java生成二维码图片

1.依赖

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <version>2.7.18</version>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
      <version>2.7.18</version>
    </dependency>
    <dependency>
      <groupId>com.google.zxing</groupId>
      <artifactId>javase</artifactId>
      <version>3.5.2</version>
      <scope>compile</scope>
    </dependency>

2.代码

package org.example.qrcode;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import org.springframework.mock.web.MockMultipartFile;
import org.springframework.web.multipart.MultipartFile;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class MyQrcode {
    public static MultipartFile generateQrCode(String content, int width, int height) {
        MultipartFile multipartFile = null;
        try {
            Map<EncodeHintType, Object> hints = new HashMap<>();
            hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
            hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);

            BitMatrix bitMatrix = null;
            bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, width, height, hints);
            BufferedImage bufferedImage = MatrixToImageWriter.toBufferedImage(bitMatrix);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ImageIO.write(bufferedImage,"png",new File("./ad.png"));
            ImageIO.write(bufferedImage, "png", baos);
            byte[] imageBytes = baos.toByteArray();
            ByteArrayInputStream bais = new ByteArrayInputStream(imageBytes);
            String fileName = "qrcode.png";
            multipartFile = new MockMultipartFile("file", fileName, "image/png", bais);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return multipartFile;
    }
    public static void main(String[] args) throws IOException {
        generateQrCode("中国", 300, 300);
    }
}

3.说明

代码中有两次ImageIO.write的方法，第一个是把二维码图片存储到了指定的路径，适合本地测试；第二个是把文件流通过multipartFile返回了，适合生成二维码文件流后上传到服务器的操作。两个方法留一个即可。