java操作PDF：转换、合成、切分

将PDF每一页切割成图片

PDFUtils.cutPNG("D:/tmp/1.pdf","D:/tmp/输出图片路径/");

将PDF转换成一张长图片

PDFUtils.transition_ONE_PNG("D:/tmp/1.pdf");

将多张图片合并成一个PDF文件

PDFUtils.merge_PNG("D:/tmp/测试图片/");

将多个PDF合并成一个PDF文件

PDFUtils.merge_PDF("D:/tmp/测试图片/");

取出指定PDF的起始和结束页码作为新的pdf

PDFUtils.getPartPDF("D:/tmp/1.pdf",3,5);

引入依赖

<!--        apache PDF转图片-->
        <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox</artifactId>
            <version>2.0.24</version>
        </dependency>
<!--        itext 图片合成PDF-->
        <dependency>
            <groupId>com.itextpdf</groupId>
            <artifactId>itextpdf</artifactId>
            <version>5.5.13.2</version>
        </dependency>

代码（如下4个java类放在一起直接使用即可）

PDFUtils.java

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Image;
import com.itextpdf.text.pdf.*;
import org.apache.pdfbox.io.MemoryUsageSetting;
import org.apache.pdfbox.multipdf.PDFMergerUtility;
import org.apache.pdfbox.multipdf.Splitter;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
import org.apache.pdfbox.rendering.ImageType;
import org.apache.pdfbox.rendering.PDFRenderer;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * pdf工具类
 */
public class PDFUtils {


    /**
     * PDF分解图片文件
     *
     * @param pdfPath pdf文件路径
     */
    public static void cutPNG(String pdfPath) throws IOException {
        File pdf = new File(pdfPath);
        cutPNG(pdfPath, pdf.getParent() + File.separator + pdf.getName() + "_pngs");
    }

    /**
     * PDF分解图片文件
     *
     * @param pdfPath pdf文件路径
     * @param outPath 输出文件夹路径
     */
    public static void cutPNG(String pdfPath, String outPath) throws IOException {
        File outDir = new File(outPath);
        if (!outDir.exists()) outDir.mkdirs();
        cutPNG(new File(pdfPath), outDir);
    }

    /**
     * PDF分解图片文件
     *
     * @param pdf    pdf文件
     * @param outDir 输出文件夹
     */
    public static void cutPNG(File pdf, File outDir) throws IOException {
        LogUtils.info("PDF分解图片工作开始");
        List<BufferedImage> list = getImgList(pdf);
        LogUtils.info(pdf.getName() + " 一共发现了 " + list.size() + " 页");
        FileUtils.cleanDir(outDir);
        for (int i = 0; i < list.size(); i++) {
            IMGUtils.saveImageToFile(list.get(i), outDir.getAbsolutePath() + File.separator + (i + 1) + ".png");
            LogUtils.info("已保存图片：" + (i + 1) + ".png");
        }
        LogUtils.info("PDF分解图片工作结束，一共分解出" + list.size() + "个图片文件，保存至：" + outDir.getAbsolutePath());
    }

    /**
     * 将pdf文件转换成一张图片
     *
     * @param pdfPath pdf文件路径
     */
    public static void transition_ONE_PNG(String pdfPath) throws IOException {
        transition_ONE_PNG(new File(pdfPath));
    }

    /**
     * 将pdf文件转换成一张图片
     *
     * @param pdf pdf文件
     */
    public static void transition_ONE_PNG(File pdf) throws IOException {
        LogUtils.info("PDF转换长图工作开始");
        List<BufferedImage> list = getImgList(pdf);
        LogUtils.info(pdf.getName() + " 一共发现了 " + list.size() + " 页");
        BufferedImage image = list.get(0);
        for (int i = 1; i < list.size(); i++) {
            image = IMGUtils.verticalJoinTwoImage(image, list.get(i));
        }
        byte[] data = IMGUtils.getBytes(image);
        String imgPath = pdf.getParent() + File.separator + pdf.getName().replaceAll("\\.", "_") + ".png";
        FileUtils.saveDataToFile(imgPath, data);
        LogUtils.info("PDF转换长图工作结束，合成尺寸：" + image.getWidth() + "x" + image.getHeight() + "，合成文件大小：" + data.length / 1024 + "KB，保存至：" + imgPath);
    }


