Java PDF转图片转PDF

需要用到下面三个库

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>fontbox</artifactId>
    <version>2.0.1</version>
</dependency>
<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.1</version>
</dependency>
<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itextpdf</artifactId>
    <version>5.5.13</version>
</dependency>

下面是代码及示例

import com.itextpdf.text.Document;
import com.itextpdf.text.Image;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.PdfWriter;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.PDFRenderer;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;

public class PdfUtils {

  public static void main(String[] args) throws IOException {
    String fileUrl = "xx.pdf";
    pdfToImg(fileUrl, "C:\code\img", "jpg").forEach(System.out::println);
    
    String targetPdfFile = "hello.pdf";
    List<String> list = Arrays.asList("C:\code\img\0ea9685e5db943d29868a9893f4b0600.jpg",
        "C:\code\img\1a41f1790060466b97ded7f2b0c85588.jpg");
    new File(targetPdfFile).createNewFile();
    imgToPdf(list, targetPdfFile);
  }
  /**
   * PDF转图片 根据页码一页一页转
   *
   * @throws IOException imgType:转换后的图片类型 jpg,png
   */
  public static List<String> pdfToImg(String pdfUrl, String basePath, String imgType) {
    List<String> files = new ArrayList<>();
    PDDocument pdDocument = null;
    /* dpi越大转换后越清晰，相对转换速度越慢 */
    int dpi = 200;
    try {
      pdDocument = getPDDocument(pdfUrl);
      PDFRenderer renderer = new PDFRenderer(pdDocument);
      int pages = pdDocument.getNumberOfPages();
      for (int page = 0; page < pages; page++) {
        String fileName = basePath
            + "/" + UUID.randomUUID().toString().replaceAll("-", "")
            + "." + imgType;
        File f = new File(fileName);
        BufferedImage image = renderer.renderImageWithDPI(page, dpi);
        ImageIO.write(image, imgType, f);
        files.add(fileName);
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (pdDocument != null) {
        try {
          pdDocument.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
    return files;
  }

  public static  void imgToPdf(List<String> imgList, String target) {
    //创建文档
    Document document = new Document();
    //设置文档页边距
    document.setMargins(0,0,0,0);
    FileOutputStream fos = null;
    try {
      fos = new FileOutputStream(target);
      PdfWriter.getInstance(document, fos);
      //打开文档
      document.open();
      document.setPageCount(imgList.size());
      for (String source : imgList) {
        //获取图片的宽高
        Image image = Image.getInstance(source);
        float imageHeight=image.getScaledHeight();
        float imageWidth=image.getScaledWidth();
        //设置页面宽高与图片一致
        Rectangle rectangle = new Rectangle(imageWidth, imageHeight);
        document.setPageSize(rectangle);
        //图片居中
        image.setAlignment(Image.ALIGN_CENTER);
        //新建一页添加图片
        document.newPage();
        document.add(image);
      }
    } catch (Exception ioe) {
      System.out.println(ioe.getMessage());
    } finally {
        //关闭文档
        document.close();
        if (fos != null) {
          try {
            fos.flush();
            fos.close();
          } catch (IOException e) {
            e.printStackTrace();
          }
        }
    }
  }
  public static List<String> pdfToImg(File file, String basePath, String imgType) {
    List<String> files = new ArrayList<>();
    PDDocument pdDocument = null;
    /* dpi越大转换后越清晰，相对转换速度越慢 */
    int dpi = 200;
    try {
      pdDocument = getPDDocument(file);
      PDFRenderer renderer = new PDFRenderer(pdDocument);
      int pages = pdDocument.getNumberOfPages();
      for (int page = 0; page < pages; page++) {
        String fileName = basePath
            + "/" + UUID.randomUUID().toString().replaceAll("-", "")
            + "." + imgType;
        File f = new File(fileName);
        BufferedImage image = renderer.renderImageWithDPI(page, dpi);
        ImageIO.write(image, imgType, f);
        files.add(fileName);
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (pdDocument != null) {
        try {
          pdDocument.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
    return files;
  }

  private static PDDocument getPDDocument(String fileUrl) throws IOException {
    File file = new File(fileUrl);
    FileInputStream inputStream = new FileInputStream(file);
    return PDDocument.load(inputStream);
  }


  private static PDDocument getPDDocument(File file) throws IOException {
    FileInputStream inputStream = new FileInputStream(file);
    return PDDocument.load(inputStream);
  }
}