java使用jar包生成二维码的示例代码

下面是Java使用jar包生成二维码的完整攻略：

1. 引入Jar包

在Java中使用二维码需要引入第三方Jar包，可以使用Zxing或者QrCode这两个常用的Jar包。这里以Zxing为例，可以从官网或者Maven库中下载获取。

2. 生成二维码

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.net.URL;

import javax.imageio.ImageIO;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.qrcode.QRCodeWriter;

public class QRCodeGenerator {

    public static void main(String[] args) throws Exception {

        String url = "https://www.baidu.com";
        int size = 250;
        String fileType = "png";
        File qrFile = new File("E:/qrcode.png");

        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        BitMatrix bitMatrix = qrCodeWriter.encode(url, BarcodeFormat.QR_CODE, size, size);

        BufferedImage bufferedImage = MatrixToImageWriter.toBufferedImage(bitMatrix, getMatrixConfig());

        //添加Logo
        URL logoUrl = new URL("https://ss0.bdstatic.com/6Ox1bjeh1BF3odCf/it/u=305420187,2505743536&fm=26&gp=0.jpg");
        BufferedImage logoImage = ImageIO.read(logoUrl);
        int logoWidth = bufferedImage.getWidth()/5;
        int logoHeight = bufferedImage.getHeight()/5;
        int logoX = (bufferedImage.getWidth()-logoWidth)/2;
        int logoY = (bufferedImage.getHeight()-logoHeight)/2;

        Graphics2D graphics = bufferedImage.createGraphics();
        graphics.drawImage(logoImage, logoX, logoY, logoWidth, logoHeight, null);
        graphics.setColor(Color.BLACK);
        graphics.drawRect(logoX, logoY, logoWidth, logoHeight);
        graphics.dispose();

        ImageIO.write(bufferedImage, fileType, qrFile);
    }

    private static int BLACK = 0xFF000000;
    private static int WHITE = 0xFFFFFFFF;

    private static BufferedImageOp getMatrixConfig() {
        return new BufferedImageOp() {
            @Override
            public BufferedImage filter(BufferedImage src, BufferedImage dest) {
                int qrWidth = src.getWidth();
                int qrHeight = src.getHeight();
                BufferedImage image = new BufferedImage(qrWidth, qrHeight, BufferedImage.TYPE_INT_RGB);
                for (int y = 0; y < qrHeight; y++) {
                    for (int x = 0; x < qrWidth; x++) {
                        image.setRGB(x, y, src.get(x, y) == true ? BLACK : WHITE);
                    }
                }
                return image;
            }
        };
    }
}

以上代码演示了如何使用Zxing生成一个含有Logo的二维码，具体实现步骤如下：

1. 定义二维码链接地址和大小；
2. 使用QRCodeWriter.encode方法生成二维码；
3. 利用MatrixToImageWriter.toBufferedImage将二维码转换为BufferedImage；
4. 添加Logo图片；
5. 将BufferedImage输出为图片。

3. 读取二维码

import java.awt.image.BufferedImage;
import java.io.File;
import java.util.HashMap;
import java.util.Map;

import javax.imageio.ImageIO;

import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.Result;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.HybridBinarizer;

public class QRCodeReader {

    public static void main(String[] args) {

        String filePath = "E:/qrcode.png";
        File qrFile = new File(filePath);

        try {
            BufferedImage bufferedImage = ImageIO.read(qrFile);
            BinaryBitmap binaryBitmap = new BinaryBitmap(new HybridBinarizer(new BufferedImageLuminanceSource(bufferedImage)));
            Map<DecodeHintType, Object> hints = new HashMap<>();
            hints.put(DecodeHintType.CHARACTER_SET, "UTF-8");
            Result result = new MultiFormatReader().decode(binaryBitmap, hints);
            System.out.println("二维码内容：" + result.getText());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

以上代码演示了如何使用Zxing读取一个二维码，具体实现步骤如下：

1. 读取二维码图片；
2. 转成BufferedImage类型；
3. 将BufferedImage转换为BinaryBitmap；
4. 使用MultiFormatReader.decode方法解码二维码，并返回Result对象；
5. 从Result对象中获取二维码内容。

以上就是Java使用Jar包生成二维码的完整攻略，希望能帮到你。