    /**
     * 将PDF文档拆分成图像列表
     *
     * @param pdf PDF文件
     */
    private static List<BufferedImage> getImgList(File pdf) throws IOException {
        PDDocument pdfDoc = PDDocument.load(pdf);
        List<BufferedImage> imgList = new ArrayList<>();
        PDFRenderer pdfRenderer = new PDFRenderer(pdfDoc);
        int numPages = pdfDoc.getNumberOfPages();
        for (int i = 0; i < numPages; i++) {
            BufferedImage image = pdfRenderer.renderImageWithDPI(i, 300, ImageType.RGB);
            imgList.add(image);
        }
        pdfDoc.close();
        return imgList;
    }

    /**
     * 图片合成PDF
     *
     * @param pngsDirPath 图片文件夹路径
     */
    public static void merge_PNG(String pngsDirPath) throws Exception {
        File pngsDir = new File(pngsDirPath);
        merge_PNG(pngsDir, pngsDir.getName() + ".pdf");
    }

    /**
     * 图片合成pdf
     *
     * @param pngsDir 图片文件夹
     * @param pdfName 合成pdf名称
     */
    private static void merge_PNG(File pngsDir, String pdfName) throws Exception {
        File pdf = new File(pngsDir.getParent() + File.separator + pdfName);
        if (!pdf.exists()) pdf.createNewFile();
        File[] pngList = pngsDir.listFiles((dir, name) -> name.toLowerCase().endsWith(".png"));
        LogUtils.info("在" + pngsDir.getAbsolutePath() + "，一共发现" + pngList.length + "个PNG文件");
        Document document = new Document();
        FileOutputStream fo = new FileOutputStream(pdf);
        PdfWriter writer = PdfWriter.getInstance(document, fo);
        document.open();
        for (File f : pngList) {
            document.newPage();
            byte[] bytes = FileUtils.getFileBytes(f);
            Image image = Image.getInstance(bytes);
            float heigth = image.getHeight();
            float width = image.getWidth();
            int percent = getPercent2(heigth, width);
            image.setAlignment(Image.MIDDLE);
            image.scalePercent(percent + 3);// 表示是原来图像的比例;
            document.add(image);
            System.out.println("正在合成" + f.getName());
        }
        document.close();
        writer.close();
        System.out.println("PDF文件生成地址：" + pdf.getAbsolutePath());

    }


    private static int getPercent2(float h, float w) {
        int p = 0;
        float p2 = 0.0f;
        p2 = 530 / w * 100;
        p = Math.round(p2);
        return p;
    }

    /**
     * 多PDF合成
     *
     * @param pngsDirPath pdf所在文件夹路径
     */
    public static void merge_PDF(String pngsDirPath) throws IOException {
        File pngsDir = new File(pngsDirPath);
        merge_PDF(pngsDir, pngsDir.getName() + "_合并.pdf");
    }

    /**
     * 多PDF合成
     *
     * @param pngsDir pdf所在文件夹
     * @param pdfName 合成pdf文件名
     */
    private static void merge_PDF(File pngsDir, String pdfName) throws IOException {
        File[] pdfList = pngsDir.listFiles((dir, name) -> name.toLowerCase().endsWith(".pdf"));
        LogUtils.info("在" + pngsDir.getAbsolutePath() + "，一共发现" + pdfList.length + "个PDF文件");
        PDFMergerUtility pdfMergerUtility = new PDFMergerUtility();
        pdfMergerUtility.setDestinationFileName(pngsDir.getParent() + File.separator + pdfName);
        for (File f : pdfList) {
            pdfMergerUtility.addSource(f);
        }
        pdfMergerUtility.mergeDocuments(MemoryUsageSetting.setupMainMemoryOnly());
    }

    public static void getPartPDF(String pdfPath, int from, int end) throws Exception {
        pdfPath = pdfPath.trim();
        Document document = null;
        PdfCopy copy = null;
        PdfReader reader = new PdfReader(pdfPath);
        int n = reader.getNumberOfPages();
        if (end == 0) {
            end = n;
        }
        document = new Document(reader.getPageSize(1));
        copy = new PdfCopy(document, new FileOutputStream(pdfPath.substring(0, pdfPath.length() - 4) + "_" + from + "_" + end + ".pdf"));
        document.open();
        for (int j = from; j <= end; j++) {
            document.newPage();
            PdfImportedPage page = copy.getImportedPage(reader, j);
            copy.addPage(page);
        }
        document.close();
    }


