生成二维码

近来客户资料需要归档，用二维码来存储一些信息，为此特学习了二维码如何生成。

1. 需要的依赖如下

<dependency>  
	<groupId>com.google.zxing</groupId>  
	<artifactId>core</artifactId>  
	<version>3.3.1</version>  
</dependency>  
<dependency>  
	<groupId>com.google.zxing</groupId>  
	<artifactId>javase</artifactId>  
	<version>3.3.1</version>  
</dependency>

2. 二维码示例

可以加logo，也可以画上一些文字

3. 示例代码

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;
import java.util.UUID;
import javax.imageio.ImageIO;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import com.google.zxing.qrcode.encoder.ByteMatrix;
import com.google.zxing.qrcode.encoder.Encoder;
import com.google.zxing.qrcode.encoder.QRCode;

public class QrCode {
	static final int BLACK = 0xFF000000;
	static final int WHITE = 0xFFFFFFFF;
	static final int QUIET_ZONE_SIZE = 4;// 边框大小参数

	public static void main(String[] args) throws IOException, WriterException {

		String text = "C:\\springboot-tomcat-tmp\\upload\\QRCode\\20180119";
		writeToStreamEntire(text, 500, 500, "", "", null);

	}

	public static void writeToStreamEntire(String text, int width, int height, String format, String newPath, Object o)
			throws IOException, WriterException {
      
		String p = "C:\\springboot-tomcat-tmp\\upload\\QRCode\\20180119";
		//图片生成后的路径
		newPath = p + File.separator + UUID.randomUUID() + ".jpg";
		//预设置二维码大小  非实际值 
		width = 200;
		height = 200;

		System.out.println("writeToStreamEntire 入参: " + "text : " + text + " ,width=" + width + ",height=" + height
				+ " ,format=" + format + ",newPath=" + newPath);
		Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();
		hints.put(EncodeHintType.CHARACTER_SET, "utf-8"); // 内容所使用字符集编码
		hints.put(EncodeHintType.ERROR_CORRECTION, "Q");// 容错率 共四种级别

		BitMatrix bitMatrix = new MultiFormatWriter().encode(text, BarcodeFormat.QR_CODE, width, height, hints);
		// 用户获取偏移 二维码 空白部分的偏移
		Map<String, Integer> xy = getXY(text, BarcodeFormat.QR_CODE, width, height, hints);

		// 二维码实际大小 包括边框
		int widthR = bitMatrix.getWidth();
		int heightR = bitMatrix.getHeight();

		// 图片实际像素大小 实际的大小不能小于 二维码输出的大小 否则 扫不出来
		int outHight = heightR + 500;

		int outWidth = widthR + 500;

		BufferedImage image = new BufferedImage(outWidth, outHight, BufferedImage.TYPE_INT_RGB);

		for (int x = 0; x < outWidth; x++) {
			for (int y = 0; y < outHight; y++) {
				if (x < widthR && y < heightR) {
					image.setRGB(x, y, bitMatrix.get(x, y) ? BLACK : WHITE);
				} else {
					image.setRGB(x, y, WHITE);
				}
			}
		}
		FileOutputStream stream = null;

		// 中间加 个人图片

		Graphics2D gs = image.createGraphics();

		int ratioWidth = widthR * 2 / 10;
		int ratioHeight = heightR * 2 / 10;
		// 载入logo
		String logoPath = "C:\\Users\\lixia\\Desktop\\java\\毕业季\\me.jpg";
		Image img = ImageIO.read(new File(logoPath));
		int logoWidth = img.getWidth(null) > ratioWidth ? ratioWidth : img.getWidth(null);
		int logoHeight = img.getHeight(null) > ratioHeight ? ratioHeight : img.getHeight(null);

		int x = (widthR - logoWidth) / 2;
		int y = (heightR - logoHeight) / 2;

		gs.drawImage(img, x, y, logoWidth, logoHeight, null);
		gs.setColor(Color.black);
		gs.setBackground(Color.WHITE);
		gs.dispose();
		img.flush();

		try {
			stream = new FileOutputStream(newPath);
			if (!ImageIO.write(image, "jpg", stream)) {
				throw new IOException("Could not write an image of format " + format);
			}
			// stream.write("四大地方地方".getBytes());
		} finally {
			if (stream != null) {
				stream.close();
			}
		}
		try {
			// 读取原图片信息
			File srcImgFile = new File(newPath);
			Image srcImg = ImageIO.read(srcImgFile);
			int srcImgWidth = srcImg.getWidth(null);
			int srcImgHeight = srcImg.getHeight(null);

