springboot 中用 pdfbox 将pdf分片

首先pom.xml

dependency>
            org.apache.pdfbox
            pdfbox
            2.0.24

其余代码慢慢参考

package com.example.springboot04data.controller;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.hutool.core.io.FileUtil;
import cn.hutool.core.io.IoUtil;
import cn.hutool.core.io.file.FileReader;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
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.rendering.PDFRenderer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;



@Slf4j
//@Controller
//@RequestMapping("/api/file")
public class FileController {
    public static final Logger logger = LoggerFactory.getLogger(FileController.class);

    
    @RequestMapping(value = "/showpdf", method = RequestMethod.GET)
    public void showpdf(HttpServletRequest req, HttpServletResponse res) {
        try {
            this.download(req, res);
        } catch (Exception e) {
            // e.printStackTrace();
            logger.error("错误信息:{}", e.getMessage(), e);
        }
    }

    @RequestMapping(value = "/showpdf2", method = RequestMethod.GET)
    public void showpdf2(HttpServletRequest req, HttpServletResponse res) {
        try {
            String filePdf = "D:/test.pdf";
            byte[] zByte = FileUtil.readBytes(filePdf);
            log.info("总长度: " + zByte.length);
            BufferedInputStream in = FileUtil.getInputStream(filePdf);
            int offset = 0;
            int size = 1024 * 1024;
            byte[] bytes = new byte[size];
            in.read(bytes, offset, size);
            res.getOutputStream().write(bytes);
            res.getOutputStream().flush();
            in.close();
        } catch (Exception e) {
            // e.printStackTrace();
            logger.error("错误信息:{}", e.getMessage(), e);
        }
    }


    

    public void download(HttpServletRequest request, HttpServletResponse response) throws IOException {
        int pageIndex = Integer.valueOf(request.getParameter("pageIndex"));  //
        int pageSize = Integer.valueOf(request.getParameter("pageSize"));  //
        // 下载的字节范围
        int startPage = (pageIndex - 1) * pageSize + 1;
        int endPage = startPage + pageSize - 1;
        // startPage
        PDdocument document = null;
        PDdocument documentDown = null;
        OutputStream os = null;
        BufferedOutputStream bos = null;

        try {
            os = response.getOutputStream();
            bos = new BufferedOutputStream(os);
            // 返回http状态
            response.setStatus(206);
            // 需要下载字节数
            String filePdf = "D:/test.pdf";
            List fileList = new ArrayList();
            for (int i = startPage; i <= endPage; i++) {
                String pageFile = String.format("D:/test-%d.pdf", i);
                PdfFile pdfFile = new PdfFile();
                pdfFile.setPage(i);
                pdfFile.setFile(new File(pageFile));
                fileList.add(pdfFile);
            }
            //  int countPage = startPage;
            List pdfList = new ArrayList<>();
            //循环文件数组，来判断它们是否已经分片
            for (int k = 0; k < fileList.size(); k++) {
                PdfFile fileTemp = fileList.get(k);
                if (fileTemp.exists()) {
                    // documentDown = PDdocument.load(fileTemp);
                    pdfList.add(PDdocument.load(fileTemp.getFile()));
                    log.info("直接加载分页Pdf: 第 " + fileTemp.getPage() + "页");
                } else {
//                    if (startPage == 0) {// ???没懂
//                        documentDown = PDdocument.load(new File(filePdf));//解析PDF
//                    } else { }

                    log.info("加载完整Pdf: 第 " + fileTemp.getPage() + "页, 并生成分页Pdf");
                    // 从文件存储服务器下载文件到本地
                    if (document == null) {
                        document = PDdocument.load(new File(filePdf));
                    }
                    Splitter splitter = new Splitter();//将一个文档拆分为多个其他文档。
                    splitter.setStartPage(fileTemp.getPage());
                    splitter.setEndPage(fileTemp.getPage());
                    //将整个文档分页
                    List pages = splitter.split(document);
                    for (int i = 0; i < pages.size(); i++) {
                        pdfList.add(pages.get(i));
                        //documentDown = pages.get(i);
                        pages.get(i).save(fileTemp.getFile());
                        //  countPage += 1;
                        break;
                    }
                }
            }
            //关闭流
//            if (documentDown != null) {
            //     documentDown.save(bos);
//                documentDown.close();
//            }
            PDdocument documentMerger = new PDdocument();
            PDFMergerUtility PDFmerger = new PDFMergerUtility();
            for (PDdocument addDoc : pdfList) {
                PDFmerger.appenddocument(documentMerger, addDoc);
            }
            documentMerger.save(bos);
            documentMerger.close();
            for (PDdocument addDoc : pdfList) {
                addDoc.close();
            }
            // log.info("pageCount: " + document.getNumberOfPages());
        } catch (IOException e) {
            System.out.println("下载中断!");
            logger.error("错误信息:{}", e.getMessage(), e);
        } finally {
            if (document != null) {
                document.close();
            }
            if (documentDown != null) {
                documentDown.close();
            }
            bos.close();
            os.flush();
            os.close();
        }
    }

    @Data
    public class PdfFile {
        private File file;
        private int page;

        public boolean exists() {
            return file != null && file.exists() ? true : false;
        }
    }
}