import com.google.zxing.BarcodeFormat;

import com.google.zxing.EncodeHintType;

import com.google.zxing.MultiFormatWriter;

import com.google.zxing.common.BitMatrix;

import javax.imageio.ImageIO;

import javax.swing.filechooser.FileSystemView;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.IOException;

import java.io.OutputStream;

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.HashMap;

import java.util.Map;

import java.util.UUID;

/**

 * @Description：短连接生成二维码的工具类（需要导入core-3.*.*.jar包）

 * @author : LMH

 * @date : 2020/8/29 9:24

 */

public class QrcodeUtil {

    /**

     * 测试用例生成图片到本地桌面

     * @param args

     */

    public static void main(String[] args) {

        String url = "http://www.baidu.com";

        String path = FileSystemView.getFileSystemView().getHomeDirectory() + File.separator + "testQrcode";

        System.out.println(path);

        String fileName = new SimpleDateFormat("yyyyMMddHHmmss").format(new Date())+ UUID.randomUUID() + ".jpg";

        createQrCode(url, path, fileName);

    }

    /**

     * 生成二维码的方法，其中主要有三个参数

     * @param url 短连接地址

     * @param path  图片存放地址

     * @param fileName  文件名称

     * @return

     */

    public static String createQrCode(String url, String path, String fileName) {

        try {

            Map<EncodeHintType, String> hints = new HashMap<>();

            hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");

            BitMatrix bitMatrix = new MultiFormatWriter().encode(url, BarcodeFormat.QR_CODE, 400, 400, hints);

            File file = new File(path, fileName);

            if (file.exists() || ((file.getParentFile().exists() || file.getParentFile().mkdirs()) && file.createNewFile())) {

                writeToFile(bitMatrix, "jpg", file);

                System.out.println("测试完成：" + file);

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

        return null;

    }

    static void writeToFile(BitMatrix matrix, String format, File file) throws IOException {

        BufferedImage image = toBufferedImage(matrix);

        if (!ImageIO.write(image, format, file)) {

            throw new IOException("Could not write an image of format " + format + " to " + file);

        }

    }

    static void writeToStream(BitMatrix matrix, String format, OutputStream stream) throws IOException {

        BufferedImage image = toBufferedImage(matrix);

        if (!ImageIO.write(image, format, stream)) {

            throw new IOException("Could not write an image of format " + format);

        }

    }

    private static final int BLACK = 0xFF000000;

    private static final int WHITE = 0xFFFFFFFF;

    private static BufferedImage toBufferedImage(BitMatrix matrix) {

        int width = matrix.getWidth();

        int height = matrix.getHeight();

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        for (int x = 0; x < width; x++) {

            for (int y = 0; y < height; y++) {

                image.setRGB(x, y, matrix.get(x, y) ? BLACK : WHITE);

            }

        }

        return image;

    }

}