基于SpringBoot实现图片上传并生成缩略图功能

<!-- Spring Boot Web -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
 
<!-- 文件上传 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>
 
<!-- 图片处理依赖 -->
<dependency>
    <groupId>com.twelvemonkeys.imageio</groupId>
    <artifactId>imageio-core</artifactId>
    <version>3.8.1</version>
</dependency>
 
<!-- Apache Commons IO -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.8.0</version>
</dependency>

import org.springframework.web.multipart.MultipartFile;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.*;
 
public String uploadPictureThumbnail(String bucketName, MultipartFile multipartFile, Long assocId, String originalStorageName, Integer scale, Integer width, Integer height) {
    String directoryPath = "";
    if (OsUtils.isLinux()) {
        directoryPath = "/tempdir";
    } else if (OsUtils.isWindows()) {
        directoryPath = "C:/tempdir";
    }
 
    File directory = new File(directoryPath);
    if (!directory.exists()) {
        directory.mkdir();
    }
 
    String originalName = multipartFile.getOriginalFilename();
    String suffixName = getSuffixName(originalName, ".", 0);
    String suffix = getSuffixName(originalName, ".", 1);
    String storageName = UUID.randomUUID().toString() + suffixName;
    String storageFileName = null;
 
    List<String> thumbnailSuffixName = Arrays.asList(".png", ".jpg", ".jpeg", ".gif");
    if (thumbnailSuffixName.contains(suffixName.toLowerCase())) {
        try {
            // 保存原始图片
            String originalImagePath = directoryPath + "/" + storageName;
            Path filePath = Paths.get(originalImagePath);
            Files.write(filePath, multipartFile.getBytes());
 
            // 读取原始图片并生成缩略图
            BufferedImage originalImage = ImageIO.read(new File(originalImagePath));
            int originalWidth = originalImage.getWidth();
            int originalHeight = originalImage.getHeight();
 
            // 计算缩略图尺寸
            int[] data = computeSize(originalWidth, originalHeight, scale, width, height);
            int thumbnailWidth = data[0];
            int thumbnailHeight = data[1];
 
            Image scaledImage = originalImage.getScaledInstance(thumbnailWidth, thumbnailHeight, Image.SCALE_SMOOTH);
            BufferedImage thumbnailImage = new BufferedImage(thumbnailWidth, thumbnailHeight, BufferedImage.TYPE_INT_RGB);
            Graphics2D g2d = thumbnailImage.createGraphics();
            g2d.drawImage(scaledImage, 0, 0, null);
            g2d.dispose();
 
            // 保存缩略图
            String thumbnailPath = directoryPath + "/" + UUID.randomUUID().toString() + suffixName;
            File thumbnailFile = new File(thumbnailPath);
            ImageIO.write(thumbnailImage, suffix.replace(".", ""), thumbnailFile);
 
            // 上传缩略图（这里用自定义 uploadFile 方法上传到对象存储）
            try (FileInputStream in = new FileInputStream(thumbnailFile)) {
                String name = getSuffixName(originalStorageName, "/", 1);
                storageFileName = uploadFile(bucketName, in, multipartFile.getContentType(), assocId, thumbnailFile.length(), name, "thumbnail");
            }
 
            // 清理临时文件
            new File(originalImagePath).delete();
            thumbnailFile.delete();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return storageFileName;
}

private int[] computeSize(int originalWidth, int originalHeight, Integer scale, Integer width, Integer height) {
    if (scale != null && scale > 0) {
        return new int[]{originalWidth * scale / 100, originalHeight * scale / 100};
    } else if (width != null && height != null) {
        return new int[]{width, height};
    } else {
        // 默认缩小为原始尺寸的 50%
        return new int[]{originalWidth / 2, originalHeight / 2};
    }
}