图片 pdf 互转

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>fontbox</artifactId>
</dependency>
<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
</dependency>
<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox-tools</artifactId>
</dependency>
<dependency>
    <groupId>org.eclipse.birt.runtime.3_7_1</groupId>
    <artifactId>com.lowagie.text</artifactId>
</dependency>

import cn.hutool.http.HttpUtil;
import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.pdf.PdfWriter;
import com.zz.business.service.ImgPdfService;
import com.zz.framework.enums.*;
import com.zz.framework.exception.BusinessException;
import com.zz.framework.utils.DocumentUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPageTree;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;

import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

/**
 * 报告 接口实现类
 *
 * @author Tang Peng
 * @since 1.0.0
 */
@Service
@Slf4j
public class ImgPdfServiceImpl implements ImgPdfService {


    @Override
    public boolean uploadConvertPdf(HttpServletResponse response, MultipartFile[] files, int ratio, String paperSize) {
        response.reset();
        // 设置返回的请求ContentType
        response.setContentType(ContentTypeEnum.DOWNLOAD.getValue());
        // 设置返回的编码类型
        response.setCharacterEncoding(CharacterEncodingEnum.UTF_8.getCode());
        // 设置Content-disposition避免出现中文乱码
        response.setHeader(ResponseHeaderEnum.CONTENT_DISPOSITION.getCode(),
                ResponseHeaderEnum.CONTENT_DISPOSITION.getValue() + System.currentTimeMillis() + ".pdf");
        try {
            OutputStream ops = response.getOutputStream();
            //创建一个文档对象
            Document doc = new Document();
            //定义输出文件的位置
            PdfWriter.getInstance(doc, ops);
            doc.open();
            for (MultipartFile file : files) {
                if (file.getBytes().length == 0) {
                    throw new BusinessException(StatusCode.UPLOAD_FORMAT_IS_EMPTY);
                }
                String originalFilename = file.getOriginalFilename();
                if (StringUtils.isBlank(originalFilename)) {
                    throw new BusinessException(StatusCode.UPLOAD_FORMAT_NO_NAME);
                }
                //文件后缀 带.
                String suffix = getSuffixAndFileName(file)[0];
                //文件格式 不带.
                String fileFormat = suffix.substring(1);
                boolean equalsDot = !FileFormatEnum.DOT.getCode().equals(suffix.substring(0, 1));
                boolean equalsFileFormat = !FileFormatEnum.JPG.getCode().equals(fileFormat) && !FileFormatEnum.PNG.getCode().equals(fileFormat);

                if (equalsDot || equalsFileFormat) {
                    throw new BusinessException(StatusCode.INCORRECT_UPLOAD_FORMAT);
                }
                //默认A4大小
                if (StringUtils.isEmpty(paperSize) || PaperSizeEnum.A4.getSize().equals(paperSize)) {
                    DocumentUtil.docAddImg(doc, file.getBytes(), ratio, PaperSizeEnum.A4.getWidth(), PaperSizeEnum.A4.getHeight());
                }
            }
            // 关闭文档
            doc.close();
            //输出给调用方
            ops.flush();
        } catch (DocumentException e) {
            log.error("ReportServiceImpl#uploadConvertPdf pdf文档生成失败" + e);
            throw new BusinessException(StatusCode.PDF_DOC_HANDLE_EXCEPTION);
        } catch (IOException e) {
            log.error("ReportServiceImpl#uploadConvertPdf IO处理失败" + e);
            throw new BusinessException(StatusCode.FILE_HANDLE_EXCEPTION);
        }
        return true;
    }

