<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.24</version> <!-- 請(qǐng)檢查最新的版本 -->
</dependency>

package cn.iocoder.yudao.module.contract.service.content;
 
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.springframework.http.ResponseEntity;
 
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Base64;
import java.util.List;
 
public class PDFBoxUtil {
 
    /**
     * 加載 PDF 文檔
     */
    public static PDDocument loadPdf(byte[] input) throws IOException {
        return PDDocument.load(input);
    }
 
    /**
     * 添加印章到 PDF 文檔中
     *
     * @param document       PDF 文檔對(duì)象
     * @param imageByteArray 印章圖像的二進(jìn)制數(shù)據(jù)
     * @param x              橫坐標(biāo)
     * @param y              縱坐標(biāo)
     * @param h              高度
     * @param pageIdx        頁(yè)碼
     * @throws IOException 異常
     */
    public static void addStampToPdf(PDDocument document, byte[] imageByteArray, int x, int y, int h, int pageIdx) throws IOException {
        // 加載簽章圖像
        PDImageXObject pdImage = PDImageXObject.createFromByteArray(document, imageByteArray, "簽章");
 
        // 獲取 PDF 文檔的第一個(gè)頁(yè)面
        PDPage page = document.getPage(pageIdx);
 
        // 計(jì)算簽章圖像的尺寸
        float desiredHeight = h; // 目標(biāo)高度
        float scale = desiredHeight / pdImage.getHeight();
 
        // 創(chuàng)建一個(gè)內(nèi)容流以添加簽章
        try (PDPageContentStream contentStream = new PDPageContentStream(document, page, PDPageContentStream.AppendMode.APPEND, true, true)) {
            // 在 PDF 頁(yè)面上繪制簽章圖像
            contentStream.drawImage(pdImage, x, y, pdImage.getWidth() * scale, pdImage.getHeight() * scale);
        }
 
        // 可選：也可以向 PDF 添加一個(gè)簽名字段
//        addSignatureField(document);
    }
 
    /**
     * 將 BufferedImage 轉(zhuǎn)換為字節(jié)數(shù)組
     *
     * @param image 要轉(zhuǎn)換的圖像
     * @return 字節(jié)數(shù)組
     */
    private static byte[] imageToBytes(BufferedImage image) {
        try (ByteArrayOutputStream os = new ByteArrayOutputStream()) {
            ImageIO.write(image, "png", os);
            return os.toByteArray();
        } catch (IOException e) {
            throw new RuntimeException("Failed to convert image to bytes", e);
        }
    }
 
    /**
     * 裁剪圖像
     *
     * @param image 要裁剪的圖像
     * @param page PDF 頁(yè)面
     * @param x 開(kāi)始裁剪的橫坐標(biāo)
     * @param y 開(kāi)始裁剪的縱坐標(biāo)
     * @param w 需要裁剪的寬度
     * @param h 需要裁剪的高度
     * @return 裁剪后的圖片
     */
    private static BufferedImage cropImage(BufferedImage image, PDPage page, int x, int y, int w, int h) {
        PDRectangle mediaBox = PDRectangle.A4; // 使用默認(rèn)的 A4 大小
 
        // 將 PDF 單位轉(zhuǎn)換為圖像坐標(biāo)
        int width = (int) (mediaBox.getWidth() * (image.getWidth() / page.getMediaBox().getWidth()));
        int height = (int) (mediaBox.getHeight() * (image.getHeight() / page.getMediaBox().getHeight()));
 
