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图片压缩工具

package cn.swiftpass.spay.salesman.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Arrays;

/*
 * 图片压缩工具
 * */
public class ImgsUtils {
    protected static Logger logger = LoggerFactory.getLogger(ImgsUtils.class);


    public static byte[] compressUnderSize(byte[] srcImgData) throws IOException {
        return compressUnderSize(srcImgData, 1048576);
    }


    public static byte[] compressUnderSize(byte[] srcImgData, long maxSize) throws IOException {
        double scale = 0.9;
        byte[] imgData = Arrays.copyOf(srcImgData, srcImgData.length);
        logger.info("imgData.length {}", imgData.length);
        if (imgData.length > maxSize) {
            do {
                try {
                    imgData = compress(imgData, scale);
                } catch (IOException e) {
                    throw new IllegalStateException("压缩图片过程中出错，请及时联系管理员！", e);
                }

            } while (imgData.length > maxSize);
        }
        System.out.println(imgData.length);
        return imgData;
    }

    /**
     * 按照 宽高 比例压缩
     *
     * @param srcImgData 待压缩图片输入流
     * @param scale      压缩刻度
     * @return 压缩后图片数据
     * @throws IOException 压缩图片过程中出错
     */
    public static byte[] compress(byte[] srcImgData, double scale) throws IOException {
        BufferedImage bi = ImageIO.read(new ByteArrayInputStream(srcImgData));
        int width = (int) (bi.getWidth() * scale); // 源图宽度
        int height = (int) (bi.getHeight() * scale); // 源图高度

        Image image = bi.getScaledInstance(width, height, Image.SCALE_SMOOTH);
        BufferedImage tag = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        Graphics g = tag.getGraphics();
        g.setColor(Color.RED);
        g.drawImage(image, 0, 0, null); // 绘制处理后的图
        g.dispose();

        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        ImageIO.write(tag, "JPEG", bOut);

        return bOut.toByteArray();
    }

    /**
     * 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;
    }


    private static byte[] readInputStream(InputStream inStream) throws IOException {
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        //创建一个Buffer字符串
        byte[] buffer = new byte[1024];
        //每次读取的字符串长度，如果为-1，代表全部读取完毕
        int len = 0;
        //使用一个输入流从buffer里把数据读取出来
        while ((len = inStream.read(buffer)) != -1) {
            //用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度
            outStream.write(buffer, 0, len);
        }
        //关闭输入流
        inStream.close();
        //把outStream里的数据写入内存
        return outStream.toByteArray();
    }
    
    /**
     * 下载网络图并压缩
     * @param urlStr 网络图地址
     * @param newFile 新文件地址
     * @throws IOException
     */
    public static void downUrlImgAndCompressMax512(String urlStr,String newFile) throws IOException{
        //new一个URL对象
        URL url = null;
        url = new URL(urlStr);
        //打开链接
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        //设置请求方式为"GET"
        conn.setRequestMethod("GET");
        //超时响应时间为5秒
        conn.setConnectTimeout(5 * 1000);
        //通过输入流获取图片数据
        InputStream inStream = conn.getInputStream();
        //得到图片的二进制数据，以二进制封装得到数据，具有通用性
        byte[] data = readInputStream(inStream);
        byte[] bytes = compressUnderSize(data);
        //创建输出流
        FileOutputStream outStream = new FileOutputStream(newFile);
        //写入数据
        outStream.write(bytes);
        //关闭输出流
        outStream.close();

    }

    /**
     * 得到图片的二进制数据，以二进制封装得到数据，具有通用性
     * @param inStream
     * @return
     * @throws Exception
     */
    private static byte[] readInputStream(InputStream inStream) throws IOException{
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        //创建一个Buffer字符串
        byte[] buffer = new byte[1024];
        //每次读取的字符串长度，如果为-1，代表全部读取完毕
        int len = 0;
        //使用一个输入流从buffer里把数据读取出来
        while( (len=inStream.read(buffer)) != -1 ){
            //用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度
            outStream.write(buffer, 0, len);
        }
        //关闭输入流
        inStream.close();
        //把outStream里的数据写入内存
        return outStream.toByteArray();
    }


}

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