Java实现二维码技术探讨。

Java生成二维码方法有三种：

1： 使用SwetakeQRCode在Java项目中生成二维码 
http://swetake.com/qr/ 下载地址 
或着http://sourceforge.jp/projects/qrcode/downloads/28391/qrcode.zip 
这个是日本人写的，生成的是我们常见的方形的二维码 
可以用中文 如：5677777ghjjjjj 

2： 使用BarCode4j生成条形码和二维码 
BarCode4j网址：http://sourceforge.net/projects/barcode4j/ 

barcode4j是使用datamatrix的二维码生成算法，为支持qr的算法 
datamatrix是欧美的标准，qr为日本的标准， 
barcode4j一般生成出来是长方形的

如：88777alec000yan 
这个博客这方面说的挺清楚的： 
http://baijinshan.iteye.com/blog/1004554

3、现在详细介绍第三种也是常用的方式：利用Zxing生成二维码

Zxing是Google提供的关于条码（一维码、二维码）的解析工具，提供了二维码的生成与解析的方法，现在我简单介绍一下使用Java利用Zxing生成与解析二维码。

第一步:将Zxing-core.jar 包加入项目中。

第二步 添加以下三个Java文件，三个文件功能如下：

MatrixToImageWriter.java  生成二维码图片。

BufferedImageLuminanceSource.java   解析二维码图片。

BarcodeFactory.java  生成带头像的二维码。

MatrixToImageWriter.java

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 java.io.File;
import java.io.OutputStream;
import java.io.IOException;
import java.util.Hashtable;
import java.awt.image.BufferedImage;

public final class MatrixToImageWriter {

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

	private MatrixToImageWriter() {
	}

	public 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;
	}

	public 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);
		}
	}

	public 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);
		}
	}
	
	public static void main(String[] args) throws Exception {
		String text = "二维码内容，可以是链接也可以是文本";
		int width = 300;
		int height = 300;
		Hashtable hints = new Hashtable();
		hints.put(EncodeHintType.CHARACTER_SET, "utf-8");//内容所使用编码  
		BitMatrix bitMatrix = new MultiFormatWriter().encode(text, BarcodeFormat.QR_CODE, width, height, hints);

		File outputFile = new File("E:/qrtest/生成普通二维码.jpg");
		//File.separator
		String format = "jpg";//二维码的图片格式  
		MatrixToImageWriter.writeToFile(bitMatrix, format, outputFile);

	}
}

import com.google.zxing.Binarizer;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.EncodeHintType;
import com.google.zxing.LuminanceSource;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.Result;
import com.google.zxing.common.HybridBinarizer;

import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.HashMap;
import java.util.Map;

import javax.imageio.ImageIO;

public final class BufferedImageLuminanceSource extends LuminanceSource {

	private final BufferedImage image;
	private final int left;
	private final int top;

	public BufferedImageLuminanceSource(BufferedImage image) {
		this(image, 0, 0, image.getWidth(), image.getHeight());
	}

	public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width, int height) {
		super(width, height);

		int sourceWidth = image.getWidth();
		int sourceHeight = image.getHeight();
		if (left + width > sourceWidth || top + height > sourceHeight) {
			throw new IllegalArgumentException("Crop rectangle does not fit within image data.");
		}

		for (int y = top; y < top + height; y++) {
			for (int x = left; x < left + width; x++) {
				if ((image.getRGB(x, y) & 0xFF000000) == 0) {
					image.setRGB(x, y, 0xFFFFFFFF); // = white
				}
			}
		}

		this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY);
		this.image.getGraphics().drawImage(image, 0, 0, null);
		this.left = left;
		this.top = top;
	}

	@Override
	public byte[] getRow(int y, byte[] row) {
		if (y < 0 || y >= getHeight()) {
			throw new IllegalArgumentException("Requested row is outside the image: " + y);
		}
		int width = getWidth();
		if (row == null || row.length < width) {
			row = new byte[width];
		}
		image.getRaster().getDataElements(left, top + y, width, 1, row);
		return row;
	}