        // 裁剪圖像
        return image.getSubimage(x, y, width - w, height - h);
    }
    
    /**
     * 將 PDF 轉(zhuǎn)換為多個(gè)圖片
     *
     * @param pdfBytes PDF 二進(jìn)制數(shù)據(jù)
     * @param dpi      DPI 值
     * @return 裁剪后的圖片列表
     * @throws IOException 異常
     */
    public static List<byte[]> convertPdfToImages(byte[] pdfBytes, int numberOfPages, int dpi, int x, int y, int w, int h) throws IOException {
        List<byte[]> croppedImages = new ArrayList<>();
        try (PDDocument document = PDDocument.load(new ByteArrayInputStream(pdfBytes))) {
            PDFRenderer renderer = new PDFRenderer(document);
            if (numberOfPages == 0) {
                numberOfPages = document.getNumberOfPages();
            }
 
            for (int i = 0; i < numberOfPages; i++) {
                // 渲染頁(yè)面
                BufferedImage image = renderer.renderImageWithDPI(i, dpi); // 300 DPI
                // 裁剪圖像
                BufferedImage croppedImage = cropImage(image, document.getPage(i), x, y, w, h);
                byte[] croppedImageBytes = imageToBytes(croppedImage);
                croppedImages.add(croppedImageBytes);
            }
        }
        return croppedImages;
    }
 
    /**
     * 將 PDF 轉(zhuǎn)換為 Base64 編碼的 JSON
     *
     * @param fileContent PDF 二進(jìn)制數(shù)據(jù)
     * @param x 開(kāi)始裁剪的橫坐標(biāo)
     * @param y 開(kāi)始裁剪的縱坐標(biāo)
     * @param w 需要裁剪的寬度
     * @param h 需要裁剪的高度
     * @return Base64 編碼的 JSON
     * @throws Exception 異常
     */
    public static ResponseEntity<String> convertPdfToBase64(byte[] fileContent, int x, int y, int w, int h) throws Exception {
        List<byte[]> imageBytesList = convertPdfToImages(fileContent, 0, 300, x, y, w, h);
 
        List<String> base64Images = new ArrayList<>();
        for (byte[] imageBytes : imageBytesList) {
            String base64Image = Base64.getEncoder().encodeToString(imageBytes);
            base64Images.add(base64Image);
        }
        ObjectMapper mapper = new ObjectMapper();
        String jsonResult = mapper.writeValueAsString(base64Images);
        return ResponseEntity.ok().body(jsonResult);
    }
}

/**
     * 測(cè)試添加數(shù)字簽名
     *
     * @param filename 文件名
     * @param x x坐標(biāo)
     * @param y y坐標(biāo)
     * @param h 高度
     * @param i 寬度
     */
    @GetMapping("/stamp/{filename}/p")
    @Parameter(name = "x", description = "添加簽名的 x 坐標(biāo)", required = true, example = "x")
    @Parameter(name = "y", description = "添加簽名的 y 坐標(biāo)", required = true, example = "y")
    @Parameter(name = "h", description = "簽名的顯示高度", required = true, example = "h")
    @Parameter(name = "i", description = "簽名所在頁(yè)數(shù)下標(biāo)", required = true, example = "i")
    public ResponseEntity<ByteArrayResource> stampTest(@PathVariable String filename, @RequestParam("x") Integer x, @RequestParam("y") Integer y,
                                                    @RequestParam("h") Integer h, @RequestParam("i") Integer i) throws Exception {
        // 從數(shù)據(jù)庫(kù)中獲取文件內(nèi)容,這里需要修改為你們自己的獲取方式來(lái)獲取源 PDF 文件的字節(jié)數(shù)組
        byte[] fileContent = fileApi.getFileContent(4L, filename);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
 
        // 添加數(shù)字簽名
        try (PDDocument document = PDFBoxUtil.loadPdf(fileContent)) {
            // 這里需要修改為你們自己的獲取方式來(lái)獲取簽名文件的字節(jié)數(shù)組
            byte[] imageByteArray = fileApi.getFileContent(4L, "2c095928083c5ee82e6e229089892191d7790a3a42616dfd5a49daae68c27f41.png");
            PDFBoxUtil.addStampToPdf(document, imageByteArray, x, y, h, i);
            document.save(out);
        } catch (IOException e) {
            e.printStackTrace();
        }
 
