4dkankan-utils/4dkankan-common-utils/src/main/java/com/fdkankan/common/constant/ImageUtil.java

package com.fdkankan.common.constant;

import cn.hutool.core.img.ImgUtil;

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

/**
 * <p>
 * TODO
 * </p>
 *
 * @author dengsixing
 * @since 2022/4/8
 **/
public class ImageUtil {

    public static final String TYPE_JPG = "jpg";
    public static final String TYPE_GIF = "gif";
    public static final String TYPE_PNG = "png";
    public static final String TYPE_BMP = "bmp";
    public static final String TYPE_UNKNOWN = "unknown";

    public static boolean isImage(FileInputStream fis){
        String picType = getPicType(fis);
        if(TYPE_JPG.equals(picType)
            || TYPE_GIF.equals(picType)
            || TYPE_PNG.equals(picType)
            || TYPE_BMP.equals(picType)){
            return true;
        }
        return false;
    }

    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 TYPE_JPG;
            } else if (type.contains("89504E47")) {
                return TYPE_PNG;
            } else if (type.contains("47494638")) {
                return TYPE_GIF;
            } else if (type.contains("424D")) {
                return TYPE_BMP;
            } else {
                return TYPE_UNKNOWN;
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }

    public static String bytesToHexString(byte[] src) {
        StringBuilder stringBuilder = 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) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }

    public static void main(String[] args) throws IOException {
        ByteArrayOutputStream byteArrayOut = new ByteArrayOutputStream();
        String path = "G:\\home\\backend\\4dkankan_v4\\sale\\file\\sale\\file\\test\\5474a1e8d93747f3aec79e6021c10a3b.png";
        String picType = getPicType(new FileInputStream(path));
        System.out.println(picType);
        BufferedImage read = ImgUtil.read(new File(path));
        ImageIO.write(read, "png", byteArrayOut);
    }

}