SpringBoot Image Processing with Thumbnailator, FastDFS, and Asynchronous Thread Pool

Environment

SpringBoot + FastDFS + Thumbnailator are used. The FastDFS environment must be set up separately.

Thumbnailator Dependency

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

Utility Class for Image Processing

import net.coobird.thumbnailator.Thumbnails;
import net.coobird.thumbnailator.geometry.Positions;
import org.springframework.stereotype.Component;
import javax.imageio.ImageIO;
import java.io.File;
import java.io.IOException;

@Component
public class PictureUtil {
    private static File markIco = null;
    static {
        try {
            markIco = new File(new File("").getCanonicalPath() + "/icon.png");
            LogUtil.info(PictureUtil.class, "Watermark image load " + (markIco.exists() ? "success" : "fail"));
        } catch (Exception e) {}
    }
    /** Add watermark */
    public void photoMark(File sourceFile, File toFile) throws IOException {
        Thumbnails.of(sourceFile)
            .size(600, 450)
            .watermark(Positions.BOTTOM_CENTER, ImageIO.read(markIco), 0.7f)
            .toFile(toFile);
    }
    /** Generate thumbnail */
    public void photoSmaller(File sourceFile, File toFile) throws IOException {
        Thumbnails.of(sourceFile)
            .size(200, 150)
            .outputQuality(0.4f)
            .toFile(toFile);
    }
    /** Generate video thumbnail (not used yet) */
    public void photoSmallerForVedio(File sourceFile, File toFile) throws IOException {
        Thumbnails.of(sourceFile)
            .size(440, 340)
            .watermark(Positions.BOTTOM_CENTER, ImageIO.read(markIco), 0.1f)
            .outputQuality(0.8f)
            .toFile(toFile);
    }
}

SpringBoot Thread Pool Configuration

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.task.TaskExecutor;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import java.util.concurrent.ThreadPoolExecutor;

@Configuration
@EnableAsync
public class PoolConfig {
    @Bean
    public TaskExecutor taskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.initialize();
        executor.setCorePoolSize(4);
        executor.setMaxPoolSize(32);
        executor.setQueueCapacity(512);
        executor.setKeepAliveSeconds(60);
        executor.setThreadNamePrefix("ThreadPool-");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.setWaitForTasksToCompleteOnShutdown(true);
        return executor;
    }
}

Key Async Notes

The controller class must be annotated with @EnableAsync .

The service method that should run asynchronously must be annotated with @Async .

Calls to an @Async method from within the same class will not be asynchronous; the call must come from another bean (e.g., controller → service).

Controller Endpoint for Image Upload

@ApiOperation("上传业务图片")
@PostMapping("/push/photo/{id}/{name}")
public R pushHousingPhotoMethod(@ApiParam("SourceId") @PathVariable Integer id,
                                @ApiParam("图片名称不约束，可不填则使用原名，可使用随机码或原名称，但必须带扩展名")
                                @PathVariable(required = false) String name,
                                @RequestParam MultipartFile file) throws InterruptedException, ExecutionException, IOException {
    String fileName = file.getOriginalFilename();
    String ext = StringUtils.substring(fileName, fileName.lastIndexOf('.'), fileName.length());
    File tempPhoto = File.createTempFile(UUIDUtil.make32BitUUID(), ext);
    file.transferTo(tempPhoto);
    service.pushPhoto(id, name, tempPhoto);
    return new R();
}

Utility for Generating 32‑Bit UUID

/** Generate a 32‑character UUID without hyphens */
public synchronized static String make32BitUUID() {
    return UUID.randomUUID().toString().replace("-", "");
}

Service Layer Implementation (Async)

@Async
public void pushHousingPhoto(Integer id, String name, File file) throws InterruptedException, ExecutionException, IOException {
    Long startTime = System.currentTimeMillis();
    Integer[] numb = fastDfsService.upLoadPhoto(StringUtils.isBlank(name) ? file.getName() : name, file).get();
    SourcePhotosContext context = new SourcePhotosContext();
    context.setSourceId(id);
    context.setNumber(numb[0]);
    context.setNumber2(numb[1]);
    sourcePhotosContextService.insertNew(context);
    Long endTime = System.currentTimeMillis();
    LogUtil.info(this.getClass(), "source [ " + id + " ] 绑定图片 [ " + name + " ] 成功,内部处理耗时 [" + (endTime - startTime) + "ms]");
}

FastDFS Service (Future‑based)

@Override
public Future
upLoadPhoto(String fileName, MultipartFile file) throws IOException {
    String ext = StringUtils.substring(fileName, fileName.lastIndexOf('.'));
    File sourcePhoto = File.createTempFile(UUIDUtil.make32BitUUID(), ext);
    file.transferTo(sourcePhoto);
    return upLoadPhoto(fileName, sourcePhoto);
}

@Override
public Future
upLoadPhoto(String fileName, File sourcePhoto) throws IOException {
    String ext = StringUtils.substring(fileName, fileName.lastIndexOf('.'));
    File markedPhoto = File.createTempFile(UUIDUtil.make32BitUUID(), ext);
    File smallerPhoto = File.createTempFile(UUIDUtil.make32BitUUID(), ext);
    pictureUtil.photoMark(sourcePhoto, markedPhoto);
    pictureUtil.photoSmaller(markedPhoto, smallerPhoto);
    Integer markedPhotoNumber = upLoadPhotoCtrl(fileName, markedPhoto);
    Integer smallerPhotoNumber = upLoadPhotoCtrl("mini_" + fileName, smallerPhoto);
    sourcePhoto.delete();
    markedPhoto.delete();
    smallerPhoto.delete();
    Integer[] res = new Integer[]{markedPhotoNumber, smallerPhotoNumber};
    return new AsyncResult(res);
}

The article also includes diagrams illustrating the upload flow and notes that the asynchronous approach avoids blocking the client while the server processes images.

Overall, the guide provides a practical, end‑to‑end solution for asynchronous image handling in a SpringBoot backend, covering dependencies, utility code, thread‑pool setup, controller/service design, and common pitfalls.