Wispro-CodeWarehouse-BackEnd/PAS/src/main/java/cn/cslg/pas/service/patentPDF/PatentPDFService.java

package cn.cslg.pas.service.patentPDF;

import cn.cslg.pas.common.model.dto.PatentDTO;
import cn.cslg.pas.common.model.vo.PatentVO;
import cn.cslg.pas.common.utils.FileUtils;
import cn.cslg.pas.common.utils.StringUtils;
import cn.cslg.pas.domain.PatentInstruction;
import cn.cslg.pas.mapper.PatentInstructionMapper;
import cn.cslg.pas.service.PatentInstructionService;
import cn.cslg.pas.service.PatentService;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.apache.pdfbox.multipdf.PDFMergerUtility;
import org.apache.pdfbox.multipdf.Splitter;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.ImageType;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.springframework.stereotype.Service;

import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

/**
 * 查询专利的说明书pdf首页
 *
 * @author chenyu
 * @date 2023/9/6
 */
@RequiredArgsConstructor
@Slf4j
@Service
public class PatentPDFService extends ServiceImpl<PatentInstructionMapper, PatentInstruction> {
    private final PatentService patentService;
    private final FileUtils fileUtils;

    public void queryPatentPdfFirstPages(PatentVO params, HttpServletResponse response) throws IOException {
        log.info("开始处理【导出多件专利pdf首页】的业务，业务参数为：{}", params);

        //根据筛选条件，直接调用查询
        IPage<PatentDTO> pageList = patentService.getPageList(params);
        List<PatentDTO> patents = pageList.getRecords();
        List<String> patentNos = patents.stream().map(PatentDTO::getPatentNo).collect(Collectors.toList());

        //根据专利号patentNos查询出所有pdf文档数据
        List<PatentInstruction> patentInstructions = this.list(new LambdaQueryWrapper<PatentInstruction>().in(PatentInstruction::getPatentNo, patentNos).groupBy(PatentInstruction::getPatentNo));

        ArrayList<String> filePaths = new ArrayList<>();  //存放所有专利说明书首页pdf的文件路径
        for (PatentInstruction patentInstruction : patentInstructions) {  //遍历，将所有专利说明书pdf的首页取出生成新的Pdf文件存在本地
            String filePath = fileUtils.getSystemPath() + patentInstruction.getUrl();
            PDDocument doc = PDDocument.load(new File(filePath));
            Splitter splitter = new Splitter();
            splitter.setStartPage(1);
            splitter.setEndPage(1);
            PDDocument needDoc = splitter.split(doc).get(0);
            String newFilePath = "专利号" + patentInstruction.getPatentNo() + "的说明书pdf首页.pdf";
            needDoc.save(newFilePath);
            filePaths.add(newFilePath);
            needDoc.close();
            doc.close();
        }

        //开始合并上面生成的所有专利说明书首页pdf文件
        PDFMergerUtility pdfMerger = new PDFMergerUtility();
        for (String filePath : filePaths) {
            pdfMerger.addSource(filePath);
        }
        // 设置合并生成pdf文件名称
        String mergedFilePath = StringUtils.getUUID() + ".pdf";
        pdfMerger.setDestinationFileName(mergedFilePath);
        // 合并PDF
        pdfMerger.mergeDocuments();

        //最后要记得删除所有pdf首页临时文件
        for (String filePath : filePaths) {
            new File(filePath).delete();
        }

        InputStream fis = new BufferedInputStream(new FileInputStream(mergedFilePath));
        byte[] buffer = new byte[fis.available()];
        fis.read(buffer);
        fis.close();
        // 清空response
        response.reset();
        // 设置response的Header
        response.addHeader("Content-Disposition", "attachment;filename=" + new String(mergedFilePath.getBytes()));
        response.addHeader("Content-Length", "" + new File(mergedFilePath).length());
        OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
        response.setContentType("application/octet-stream");
        toClient.write(buffer);
        toClient.flush();
        toClient.close();

        //最后要记得删除合并后的pdf临时文件
        new File(mergedFilePath).delete();

    }

}