简介

在项目中我们有时候会遇到操作PDF文件的需求，如将PDF的每一页转换成图片，今天我们就来实现一下相关功能。

实现

引入依赖

org.apache.pdfbox

pdfbox

2.0.21

pdfbox是一个开源的操作PDF的工具包，这里是 官方文档

将PDF转换成多张图片

import java.awt.image.BufferedImage;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileOutputStream;

import java.util.ArrayList;

import java.util.List;

import java.util.concurrent.atomic.AtomicInteger;

import javax.imageio.ImageIO;

import org.apache.pdfbox.pdmodel.PDDocument;

import org.apache.pdfbox.rendering.PDFRenderer;

public class Client {

public static void main(String[] args) throws Exception {

testPdf2images();

}

private static void testPdf2images() throws Exception {

List images = pdf2images(new File("D:/testpdf/阿里巴巴Java开发...1528284352.pdf"));

AtomicInteger fileNameIndex = new AtomicInteger(1);

for (byte[] image : images) {

new ByteArrayInputStream(image).transferTo(

new FileOutputStream("D:/testpdf/" + fileNameIndex.getAndIncrement() + ".png"));

}

}

/**

* 将PDF文件转换成多张图片

*

* @param pdfFile PDF源文件

* @return 图片字节数组列表

*/

private static List pdf2images(File pdfFile) throws Exception {

//加载PDF

PDDocument pdDocument = PDDocument.load(pdfFile);

//创建PDF渲染器

PDFRenderer renderer = new PDFRenderer(pdDocument);

int pages = pdDocument.getNumberOfPages();

List images = new ArrayList<>();

for (int i = 0; i < pages; i++) {

ByteArrayOutputStream output = new ByteArrayOutputStream();

//将PDF的每一页渲染成一张图片

BufferedImage image = renderer.renderImage(i);

ImageIO.write(image, "png", output);

images.add(output.toByteArray());

}

pdDocument.close();

return images;

}

}

创建的图片列表如下

将图片列表转换成PDF

import java.awt.image.BufferedImage;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.util.Arrays;

import java.util.Objects;

import javax.imageio.ImageIO;

import org.apache.pdfbox.pdmodel.PDDocument;

import org.apache.pdfbox.pdmodel.PDPage;

import org.apache.pdfbox.pdmodel.PDPageContentStream;

import org.apache.pdfbox.pdmodel.common.PDRectangle;

import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;

public class Client2 {

public static void main(String[] args) throws Exception {

testImages2pdf();

}

private static void testImages2pdf() throws Exception {

File file = new File("D:/testpdf");

//过滤所有图片文件

File[] files = file.listFiles((f, s) -> s.endsWith(".png"));

if (Objects.nonNull(files)) {

//根据名称排序

Arrays.sort(files, Client2::compareImageFile);

byte[] pdf = images2pdf(files);

new ByteArrayInputStream(pdf).transferTo(

new FileOutputStream("D:/testpdf/阿里巴巴java文档.pdf"));

}

}

/**

* 根据图片名称排序

*/

private static int compareImageFile(File f1, File f2) {

String f1Name = f1.getName();

String f2Name = f2.getName();

return Integer.compare(Integer.parseInt(f1Name.substring(0, f1Name.lastIndexOf("."))),

Integer.parseInt(f2Name.substring(0, f2Name.lastIndexOf("."))));

}

/**

* 根据多张图片生成PDF文件

*

* @param images 图片列表

* @return PDF文件

*/

private static byte[] images2pdf(File... images) throws Exception {

//创建空PDF

PDDocument document = new PDDocument();

for (File image : images) {

InputStream input = new FileInputStream(image);

//读取图片

BufferedImage bufferedImage = ImageIO.read(input);

float width = bufferedImage.getWidth();

float height = bufferedImage.getHeight();

//创建PDF的一页

PDPage page = new PDPage(new PDRectangle(width, height));

document.addPage(page);

PDImageXObject pdImageXObject = PDImageXObject.createFromFileByContent(image, document);

PDPageContentStream contentStream = new PDPageContentStream(document, page);

//写入图片

contentStream.drawImage(pdImageXObject, 0, 0);

contentStream.close();

input.close();

}

ByteArrayOutputStream output = new ByteArrayOutputStream();

document.save(output);

document.close();

return output.toByteArray();

}

}

总结

遇到问题多google

参考