			// 加水印  加工生成的图片
			BufferedImage bufImg = new BufferedImage(srcImgWidth, srcImgHeight, BufferedImage.TYPE_INT_RGB);
			Graphics2D g = bufImg.createGraphics();
			// 将生成的图片 读取出来 花在新的 图片对象上 若宽和高于图片本身不一致，则进行缩放 画到新的图片对象中
			g.drawImage(srcImg, 0, 0, widthR, heightR, null);

			// 设置字体大小
			// 根据最小字体大小设置
			int min = widthR > heightR ? heightR : widthR;
			int fontSize = (heightR - xy.get("Y") * 2) / 6;
			Font font = new Font("宋体", Font.PLAIN, fontSize - fontSize * 2 / 10);
			g.setColor(Color.white); // 根据图片的背景设置水印颜色
			g.setFont(font);

			// 设置右边偏移
			int rightX = widthR + widthR * 2 / 10;

			int rightY = xy.get("Y") + fontSize - fontSize * 2 / 10;

			g.drawString("客户姓名：" + "李显春", rightX, rightY);
			g.drawString("业务类型：" + "李显春", rightX, rightY + fontSize * 1);
			g.drawString("品牌：" + "李显春", rightX, rightY + fontSize * 2);
			g.drawString("车牌号：" + "李显春", rightX, rightY + fontSize * 3);
			g.drawString("管理类型：" + "李显春", rightX, rightY + fontSize * 4);
			g.drawString("档案管理：" + "李显春", rightX, rightY + fontSize * 5);

			// 设置下边偏移
			int downX = xy.get("X");
			int downY = heightR + heightR * 2 / 10;
			g.drawString("档案编号：" + "李显春", downX, downY);
			g.drawString("合同号：" + "CPHZ20170504N000007", downX, downY + fontSize * 1);
			g.drawString("车架号：" + "HT20170408CG0004", downX, downY + fontSize * 2);
			g.drawString("资料清单：" + "归档资料（售后回租个人）", downX, downY + fontSize * 3);
			g.drawString("经销商名称：" + "woshi", downX, downY + fontSize * 4);
			g.dispose();
			// 输出图片
			FileOutputStream outImgStream = new FileOutputStream(newPath);
			ImageIO.write(bufImg, "jpg", outImgStream);
			outImgStream.flush();
			outImgStream.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	// 获取偏移
	public static Map<String, Integer> getXY(String contents, BarcodeFormat format, int width, int height,
			Map<EncodeHintType, ?> hints) throws WriterException {

		if (contents.isEmpty()) {
			throw new IllegalArgumentException("Found empty contents");
		}

		if (format != BarcodeFormat.QR_CODE) {
			throw new IllegalArgumentException("Can only encode QR_CODE, but got " + format);
		}

		if (width < 0 || height < 0) {
			throw new IllegalArgumentException("Requested dimensions are too small: " + width + 'x' + height);
		}

		ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;
		int quietZone = QUIET_ZONE_SIZE;
		if (hints != null) {
			if (hints.containsKey(EncodeHintType.ERROR_CORRECTION)) {
				errorCorrectionLevel = ErrorCorrectionLevel
						.valueOf(hints.get(EncodeHintType.ERROR_CORRECTION).toString());
			}
			if (hints.containsKey(EncodeHintType.MARGIN)) {
				quietZone = Integer.parseInt(hints.get(EncodeHintType.MARGIN).toString());
			}
		}

		QRCode code = Encoder.encode(contents, errorCorrectionLevel, hints);

		ByteMatrix input = code.getMatrix();
		if (input == null) {
			throw new IllegalStateException();
		}
		int inputWidth = input.getWidth();
		int inputHeight = input.getHeight();
		int qrWidth = inputWidth + (quietZone * 2);
		int qrHeight = inputHeight + (quietZone * 2);
		int outputWidth = Math.max(width, qrWidth);
		int outputHeight = Math.max(height, qrHeight);

		int multiple = Math.min(outputWidth / qrWidth, outputHeight / qrHeight);

		int leftPadding = (outputWidth - (inputWidth * multiple)) / 2;
		int topPadding = (outputHeight - (inputHeight * multiple)) / 2;

		Map<String, Integer> map = new HashMap<>();
		map.put("X", leftPadding);
		map.put("Y", topPadding);
		return map;
	}

}

4. 注意与总结

1 理论上来讲，二维码是限的，就从图片上的点数也可以发现，不过数量应该巨大，还不知道是如何编码解析的。
2 生成的二维码大小和边框是自动计算的，不能手动设置。
3 二维码是有容错率的，即使部分丢失，也是可以扫出来的，因为编码有冗余。