	@Override
	public byte[] getMatrix() {
		int width = getWidth();
		int height = getHeight();
		int area = width * height;
		byte[] matrix = new byte[area];
		image.getRaster().getDataElements(left, top, width, height, matrix);
		return matrix;
	}

	@Override
	public boolean isCropSupported() {
		return true;
	}

	@Override
	public LuminanceSource crop(int left, int top, int width, int height) {
		return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height);
	}

	@Override
	public boolean isRotateSupported() {
		return true;
	}

	@Override
	public LuminanceSource rotateCounterClockwise() {

		int sourceWidth = image.getWidth();
		int sourceHeight = image.getHeight();

		AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);

		BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY);

		Graphics2D g = rotatedImage.createGraphics();
		g.drawImage(image, transform, null);
		g.dispose();

		int width = getWidth();
		return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);
	}

	public static void main(String[] args) {
		//解析二维码
		try {
			MultiFormatReader formatReader = new MultiFormatReader();
			String filePath = "E:/qrtest/生成普通二维码.jpg";
			File file = new File(filePath);
			BufferedImage image = ImageIO.read(file);
			LuminanceSource source = new BufferedImageLuminanceSource(image);
			Binarizer binarizer = new HybridBinarizer(source);
			BinaryBitmap binaryBitmap = new BinaryBitmap(binarizer);
			
			Map hints = new HashMap();
			hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
			Result result = formatReader.decode(binaryBitmap, hints);

			System.out.println("result = " + result.toString());
			System.out.println("resultFormat = " + result.getBarcodeFormat());
			System.out.println("resultText = " + result.getText());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

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;


public class BarcodeFactory {
	// 图片宽度的一般
	private static final int IMAGE_WIDTH = 80;
	private static final int IMAGE_HEIGHT = 80;
	private static final int IMAGE_HALF_WIDTH = IMAGE_WIDTH / 2;
	private static final int FRAME_WIDTH = 2;

	// 二维码写码器
	private static MultiFormatWriter mutiWriter = new MultiFormatWriter();

	/**
	 * 将srcImagePath嵌入到destImagePath
	 */
	public static void encode(String content, int width, int height, String srcImagePath, String destImagePath) {
		try {
			ImageIO.write(genBarcode(content, width, height, srcImagePath), "jpg", new File(destImagePath));
		} catch (IOException e) {
			e.printStackTrace();
		} catch (WriterException e) {
			e.printStackTrace();
		}
	}

	private static BufferedImage genBarcode(String content, int width, int height, String srcImagePath)
			throws WriterException, IOException {
		// 读取源图像
		BufferedImage scaleImage = scale(srcImagePath, IMAGE_WIDTH, IMAGE_HEIGHT, true);
		int[][] srcPixels = new int[IMAGE_WIDTH][IMAGE_HEIGHT];
		for (int i = 0; i < scaleImage.getWidth(); i++) {
			for (int j = 0; j < scaleImage.getHeight(); j++) {
				srcPixels[i][j] = scaleImage.getRGB(i, j);
			}
		}

		Map<EncodeHintType, Object> hint = new HashMap<EncodeHintType, Object>();
		hint.put(EncodeHintType.CHARACTER_SET, "utf-8");
		hint.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);
		// 生成二维码
		BitMatrix matrix = mutiWriter.encode(content, BarcodeFormat.QR_CODE, width, height, hint);

		// 二维矩阵转为一维像素数组
		int halfW = matrix.getWidth() / 2;
		int halfH = matrix.getHeight() / 2;
		int[] pixels = new int[width * height];