}

IMGUtils.java

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class IMGUtils {
    /**
     * 将图像转为png文件的字节数据
     * @param image 目标图像
     * @return 返回数据
     */
    public static byte[] getBytes(BufferedImage image){
        return getBytes(image,"png");
    }


    /**
     * 将图像转换为指定媒体文件类型的字节数据
     * @param image  目标图像
     * @param fileType  文件类型（后缀名）
     * @return 返回数据
     */
    public static byte[] getBytes(BufferedImage image,String fileType){
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        try {
            ImageIO.write(image,fileType,outStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return outStream.toByteArray();
    }

    /**
     * 读取图像，通过文件
     * @param filePath 文件路径
     * @return BufferedImage
     */
    public static BufferedImage getImage(String filePath){
        try {
            return ImageIO.read(new FileInputStream(filePath));
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 读取图像，通过字节数据
     * @param data 字节数据
     * @return BufferedImage
     */
    public static BufferedImage getImage(byte[] data){
        try {
            return ImageIO.read(new ByteArrayInputStream(data));
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }


    /**
     * 保存图像到指定文件
     * @param image 图像
     * @param filePath 文件路径
     */
    public static void saveImageToFile(BufferedImage image,String filePath) throws IOException {
        FileUtils.saveDataToFile(filePath,getBytes(image));
    }

    /**
     * 纵向拼接图片
     */
    public static BufferedImage verticalJoinTwoImage(BufferedImage image1, BufferedImage image2){
        if(image1==null)return image2;
        if(image2==null)return image1;
        BufferedImage image=new BufferedImage(image1.getWidth(),image1.getHeight()+image2.getHeight(),image1.getType());
        Graphics2D g2d = image.createGraphics();
        g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2d.drawImage(image1, 0, 0, image1.getWidth(), image1.getHeight(), null);
        g2d.drawImage(image2, 0, image1.getHeight(), image2.getWidth(), image2.getHeight(), null);
        g2d.dispose();// 释放图形上下文使用的系统资源
        return image;
    }


    /**
     * 剪裁图片
     * @param image 对象
     * @param x  顶点x
     * @param y  顶点y
     * @param width   宽度
     * @param height   高度
     * @return 剪裁后的对象
     */
    public static BufferedImage cutImage(BufferedImage image,int x,int y,int width,int height){
        if(image==null)return null;
        return image.getSubimage(x,y,width,height);
    }



}

FileUtils.java

import java.io.*;

public class FileUtils {

    /**
     * 将数据保存到指定文件路径
     */
    public static void saveDataToFile(String filePath,byte[] data) throws IOException {
        File file = new File(filePath);
        if(!file.exists())file.createNewFile() ;
        FileOutputStream outStream = new FileOutputStream(file);
        outStream.write(data);
        outStream.flush();
        outStream.close();
    }

    /**
     * 读取文件数据
     */
    public static byte[] getFileBytes(File file) throws IOException {
        if(!file.exists()||(file.exists()&&!file.isFile()))return null;
        InputStream inStream=new FileInputStream(file);
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        while ((len = inStream.read(buffer)) != -1) {
            outStream.write(buffer, 0, len);
        }
        inStream.close();
        return outStream.toByteArray();
    }

    /**
     * 读取文本文件字
     */
    public static String getFileText(String path){
        try {
            byte[] data= getFileBytes(new File(path));
            return new String(data);
        } catch (Exception e) {
            return "";
        }
    }

    /**
     * 清空文件夹下所有文件
     */
    public static void cleanDir(File dir){
        if(dir!=null&&dir.isDirectory()){
            for(File file:dir.listFiles()){
                if(file.isFile())file.delete();
                if(file.isDirectory())cleanDir(file);
            }
        }
    }


}

LogUtils.java

public class LogUtils {

    public static void info(String context){
        System.out.println(context);
    }

    public static void warn(String context){
        System.out.println(context);
    }

    public static void error(String context){
        System.out.println(context);
    }


}