        // 創(chuàng)建 ByteArrayResource
        ByteArrayResource resource = new ByteArrayResource(out.toByteArray());
 
        return ResponseEntity.ok()
                .header(HttpHeaders.CONTENT_DISPOSITION, "inline; filename=\"" + filename + "\"")
                .contentType(MediaType.APPLICATION_PDF)
                .body(resource);
    }

/**
     * 根據(jù)合約名稱獲取合約 PDF 文件，并返回圖片的 Base64 編碼
     *
     * @param filename合約標(biāo)識(shí)
     * @return 圖片的 Base64 編碼
     */
    @GetMapping(value = "/get/{filename}", produces = MediaType.IMAGE_PNG_VALUE)
    @Parameter(name = "x", description = "每一頁(yè)開(kāi)始裁剪的 x 橫坐標(biāo)", required = true, example = "x")
    @Parameter(name = "y", description = "每一頁(yè)開(kāi)始裁剪的 y 縱坐標(biāo)", required = true, example = "y")
    @Parameter(name = "h", description = "每一頁(yè)需要裁剪掉的高度 h", required = true, example = "h")
    @Parameter(name = "w", description = "每一個(gè)需要裁剪掉的寬度 w", required = true, example = "w")
    public ResponseEntity<String> getPageImage(@PathVariable String filename, @RequestParam("x") int x, @RequestParam("y") int y,
                                                            @RequestParam("h") int h, @RequestParam("w") int w) {
        
        // 從數(shù)據(jù)庫(kù)中獲取文件內(nèi)容,這里需要修改為你們自己的獲取方式來(lái)獲取源 PDF 文件的字節(jié)數(shù)組
        byte[] fileContent = fileApi.getFileContent(4L, filename);
        
        try {
            return PDFBoxUtil.convertPdfToBase64(fileContent, x, y, w, h);
        } catch (IOException e) {
            throw new RuntimeException("獲取 PDF 文件截圖異常", e);
        } catch (Exception e) {
            throw new RuntimeException("讀取 PDF 文件異常", e);
        }
    }

<template>
  <Dialog :title="dialogTitle" v-model="dialogVisible">
    <div v-if="formLoading">{{message}}</div>
    <div id="pdf-container">
    </div>
  </Dialog>
</template>
<script setup lang="ts">
 
defineOptions({ name: 'ContentWXPreview' })
 
const dialogVisible = ref(false) // 彈窗的是否展示
const dialogTitle = ref('') // 彈窗的標(biāo)題
const formLoading = ref(false) // 表單的加載中
const message = ref('數(shù)據(jù)正在加載請(qǐng)稍后 ... ...')
 
/** 打開(kāi)彈窗 */
const open = async (title: string, code: string) => {
  dialogVisible.value = true
  dialogTitle.value = title + '_預(yù)覽'
  formLoading.value = true
  try {
    fetch('http://IP:端口/你們自己的控制器前綴/stamp/文件名/p?x=250&y=188&w=520&h=385', {
        method: 'GET',
        headers: {
            'Content-Type': 'application/octet-stream'
        }
    })
    .then(response => response.text())
    .then(base64Images => {
        const container = document.getElementById('pdf-container')
        if (container) {
          container.innerHTML = '' // 清空容器
 
          const images = JSON.parse(base64Images)
          images.forEach(base64Image => {
              let img = document.createElement('img')
              img.src = `data:image/png;base64,${base64Image}`
              container.appendChild(img)
          })
        }
        formLoading.value = false
    })
  } finally {
    formLoading.value = false
  }
}
defineExpose({ open }) // 提供 open 方法，用于打開(kāi)彈窗
</script>
 
<style lang="scss">
#pdf-container {
  display: flex;
  flex-direction: column;
  align-items: center;
}
 
#pdf-container > img {
  max-width: 100%; 
}
</style>