Java实现二维码生成的代码方法

Java实现二维码生成的代码方法可以通过使用第三方库来实现，比如zxing和google的qrcode。下面我们来分别介绍两种库的使用方法以及两个示例。

zxing库生成二维码的代码方法：

1.首先，需要在项目中引入zxing的Maven依赖：

<dependency>
  <groupId>com.google.zxing</groupId>
  <artifactId>core</artifactId>
  <version>3.3.3</version>
</dependency>
<dependency>
  <groupId>com.google.zxing</groupId>
  <artifactId>javase</artifactId>
  <version>3.3.3</version>
</dependency>

2.然后在代码中调用zxing核心类生成二维码图片：

public static void encode(String contents, String filePath, int width, int height) throws WriterException, IOException {
    Hashtable<EncodeHintType, Object> hints = new Hashtable<>();
    hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
    BitMatrix bitMatrix = new MultiFormatWriter().encode(contents, BarcodeFormat.QR_CODE, width, height, hints);
    Path path = FileSystems.getDefault().getPath(filePath);
    MatrixToImageWriter.writeToPath(bitMatrix, "png", path);
}

其中，contents为二维码的内容，filePath为生成图片的文件路径，width和height为生成图片的宽度和高度。

下面是一个生成带Logo二维码的示例代码：

public static void encodeWithLogo(String contents, String logoPath, String outputFile, int width, int height) throws WriterException, IOException {
    Hashtable<EncodeHintType, Object> hints = new Hashtable<>();
    hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
    BitMatrix bitMatrix = new MultiFormatWriter().encode(contents, BarcodeFormat.QR_CODE, width, height, hints);
    Path path = FileSystems.getDefault().getPath(outputFile);
    MatrixToImageWriter.writeToPath(addLogo(bitMatrix, logoPath), "png", path);
}

private static BufferedImage addLogo(BitMatrix matrix, String logoPath) throws IOException {
    BufferedImage image = MatrixToImageWriter.toBufferedImage(matrix);
    Graphics2D g2 = image.createGraphics();
    int logoWidth = image.getWidth() / 5;
    int logoHeight = image.getHeight() / 5;
    BufferedImage logo = ImageIO.read(new File(logoPath));
    int x = (image.getWidth() - logoWidth) / 2;
    int y = (image.getHeight() - logoHeight) / 2;
    g2.drawImage(logo, x, y, logoWidth, logoHeight, null);
    g2.dispose();
    return image;
}

其中，logoPath为Logo文件的路径，outputFile为输出图片的文件路径。

google的qrcode库生成二维码的代码方法：

1.首先，需要在项目中引入google的qrcode的Maven依赖：

<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>core</artifactId>
    <version>3.3.3</version>
</dependency>
<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>javase</artifactId>
    <version>3.3.3</version>
</dependency>

2.然后在代码中调用google qrcode库生成二维码图片：

public static void encode(String contents, String filePath, int width, int height) throws WriterException, IOException {
    BitMatrix bitMatrix = new QRCodeWriter().encode(contents, BarcodeFormat.QR_CODE, width, height);
    Path path = FileSystems.getDefault().getPath(filePath);
    MatrixToImageWriter.writeToPath(bitMatrix, "png", path);
}

其中，contents为二维码的内容，filePath为生成图片的文件路径，width和height为生成图片的宽度和高度。

下面是一个生成带Logo二维码的示例代码：

public static void encodeWithLogo(String contents, String logoPath, String outputFile, int width, int height) throws WriterException, IOException {
    BitMatrix bitMatrix = new QRCodeWriter().encode(contents, BarcodeFormat.QR_CODE, width, height);
    Path path = FileSystems.getDefault().getPath(outputFile);
    MatrixToImageWriter.writeToPath(addLogo(bitMatrix, logoPath), "png", path);
}

private static BufferedImage addLogo(BitMatrix matrix, String logoPath) throws IOException {
    BufferedImage image = MatrixToImageWriter.toBufferedImage(matrix);
    Graphics2D g2 = image.createGraphics();
    int logoWidth = image.getWidth() / 5;
    int logoHeight = image.getHeight() / 5;
    BufferedImage logo = ImageIO.read(new File(logoPath));
    int x = (image.getWidth() - logoWidth) / 2;
    int y = (image.getHeight() - logoHeight) / 2;
    g2.drawImage(logo, x, y, logoWidth, logoHeight, null);
    g2.dispose();
    return image;
}

其中，logoPath为Logo文件的路径，outputFile为输出图片的文件路径。

以上就是Java实现二维码生成的代码方法的完整攻略，以上示例可以用来生成带Logo的二维码，可以轻松实现自己需要的二维码生成。