ImageUtil图片工具: 压缩/格式转换等

import net.coobird.thumbnailator.Thumbnails;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import sun.misc.BASE64Encoder;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * Created by niewj on 2018/9/10.
 */
public class ImgUtil {// @TODO

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

    public static final String JPG = "jpg";
    public static final String GIF = "gif";
    public static final String PNG = "png";
    public static final String BMP = "bmp";
    public static final int K = 1024;

    public static final String TYPE_UNKNOWN = "unknown";

    /**
     * png格式图片转为jpg格式
     *
     * @param pngFile
     * @return
     */
    public static File convert2Jpg(File pngFile) {
        // #0. 判空
        if (pngFile == null || !pngFile.exists() || !pngFile.isFile() || !pngFile.canRead()) {
            return null;
        }

        File jpgFile = null;
        BufferedImage image;

        try {
            //#1. read image file
            image = ImageIO.read(pngFile);
            String parentPath = pngFile.getParent();

            logger.info(ImgUtil.getPicType(new FileInputStream(pngFile)));

            // #2. create a blank, RGB, same width and height, and a white background
            BufferedImage newBufferedImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
            newBufferedImage.createGraphics().drawImage(image, 0, 0, Color.WHITE, null);

            // #3. create image filename
            long currentMillis = System.currentTimeMillis();
            jpgFile = new File(parentPath, currentMillis + ".jpg");

            // write to jpeg file
            ImageIO.write(newBufferedImage, "jpg", jpgFile);

            logger.info("Done");

        } catch (IOException e) {

            e.printStackTrace();

        }

        return jpgFile;
    }

    /**
     * 旋转图片
     *
     * @param sourceFile 原图片
     * @param degrees     旋转度数
     * @throws IOException
     */
    public static void rotate(File sourceFile, double degrees) throws IOException {
        Thumbnails.of(sourceFile)
                .rotate(degrees)//旋转度数
                .scale(1)//缩放比例
                .toFile(sourceFile);
    }

    /**
     * 根据文件流判断图片类型
     *
     * @param fis
     * @return jpg/png/gif/bmp
     */
    public static String getPicType(FileInputStream fis) {
        //读取文件的前几个字节来判断图片格式
        byte[] b = new byte[4];
        try {
            fis.read(b, 0, b.length);
            String type = bytesToHexString(b).toUpperCase();
            if (type.contains("FFD8FF")) {
                return JPG;
            } else if (type.contains("89504E47")) {
                return PNG;
            } else if (type.contains("47494638")) {
                return GIF;
            } else if (type.contains("424D")) {
                return BMP;
            } else {
                return TYPE_UNKNOWN;
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }

    /**
     * byte数组转换成16进制字符串
     *
     * @param src
     * @return
     */
    private static String bytesToHexString(byte[] src) {
        StringBuilder sBuilder = new StringBuilder();
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 0; i < src.length; i++) {
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                sBuilder.append(0);
            }
            sBuilder.append(hv);
        }
        return sBuilder.toString();
    }

    /**
     * @param srcFile     待压缩的源文件
     * @param desFileSize 限制的文件大小，单位Kb
     * @param scale       压缩比例(0, 1.0]
     */
    public static void commpressPicForScale(File srcFile, long desFileSize, double scale) {
        try {
            // #0. 获取文件类型，根据内容而不是后缀名
            String type = getPicType(new FileInputStream(srcFile));
            // #1. 判空
            if (srcFile == null || !srcFile.exists() || !srcFile.isFile()) {
                return;
            }
            // #2.输出大小
            long len = srcFile.length();
            logger.info("源图片：" + srcFile.getAbsolutePath() + "，大小：" + len / K + "kb");