    @Override
    public boolean webImgConvertPdf(HttpServletResponse response, List<String> imgList, int ratio, String paperSize) {
        response.reset();
        // 设置返回的请求ContentType
        response.setContentType(ContentTypeEnum.DOWNLOAD.getValue());
        // 设置返回的编码类型
        response.setCharacterEncoding(CharacterEncodingEnum.UTF_8.getCode());
        // 设置Content-disposition避免出现中文乱码
        response.setHeader(ResponseHeaderEnum.CONTENT_DISPOSITION.getCode(),
                ResponseHeaderEnum.CONTENT_DISPOSITION.getValue() + System.currentTimeMillis() + ".pdf");
        try {
            OutputStream ops = response.getOutputStream();
            //创建一个文档对象
            Document doc = new Document();
            //定义输出文件的位置
            PdfWriter.getInstance(doc, ops);
            doc.open();
            for (String webPath : imgList) {
                //默认A4大小
                if (StringUtils.isEmpty(paperSize) || PaperSizeEnum.A4.getSize().equals(paperSize)) {
                    byte[] imgByte = HttpUtil.downloadBytes(webPath);
                    DocumentUtil.docAddImg(doc, imgByte, ratio, PaperSizeEnum.A4.getWidth(), PaperSizeEnum.A4.getHeight());
                }
            }
            // 关闭文档
            doc.close();
            //输出给调用方
            ops.flush();
        } catch (DocumentException e) {
            log.error("ReportServiceImpl#webImgConvertPdf pdf文档生成失败" + e);
            throw new BusinessException(StatusCode.PDF_DOC_HANDLE_EXCEPTION);
        } catch (IOException e) {
            log.error("ReportServiceImpl#webImgConvertPdf IO处理失败" + e);
            throw new BusinessException(StatusCode.FILE_HANDLE_EXCEPTION);
        }
        return true;
    }

    private void flushLongImg(HttpServletResponse response, String imgType, int pageCount, PDFRenderer pdfRenderer, String fileName) {
        if (FileFormatEnum.PNG.getCode().equals(imgType)) {
            // 设置Content-disposition避免出现中文乱码
            response.setHeader(ResponseHeaderEnum.CONTENT_DISPOSITION.getCode(), ResponseHeaderEnum.CONTENT_DISPOSITION.getValue()
                    + fileName + "." + imgType);
        } else {
            // 设置Content-disposition避免出现中文乱码
            response.setHeader(ResponseHeaderEnum.CONTENT_DISPOSITION.getCode(), ResponseHeaderEnum.CONTENT_DISPOSITION.getValue()
                    + fileName + "." + FileFormatEnum.JPG.getCode());
        }
        int[][] imageArrays = new int[pageCount][];
        List<BufferedImage> images = new ArrayList<>(pageCount);
        int dstHeight = 0;
        int dstWidth = 0;
        try {
            for (int i = 0; i < pageCount; i++) {
                BufferedImage image = pdfRenderer.renderImageWithDPI(i, 200);
                images.add(image);
                int width = image.getWidth();
                int height = image.getHeight();

                // 从图片中读取RGB 像素
                imageArrays[i] = new int[width * height];
                imageArrays[i] = image.getRGB(0, 0, width, height, imageArrays[i], 0, width);
                // 计算合并的宽度和高度
                dstWidth = Math.max(dstWidth, width);
                dstHeight += height;
            }
            // 合成图片像素
            if (dstHeight < 1) {
                log.info("ReportServiceImpl#flushLongImg: dstHeight < 1");
            }
            // 生成新图片
            BufferedImage imageNew = new BufferedImage(dstWidth, dstHeight, BufferedImage.TYPE_INT_RGB);
            int heightTotal = 0;
            for (int i = 0; i < images.size(); i++) {
                int width = images.get(i).getWidth();
                int height = images.get(i).getHeight();
                imageNew.setRGB(0, heightTotal, width, height, imageArrays[i], 0, width);
                heightTotal += height;
            }
            ByteArrayOutputStream os = new ByteArrayOutputStream();
            ImageIO.write(imageNew, "jpg", os);
            InputStream input = new ByteArrayInputStream(os.toByteArray());
            BufferedInputStream bis = new BufferedInputStream(input);
            byte[] buff = new byte[1024];
            OutputStream ops = response.getOutputStream();
            int i;
            while (true) {
                i = bis.read(buff);
                if (i == -1) {
                    break;
                }
                ops.write(buff, 0, i);
                ops.flush();
            }
        } catch (IOException e) {
            log.error("ReportServiceImpl#flushLongImg IO处理失败" + e);
            throw new BusinessException(StatusCode.FILE_HANDLE_EXCEPTION);
        }
    }

    private String[] getSuffixAndFileName(MultipartFile file) {
        String originalFilename = file.getOriginalFilename();
        if (StringUtils.isBlank(originalFilename)) {
            throw new BusinessException(StatusCode.UPLOAD_FORMAT_NO_NAME);
        }
        int length = originalFilename.length();
//      文件后缀 带.
        String suffix = originalFilename.substring(length - 4);
        String fileName = originalFilename.substring(0, length - 4);
        return new String[]{suffix, fileName};
    }

