileFullPath(pptPath, pdfPath, "pdf");
        com.itextpdf.text.Document document = null;
        FileOutputStream fileOutputStream = null;
        PdfWriter pdfWriter = null;
        try {
            InputStream inputStream = Files.newInputStream(Paths.get(pptPath));
            SlideShow slideShow;
            String ext = pptPath.substring(pptPath.lastIndexOf("."));
            if (ext.equals(".pptx")) {
                slideShow = new XMLSlideShow(inputStream);
            } else {
                slideShow = new HSLFSlideShow(inputStream);
            }
            Dimension dimension = slideShow.getPageSize();
            fileOutputStream = new FileOutputStream(pdfPath);
            //document = new com.itextpdf.text.Document();
            document = new com.itextpdf.text.Document(new com.itextpdf.text.Rectangle((float) dimension.getWidth(), (float) dimension.getHeight()));
            pdfWriter = PdfWriter.getInstance(document, fileOutputStream);
            document.open();
            for (Slide slide : slideShow.getSlides()) {
                // 设置字体, 解决中文乱码
                setPPTFont(slide, "宋体");
                BufferedImage bufferedImage = new BufferedImage((int) dimension.getWidth(), (int) dimension.getHeight(), BufferedImage.TYPE_INT_RGB);
                Graphics2D graphics2d = bufferedImage.createGraphics();
                graphics2d.setPaint(Color.white);
                graphics2d.setFont(new java.awt.Font("宋体", java.awt.Font.PLAIN, 12));
                slide.draw(graphics2d);
                graphics2d.dispose();
                com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance(bufferedImage, null);
                image.scaleToFit((float) dimension.getWidth(), (float) dimension.getHeight());
                document.add(image);
                document.newPage();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (document != null) {
                    document.close();
                }
                if (fileOutputStream != null) {
                    fileOutputStream.close();
                }
                if (pdfWriter != null) {
                    pdfWriter.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private static void setPPTFont(Slide slide, String fontFamily) {
        // 设置字体, 解决中文乱码
        for (Shape shape : slide.getShapes()) {
            if (shape instanceof TextShape) {
                TextShape textShape = (TextShape) shape;
                List textParagraphs = textShape.getTextParagraphs();
                for (TextParagraph textParagraph : textParagraphs) {
                    List textRuns = textParagraph.getTextRuns();
                    for (TextRun textRun : textRuns) {
                        textRun.setFontFamily(fontFamily);
                    }
                }
            }
        }
    }
}