Java 圖片上傳壓縮實戰：基於 Thumbnailator 的高效實現方案

Thumbnailator 簡介

Thumbnailator 是 Google 開源的 Java 圖片處理庫，API 設計極簡，兩三行代碼即可完成縮放、裁剪、水印、旋轉等操作，處理效果優於原生 Java API，且持續維護更新。

核心優勢

• 支持縮放、區域裁剪、水印、旋轉、保持比例
• 批量處理目錄下所有圖片
• 鏈式 API，代碼量極少
• 活躍維護，生產環境可靠

Maven 依賴

<dependency>
    <groupId>net.coobird</groupId>
    <artifactId>thumbnailator</artifactId>
    <version>0.4.8</version>
</dependency>

常用操作範例

指定尺寸縮放（保持比例）

// 縮放至 400x500 範圍內，保持原圖比例
Thumbnails.of(fromPic).size(400, 500).toFile(toPic);

按比例縮放

// 縮小至 20%
Thumbnails.of(fromPic).scale(0.2f).toFile(toPic);
// 放大至 200%
Thumbnails.of(fromPic).scale(2f).toFile(toPic);

不變尺寸壓縮文件大小

// 品質參數 0.25f（1.0 為最高品質）
Thumbnails.of(fromPic).scale(1f).outputQuality(0.25f).toFile(toPic);

完整上傳壓縮實現代碼

/**
 * 上傳圖片並生成縮略圖
 * @param imageFile 上傳文件
 * @param request 請求對象
 * @param uploadPath 上傳目錄
 * @return 處理結果
 */
public static BaseResult uploadFileAndCreateThumbnail(MultipartFile imageFile,
        HttpServletRequest request, String uploadPath) {
    
    // 參數校驗
    if (imageFile == null) {
        return new BaseResult(false, "imageFile不能為空");
    }
    if (imageFile.getSize() >= 10 * 1024 * 1024) {
        return new BaseResult(false, "文件不能大於10M");
    }

    // 生成唯一文件名
    String uuid = UUID.randomUUID().toString();
    String dateDir = CommonDateUtils.date2string(new Date(), CommonDateUtils.YYYY_MM_DD);
    String ext = FilenameUtils.getExtension(imageFile.getOriginalFilename());
    String pathName = dateDir + File.separator + uuid + "." + ext;

    // 構建服務器絕對路徑
    String realPath = request.getServletContext().getRealPath(uploadPath);
    String filePathName = realPath + File.separator + pathName;

    // 確保目錄存在
    File file = new File(filePathName);
    if (!file.getParentFile().exists()) {
        file.getParentFile().mkdirs();
    }

    // 寫入原圖
    try (InputStream inputStream = imageFile.getInputStream();
         FileOutputStream fileOutputStream = new FileOutputStream(file)) {
        
        byte[] buffer = new byte[2048];
        IOUtils.copyLarge(inputStream, fileOutputStream, buffer);
    } catch (IOException e) {
        return new BaseResult(false, "操作失敗", e.getMessage());
    }

    // 生成縮略圖邏輯
    String thumbnailPathName = dateDir + File.separator + uuid + "small." + ext;
    if (thumbnailPathName.contains(".png")) {
        thumbnailPathName = thumbnailPathName.replace(".png", ".jpg");
    }

    long size = imageFile.getSize();
    double scale = 1.0;
    if (size >= 200 * 1024) {
        scale = (200 * 1024f) / size;
    }

    String thumbnailFilePathName = realPath + File.separator + thumbnailPathName;
    try {
        if (size < 200 * 1024) {
            // 小文件僅轉格式
            Thumbnails.of(filePathName).scale(1f).outputFormat("jpg").toFile(thumbnailFilePathName);
        } else {
            // 大文件壓縮品質
            Thumbnails.of(filePathName)
                .scale(1f)
                .outputQuality(scale)
                .outputFormat("jpg")
                .toFile(thumbnailFilePathName);
        }
    } catch (Exception e) {
        return new BaseResult(false, "操作失敗", e.getMessage());
    }

    // 返回結果
    Map<String, Object> result = new HashMap<>();
    result.put("originalUrl", pathName);
    result.put("thumbnailUrl", thumbnailPathName);
    return new BaseResult(true, "操作成功", result);
}

配置文件讀取工具類

public class PropertiesUtil {
    private static final PropertiesUtil INSTANCE = new PropertiesUtil();
    private final ConcurrentHashMap<String, Properties> cache = new ConcurrentHashMap<>();
    private final Logger logger = LoggerFactory.getLogger(PropertiesUtil.class);

    private PropertiesUtil() {}

    public static PropertiesUtil getInstance() {
        return INSTANCE;
    }

    public String getSysPro(String key) {
        return getSysPro(key, null);
    }

    public String getSysPro(String key, String defaultValue) {
        String profile = System.getProperty("spring.profiles.active");
        String fileName = "spring/imageserver-" + profile + ".properties";
        return getValue(fileName, key, defaultValue);
    }

    private String getValue(String fileName, String key, String defaultValue) {
        Properties props = cache.get(fileName);
        if (props == null) {
            try (InputStream is = PropertiesUtil.class.getClassLoader().getResourceAsStream(fileName)) {
                if (is != null) {
                    props = new Properties();
                    props.load(new InputStreamReader(is, "UTF-8"));
                    cache.put(fileName, props);
                }
            } catch (IOException e) {
                logger.error("載入配置失敗: {}", fileName, e);
            }
        }
        return props != null ? props.getProperty(key, defaultValue) : defaultValue;
    }
}

使用示例

// 獲取上傳路徑配置
String uploadPath = PropertiesUtil.getInstance().getSysPro("uploadPath");