java-insagent-pc/src/main/java/com/ydtech/utils/ImageCompressionUtils.java

package com.ydtech.utils;

import com.ydtech.exception.SystemException;
import lombok.extern.slf4j.Slf4j;
import net.coobird.thumbnailator.Thumbnails;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.nio.file.Files;

/**
 * @author wenks
 * @version 0.0.2
 * @description 文件压缩工具类
 * @date 2023/4/11 10:27
 */
@Slf4j
public class ImageCompressionUtils {

    private ImageCompressionUtils() {
        throw new IllegalStateException("Utility class");
    }

    private static final Integer ZERO = 0;
    private static final Integer ONE_ZERO_TWO_FOUR = 1024;
    private static final Integer NINE_ZERO_ZERO = 900;
    private static final Integer THREE_TWO_SEVEN_FIVE = 3275;
    private static final Integer TWO_ZERO_FOUR_SEVEN = 2047;
    private static final Double ZERO_EIGHT_FIVE = 0.85;
    private static final Double ZERO_SIX = 0.6;
    private static final Double ZERO_FOUR_FOUR = 0.44;
    private static final Double ZERO_FOUR = 0.4;

    /**
     * 压缩大小不变
     *
     * @param inputStream 输入流
     * @param suffix      文件后缀名
     * @param path        路劲
     * @return 字节
     */
    public static byte[] compressPic(InputStream inputStream, String suffix, String path) throws IOException {
        File temp = File.createTempFile("temp", suffix, new File(path));
        try (FileOutputStream os = new FileOutputStream(temp);) {
            BufferedImage image = ImageIO.read(inputStream);
            int width = image.getWidth();
            int height = image.getHeight();
            BufferedImage bfImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            bfImage.getGraphics().drawImage(image.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);
            ImageIO.write(bfImage, suffix.replace(".", ""), os);
        } catch (IOException e) {
            e.printStackTrace();
        }
        byte[] bytesByFile = getBytesByFile(temp);
        Files.delete(temp.getAbsoluteFile().toPath());
        return bytesByFile;
    }

    /**
     * 文件转字节
     *
     * @param file 文件
     * @return 字节
     */
    public static byte[] getBytesByFile(File file) {
        try (FileInputStream fis = new FileInputStream(file); ByteArrayOutputStream bos = new ByteArrayOutputStream(1000)) {
            byte[] b = new byte[1000];
            int n;
            while ((n = fis.read(b)) != -1) {
                bos.write(b, 0, n);
            }
            return bos.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return new byte[0];
    }

    /**
     * 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
     * @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 <= ZERO || imageBytes.length < desFileSize * ONE_ZERO_TWO_FOUR) {
            return imageBytes;
        }
        long srcSize = imageBytes.length;
        double accuracy = getAccuracy(srcSize / ONE_ZERO_TWO_FOUR);
        try {
            while (imageBytes.length > desFileSize * ONE_ZERO_TWO_FOUR) {
                ByteArrayInputStream inputStream = new ByteArrayInputStream(imageBytes);
                ByteArrayOutputStream outputStream = new ByteArrayOutputStream(imageBytes.length);
                Thumbnails.of(inputStream)
                        .scale(accuracy)
                        .outputQuality(accuracy)
                        .toOutputStream(outputStream);
                imageBytes = outputStream.toByteArray();
            }
            log.info("图片原大小={}kb | 压缩后大小={}kb",
                    srcSize / ONE_ZERO_TWO_FOUR, imageBytes.length / ONE_ZERO_TWO_FOUR);
        } catch (Exception e) {
            log.error("【图片压缩】msg=图片压缩失败!", e);
            throw new SystemException(e.toString());
        }
        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 < NINE_ZERO_ZERO) {
            accuracy = ZERO_EIGHT_FIVE;
        } else if (size < TWO_ZERO_FOUR_SEVEN) {
            accuracy = ZERO_SIX;
        } else if (size < THREE_TWO_SEVEN_FIVE) {
            accuracy = ZERO_FOUR_FOUR;
        } else {
            accuracy = ZERO_FOUR;
        }
        return accuracy;
    }

}