如何使用Spring Web应用程序显示PDF文件

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.24</version>
</dependency>

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.springframework.core.io.ClassPathResource;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

@Controller
public class PdfController {

    @GetMapping(value = "/pdf/{filename}", produces = MediaType.IMAGE_JPEG_VALUE)
    public ResponseEntity<byte[]> displayPdf(@PathVariable String filename) throws IOException {
        ClassPathResource resource = new ClassPathResource("pdfs/" + filename + ".pdf");
        PDDocument document = PDDocument.load(resource.getInputStream());
        PDFRenderer renderer = new PDFRenderer(document);
        BufferedImage image = renderer.renderImage(0, 2.5f); // 渲染第一页为图像，缩放比例为2.5
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ImageIO.write(image, "jpeg", baos);
        baos.flush();
        byte[] imageData = baos.toByteArray();
        baos.close();
        document.close();
        return ResponseEntity.ok().body(imageData);
    }
}