            // #3. 递归方法压缩
            compressImage(type, srcFile, desFileSize, scale);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    /**
     * 根据照片类型、精确度,上限大小，压缩指定照片
     *
     * @param type        照片类型：jpg/png (1. type是根据文件的内容定的，而不是名字后缀值； 2. 除了jpg，其他都按照png处理)
     * @param srcFile     源文件和目标文件：用的同一个
     * @param desFileSize 目标值限制大小，单位Kb
     * @param scale       压缩比：(0,1.0]
     */
    private static void compressImage(String type, File srcFile, long desFileSize, double scale) {
        if (srcFile == null || !srcFile.exists() || !srcFile.isFile()) {
            logger.error("_n_待压缩源文件不合要求：srcFile={}", srcFile);
            return;
        }

        try {
            long fileSize = srcFile.length();
            // 1、判断大小，如果小于500kb，不压缩；如果大于等于500kb，压缩:递归结束条件
            if (fileSize <= desFileSize * K) {
                return;
            }
            // 2. jpg格式有不失真的压缩方式；png的没有；
            if (JPG.equalsIgnoreCase(type)) {
                logger.info("jpg_file_compress:{}", srcFile.getAbsoluteFile());
                Thumbnails.of(srcFile).scale(1.0f).outputQuality(scale).toFile(srcFile);
            } else { // 其他图片类型，一律按照PNG格式缩放
                logger.info("png_file_compress:{}", srcFile.getAbsoluteFile());
                Thumbnails.of(srcFile).scale(scale).toFile(srcFile);
            }
            // 3. 记录下压缩后的大小
            logger.info("compressing...{}kb", srcFile.length() / K);
            // 4. 递归调用，直到大小符合要求
            compressImage(type, srcFile, desFileSize, scale);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取base64字符串
     *
     * @param file
     * @return
     */
    public static String getImageBase64(File file) {
        FileInputStream inputFile = null;
        byte[] buffer = new byte[0];

        try {
            // #1. Base64输入流
            inputFile = new FileInputStream(file);
            buffer = new byte[(int) file.length()];
            inputFile.read(buffer);
            inputFile.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally { // 用完后删除文件
            deleteUploadedFile(file);
        }

        return new BASE64Encoder().encode(buffer);
    }

    /**
     * 返回之前，把生成的文件删除掉
     *
     * @param file
     */
    public static void deleteUploadedFile(File file) {
        // 上传完文件之后，照片或视频文件删除掉
        if (file != null && file.exists()) {
            logger.info("file deleting: ", file.getAbsolutePath());
            file.delete();
        }
    }

//    private static String getImageBase64(String imageId) {
//        File orgFile = FtpHelper.getFile(imageId);
//        File file = renameFile(orgFile);
//        ImageUtil.commpressPicForScale(file, 500, 0.9d); // 压缩照片
//        Assert.assertion(file != null, ResponseCodeEnum.INTERNAL_HANDLE_ERROR, "file is not exit");
//        FileInputStream inputFile = null;
//        byte[] buffer = new byte[0];
//        try {
//            inputFile = new FileInputStream(file);
//            buffer = new byte[(int) file.length()];
//            inputFile.read(buffer);
//            inputFile.close();
//        } catch (Exception e) {
//            LOGGER.error("Exception->\n {}", e);
//            throw new ThirdPartException(ResponseCodeEnum.INTERNAL_HANDLE_ERROR, StringMsg.fmtMsg("*"));
//        } finally { // 用完后删除文件
//            FtpHelper.deleteUploadedFile(file);
//            FtpHelper.deleteUploadedFile(orgFile);
//        }
//        return new BASE64Encoder().encode(buffer);
//    }

    public static void main(String[] args) throws FileNotFoundException {
//        File f2 = new File("E:\\chrome_download\\1.png");
//        String type2 = ImageUtil.getPicType(new FileInputStream(f2));
//        System.out.println("type2=" + type2);
////        ImageUtil.compressImage(type2, f2, 500, 0.9d);
//        File pngFile = new File("C:\\Users\\weijun.nie\\Desktop\\thinkstats\\test2.png");
//        File jpgFile = convert2Jpg(pngFile);
//        System.out.println(jpgFile.getAbsolutePath());

        System.out.printf("%02X", 125);
    }
}