进入下面小程序可以体验效果：

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

@Slf4j
public class App
{
    public static void main( String[] args ) throws IOException {
        byte[]bytes =  FileUtil.imageCompression("/xx/5645.jpg");
        FileOutputStream outputStream = new FileOutputStream("/xx/003.jpg");
        outputStream.write(bytes);
        outputStream.close();
    }
	
}

import lombok.extern.slf4j.Slf4j;
import net.coobird.thumbnailator.Thumbnails;
import net.coobird.thumbnailator.resizers.configurations.ScalingMode;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;

/**
 * @Author: Garcia
 * @CreateDate: 2019/12/10 15:52
 * @Description: what it is class?
 */
@Slf4j
public class FileUtil {

    /**
     * 压缩图片,默认80%
     */
    public static byte[] imageCompression(String path){
        ByteArrayOutputStream out = null;
        try {
            File file = new File(path);
            long length = file.length()/1024;
            if (length<100){
                byte[] fileByte = Files.readAllBytes(file.toPath());
                return fileByte;
            }
            double qual = 0.50;
            do {
                out = new ByteArrayOutputStream();
                Thumbnails.of(path).
                  scalingMode(ScalingMode.BICUBIC).
                  // 图片缩放90%, 不能和size()一起使用
                    scale(0.9).
                  // 图片质量压缩到50%
                    outputQuality(qual).
                  toOutputStream(out);
                qual=qual-0.1;
            }while ((out.size()/1024)>200);
            return out.toByteArray();
        } catch (IOException e) {
            log.error("图片压缩失败",e);
        }finally {
            if (out!=null){
                try {
                    out.close();
                } catch (IOException e) {
                    log.error("关闭流失败",e);
                }
            }
        }
        return null;
    }
}