图片压缩工具，记录一下。

代码：

import net.coobird.thumbnailator.Thumbnails;
import org.apache.commons.io.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;

/**
 * 图片压缩Utils*/
public class PicUtils {

    private static Logger logger = LoggerFactory.getLogger(PicUtils.class);

    /*public static void main(String[] args) throws IOException {
        byte[] bytes = FileUtils.readFileToByteArray(new File("D:\test\371386015451197440.jpg"));
        long l = System.currentTimeMillis();
        bytes = PicUtils.compressPicForScale(bytes, 300, "x");// 图片小于300kb
        System.out.println(System.currentTimeMillis() - l + "毫秒");
        FileUtils.writeByteArrayToFile(new File("D:\test\dd1.jpg"), bytes);
    }
*/
    /**
     * 根据指定大小压缩图片
     *
     * @param imageBytes  源图片字节数组
     * @param desFileSize 指定图片大小，单位kb
     * @param imageId     影像编号
     * @return 压缩质量后的图片字节数组
     */
    public static byte[] compressPicForScale(byte[] imageBytes, long desFileSize) {
        if (imageBytes == null || imageBytes.length <= 0 || imageBytes.length < desFileSize * 1024) {
            return imageBytes;
        }
        long srcSize = imageBytes.length;
        double accuracy = getAccuracy(srcSize / 1024);
        try {
            while (imageBytes.length > desFileSize * 1024) {
                ByteArrayInputStream inputStream = new ByteArrayInputStream(imageBytes);
                ByteArrayOutputStream outputStream = new ByteArrayOutputStream(imageBytes.length);
                Thumbnails.of(inputStream)
                        .scale(accuracy)
                        .outputQuality(accuracy)
                        .toOutputStream(outputStream);
                imageBytes = outputStream.toByteArray();
            }
            logger.info("【图片压缩】imageId={} | 图片原大小={}kb | 压缩后大小={}kb",
                     srcSize / 1024, imageBytes.length / 1024);
        } catch (Exception e) {
            logger.error("【图片压缩】msg=图片压缩失败!", e);
        }
        return imageBytes;
    }

    /**
     * 自动调节精度(经验数值)
     *
     * @param size 源图片大小
     * @return 图片压缩质量比
     */
    private static double getAccuracy(long size) {
        double accuracy;
        if (size < 900) {
            accuracy = 0.85;
        } else if (size < 2047) {
            accuracy = 0.6;
        } else if (size < 3275) {
            accuracy = 0.44;
        } else {
            accuracy = 0.4;
        }
        return accuracy;
    }

}

调用：

@Override
    public byte[] downloadHuawei(String imagePath) throws IOException{
        byte[] img = InputStream2ByteArray(imagePath);
        return PicUtils.compressPicForScale(img, 300);// 图片小于300kb
    }

    public byte[] InputStream2ByteArray(String filePath) throws IOException {
        InputStream in = new FileInputStream(filePath);
        byte[] data = toByteArray(in);
        in.close();
        return data;
    }