java 读取PDF文件生成图片形式

	<!-- PDF转图片 -->
    <dependency>
        <groupId>org.icepdf.os</groupId>
        <artifactId>icepdf-core</artifactId>
        <version>6.2.2</version>
        <exclusions>
            <exclusion>
                <groupId>javax.media</groupId>
                <artifactId>jai_core</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

package com.util;

import com.lowagie.text.pdf.PdfReader;
import lombok.extern.slf4j.Slf4j;
import org.icepdf.core.pobjects.Document;
import org.icepdf.core.pobjects.Page;
import org.icepdf.core.util.GraphicsRenderingHints;
import org.springframework.web.multipart.MultipartFile;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

//java 项目 www.fhadmin.org
@Slf4j
public class PdfToImageUtil {

    //支持文件格式
    public static final String SUPPORT_FILE = "pdf";
    //图片文件格式
    public static final String IMAGE_SUFFIX = "jpg"; //png
    //压缩文件格式
    public static final String ZIP_SUFFIX = "zip";
    //PDF是否为一页
    private static boolean isImage;

    /**
     * 对外的开放接口，用于将PDF文件转换为图片文件压缩包进行下载
     * @param file SpringMVC获取的图片文件
     */
    public static synchronized void pdfToTransformation(MultipartFile file, HttpServletResponse response) throws Exception {
        String fileName = file.getOriginalFilename();
        if(null == fileName) return;
        String suffix = fileName.substring(fileName.lastIndexOf(".") + 1);
        log.info("文件名称：" + fileName + ",文件后缀：" + suffix);
        if(!SUPPORT_FILE.equals(suffix)) return;
        isImage = false;
        File imageFile = generateFile(file);
        log.info("文件生成成功!");
        downloadFile(imageFile, response);
    }

    /**
     * 将PDF文件转换为多张图片并放入一个压缩包中
     * @param file SpringMVC获取的图片文件
     * @return 图片文件压缩包
     * @throws Exception 抛出异常
     */
    private static File generateFile(MultipartFile file) throws Exception {
        String fileName = file.getOriginalFilename();
        if(null == fileName) return null;
        Document document = new Document();
        document.setByteArray(file.getBytes(), 0, file.getBytes().length, fileName);
        log.info("PDF页数：" + document.getNumberOfPages());
        isImage = 1 == document.getNumberOfPages();
        File imageReturnFile = null;
        List<File> fileList = new ArrayList<>();
        for (int i = 0; i < document.getNumberOfPages(); i++) {
            BufferedImage image = (BufferedImage) document.getPageImage(i, GraphicsRenderingHints.SCREEN,
                    Page.BOUNDARY_CROPBOX, 0F, 2.5F);
            File imageFile = new File((i + 1) + "." + IMAGE_SUFFIX);
            ImageIO.write(image, IMAGE_SUFFIX, imageFile);
            image.flush();
            if(isImage){
                imageReturnFile = imageFile;
                break;
            }
            fileList.add(imageFile);
        }
        document.dispose();
        if(isImage) return imageReturnFile;
        //压缩图片文件
        String directoryName = fileName.substring(0, fileName.lastIndexOf("."));
        File zipFile = new File(directoryName + "." + ZIP_SUFFIX);
        ZipOutputStream zipOutputStream = new ZipOutputStream(new FileOutputStream(zipFile));
        zipFile(fileList, zipOutputStream);
        zipOutputStream.close();
        return zipFile;
    }

    /**
     * 下载image/zip文件
     * @param downloadFile 文件
     * @param response HttpServletResponse
     * @throws IOException IO异常
     */
    private static void downloadFile(File downloadFile, HttpServletResponse response) throws IOException {
        FileInputStream fileInputStream = new FileInputStream(downloadFile);
        byte[] bytes = new byte[fileInputStream.available()];
        fileInputStream.read(bytes);
        fileInputStream.close();
        //设置response参数
        response.reset();
        if(isImage){
            response.setContentType("image/jpeg");
        } else {
            response.setContentType("application/zip");
        }
        response.setCharacterEncoding("UTF-8");
        response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(downloadFile.getName(), "UTF-8"));
        OutputStream outputStream = response.getOutputStream();
        outputStream.write(bytes);
        outputStream.flush();
        outputStream.close();
        if(!isImage) downloadFile.delete();
    }

    /**
     * 压缩文件
     * @param inputFiles 具体需要压缩的文件集合
     * @param zipOutputStream ZipOutputStream对象
     * @throws IOException IO异常
     */
    private static void zipFile(List<File> inputFiles, ZipOutputStream zipOutputStream) throws IOException {
        byte[] buffer = new byte[1024];
        for (File file : inputFiles) {
            if (file.exists()) {
                if (file.isFile()) {
                    BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
                    zipOutputStream.putNextEntry(new ZipEntry(file.getName()));
                    int size = 0;
                    while ((size = bis.read(buffer)) > 0) {
                        zipOutputStream.write(buffer, 0, size);
                    }
                    zipOutputStream.closeEntry();
                    bis.close();
                    file.delete();
                } else {
                    File[] files = file.listFiles();
                    if(null == files) continue;
                    List<File> childrenFileList = Arrays.asList(files);
                    zipFile(childrenFileList, zipOutputStream);
                }
            }
        }
    }

    /**
     * 获取PDF页数
     * @throws IOException
     */
    public static String getPdfPageSize(MultipartFile file) throws IOException {
        PdfReader pdfReader = new PdfReader(file.getBytes());
        int pages = pdfReader.getNumberOfPages();
        return String.valueOf(pages);
    }
}

package com.web.transformation.controller;

import com.util.PdfToImageUtil;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

//java项目 www.fhadmin.org
@Controller
public class PdfController {

    //PDF转图片或者ZIP
    @RequestMapping("/pdfToImage")
    @ResponseBody
    public void pdfToImage(MultipartFile file, HttpServletResponse response) throws Exception{
        PdfToImageUtil.pdfToTransformation(file,response);
    }

    //获取PDF页数
    @RequestMapping("/getPdfPageSize")
    @ResponseBody
    public String pdfToImage(MultipartFile file) throws IOException {
        return PdfToImageUtil.getPdfPageSize(file);
    }

}