		for (int y = 0; y < matrix.getHeight(); y++) {
			for (int x = 0; x < matrix.getWidth(); x++) {
				// 读取图片
				if (x > halfW - IMAGE_HALF_WIDTH && x < halfW + IMAGE_HALF_WIDTH && y > halfH - IMAGE_HALF_WIDTH
						&& y < halfH + IMAGE_HALF_WIDTH) {
					pixels[y * width + x] = srcPixels[x - halfW + IMAGE_HALF_WIDTH][y - halfH + IMAGE_HALF_WIDTH];
				}
				// 在图片四周形成边框
				else if ((x > halfW - IMAGE_HALF_WIDTH - FRAME_WIDTH && x < halfW - IMAGE_HALF_WIDTH + FRAME_WIDTH
						&& y > halfH - IMAGE_HALF_WIDTH - FRAME_WIDTH && y < halfH + IMAGE_HALF_WIDTH + FRAME_WIDTH)
						|| (x > halfW + IMAGE_HALF_WIDTH - FRAME_WIDTH && x < halfW + IMAGE_HALF_WIDTH + FRAME_WIDTH
								&& y > halfH - IMAGE_HALF_WIDTH - FRAME_WIDTH && y < halfH + IMAGE_HALF_WIDTH + FRAME_WIDTH)
						|| (x > halfW - IMAGE_HALF_WIDTH - FRAME_WIDTH && x < halfW + IMAGE_HALF_WIDTH + FRAME_WIDTH
								&& y > halfH - IMAGE_HALF_WIDTH - FRAME_WIDTH && y < halfH - IMAGE_HALF_WIDTH + FRAME_WIDTH)
						|| (x > halfW - IMAGE_HALF_WIDTH - FRAME_WIDTH && x < halfW + IMAGE_HALF_WIDTH + FRAME_WIDTH
								&& y > halfH + IMAGE_HALF_WIDTH - FRAME_WIDTH && y < halfH + IMAGE_HALF_WIDTH + FRAME_WIDTH)) {
					pixels[y * width + x] = 0xfffffff;
				} else {
					// 此处可以修改二维码的颜色，可以分别制定二维码和背景的颜色；
					pixels[y * width + x] = matrix.get(x, y) ? 0xff000000 : 0xfffffff;
				}
			}
		}

		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		image.getRaster().setDataElements(0, 0, width, height, pixels);

		return image;
	}

	/**
	 * 把传入的原始图像按高度和宽度进行缩放，生成符合要求的图标
	 * 
	 * @param srcImageFile
	 *            源文件地址
	 * @param height
	 *            目标高度
	 * @param width
	 *            目标宽度
	 * @param hasFiller
	 *            比例不对时是否需要补白：true为补白; false为不补白;
	 * @throws IOException
	 */
	private static BufferedImage scale(String srcImageFile, int height, int width, boolean hasFiller) throws IOException {
		double ratio = 0.0; // 缩放比例
		File file = new File(srcImageFile);
		BufferedImage srcImage = ImageIO.read(file);
		Image destImage = srcImage.getScaledInstance(width, height, BufferedImage.SCALE_SMOOTH);
		// 计算比例
		if ((srcImage.getHeight() > height) || (srcImage.getWidth() > width)) {
			if (srcImage.getHeight() > srcImage.getWidth()) {
				ratio = (new Integer(height)).doubleValue() / srcImage.getHeight();
			} else {
				ratio = (new Integer(width)).doubleValue() / srcImage.getWidth();
			}
			AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(ratio, ratio), null);
			destImage = op.filter(srcImage, null);
		}
		if (hasFiller) {// 补白
			BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
			Graphics2D graphic = image.createGraphics();
			graphic.setColor(Color.white);
			graphic.fillRect(0, 0, width, height);
			if (width == destImage.getWidth(null))
				graphic.drawImage(destImage, 0, (height - destImage.getHeight(null)) / 2, destImage.getWidth(null), destImage
						.getHeight(null), Color.white, null);
			else
				graphic.drawImage(destImage, (width - destImage.getWidth(null)) / 2, 0, destImage.getWidth(null), destImage
						.getHeight(null), Color.white, null);
			graphic.dispose();
			destImage = image;
		}
		return (BufferedImage) destImage;
	}

	public static void main(String[] args) {
		//src.jpg为头像文件
		BarcodeFactory.encode("http://www.baidu.com", 300, 300, "E:/qrtest/src.jpg","E:/qrtest/生成带头像的二维码.jpg");
	}
}