    @Override
    public boolean uploadConvertImg(HttpServletResponse response, MultipartFile file, String imgType,
                                    boolean longFlag) {
//      文件后缀 带.
        String suffix = getSuffixAndFileName(file)[0];
//      文件格式 不带.
        String fileFormat = suffix.substring(1);
        String fileName = getSuffixAndFileName(file)[1];
        if (suffix.substring(0, 1).equals(FileFormatEnum.DOT.getCode()) && FileFormatEnum.PDF.getCode().equals(fileFormat)) {
            try {
                byte[] byteArr = file.getBytes();
                if (byteArr.length == 0) {
                    throw new BusinessException(StatusCode.UPLOAD_FORMAT_IS_EMPTY);
                }
                InputStream stream = new ByteArrayInputStream(byteArr);
                // 加载解析PDF文件
                PDDocument doc = PDDocument.load(stream);
                PDFRenderer pdfRenderer = new PDFRenderer(doc);
                PDPageTree pages = doc.getPages();
                int pageCount = pages.getCount();
                response.reset();
                // 设置返回的请求ContentType
                response.setContentType(ContentTypeEnum.DOWNLOAD.getValue());
                // 设置返回的编码类型
                response.setCharacterEncoding(CharacterEncodingEnum.UTF_8.getCode());
                //pdf只有一页的时候
                if (1 == pageCount) {
                    flushLongImg(response, imgType, pageCount, pdfRenderer, fileName);
                }
                //转长图
                else if (longFlag) {
                    flushLongImg(response, imgType, pageCount, pdfRenderer, fileName);
                }
                //转多张图片压缩到一个zip
                else {
                    flushZip(response, imgType, pageCount, pdfRenderer, fileName);
                    log.info("文件压缩完成");
                }
            } catch (IOException e) {
                log.error("ReportServiceImpl#uploadConvertImg IO处理失败" + e);
                throw new BusinessException(StatusCode.FILE_HANDLE_EXCEPTION);
            }
        } else {
            throw new BusinessException(StatusCode.INCORRECT_UPLOAD_FORMAT);
        }
        return true;
    }

    private void flushZip(HttpServletResponse response, String imgType, int pageCount, PDFRenderer
            pdfRenderer, String fileName) {
        // 设置Content-disposition避免出现中文乱码
        response.setHeader(ResponseHeaderEnum.CONTENT_DISPOSITION.getCode(), ResponseHeaderEnum.CONTENT_DISPOSITION.getValue() + fileName + ".zip");
        try {
            byte[] buf = new byte[1024];
            BufferedOutputStream bos = new BufferedOutputStream(response.getOutputStream());
            //文件或文件夹压缩流
            ZipOutputStream out = new ZipOutputStream(bos);
            for (int i = 0; i < pageCount; i++) {
                BufferedImage img = pdfRenderer.renderImageWithDPI(i, 200);
                ByteArrayOutputStream bs = new ByteArrayOutputStream();
                ImageOutputStream imOut = ImageIO.createImageOutputStream(bs);
                if (FileFormatEnum.PNG.getCode().equals(imgType)) {
                    ImageIO.write(img, imgType, imOut);
                } else {
                    ImageIO.write(img, FileFormatEnum.JPG.getCode(), imOut);
                }
                InputStream inputStream = new ByteArrayInputStream(bs.toByteArray());
                if (FileFormatEnum.PNG.getCode().equals(imgType)) {
                    out.putNextEntry(new ZipEntry(i + "." + imgType));
                } else {
                    out.putNextEntry(new ZipEntry(i + "." + FileFormatEnum.JPG.getCode()));
                }
                int len;
                while ((len = inputStream.read(buf)) != -1) {
                    out.write(buf, 0, len);
                }
            }
            out.closeEntry();
            out.close();
        } catch (IOException e) {
            log.error("ReportServiceImpl#flushZip IO处理失败" + e);
            throw new BusinessException(StatusCode.FILE_HANDLE_EXCEPTION);
        }
    }

}