java生成二维码、条形码和二维码、条形码的解码

首先，使用java生成二维码和条形码需要ZXing

ZXing是一个开源Java类库用于解析多种格式的条形码和二维码.

官网：http://code.google.com/p/zxing/

MatrixToImageWriter类辅助生成二维码，该类是由Google提供的，我们可以把它复制到自己的项目中使用：

下面是MatrixToImageWriter类的源代码：

package learn;

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

import javax.imageio.ImageIO;

import com.google.zxing.common.BitMatrix;

public class WriteBitMatricToFile {
	private static final int BLACK = 0xFF000000;
	private static final int WHITE = 0xFFFFFFFF;

	private static BufferedImage toBufferedImage(BitMatrix bm) {
		int width = bm.getWidth();
		int height = bm.getHeight();
		BufferedImage image = new BufferedImage(width, height,
		        BufferedImage.TYPE_3BYTE_BGR);
		for (int i = 0; i < width; i++) {
			for (int j = 0; j < height; j++) {
				image.setRGB(i, j, bm.get(i, j) ? BLACK : WHITE);
			}
		}
		return image;
	}

	public static void writeBitMatricToFile(BitMatrix bm, String format,
	        File file) {
		BufferedImage image = toBufferedImage(bm);
		try {
			if (!ImageIO.write(image, format, file)) {
				throw new RuntimeException("Can not write an image to file" + file);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	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);
		}
	}
}

生成二维码和条形码的格式不同，二维码的编码格式是二维码的格式是BarcodeFormat.QR_CODE，条形码的编码格式是条形码的格式是 BarcodeFormat.EAN_13 ，下面是源代码：

package learn;

import java.io.File;
import java.util.HashMap;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.common.BitMatrix;

public class EncodeTest {
	public static void main(String[] args) throws Exception {
		int width = 300;
		int height = 300;
		// int width = 105;
		// int height = 50;
		// 条形码的输入是13位的数字
		// String text = "6923450657713";
		// 二维码的输入是字符串
		String text = "testtesttest生成条形码图片";
		String format = "png";
		HashMap<EncodeHintType, String> hints = new HashMap<>();
		hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
		// 条形码的格式是 BarcodeFormat.EAN_13
		// 二维码的格式是BarcodeFormat.QR_CODE
		BitMatrix bm = new MultiFormatWriter().encode(text,
		        BarcodeFormat.QR_CODE, width, height, hints);

		File out = new File("new.png");
		// 生成条形码图片
		// File out = new File("ean3.png");

		WriteBitMatricToFile.writeBitMatricToFile(bm, format, out);
	}

}

以下是生成的二维码和条形码：

条形码的输入是6923450657713

解码的过程就是二值化使用Binarizer实现，一维码使用getBlackRow方法，二维码的使用getBlackMatrix方法。Binarizer有两个生成类，GlobalHistogramBinarizer和HybridBinarizer；这两个类对getBlackMatrix方法的实现有不同，但使用时都是一样的没什么分别。

如果对解码过程感兴趣的话，可以阅读：http://blog.csdn.net/mihenyinghua/article/details/17224019

解码时需要zxing-j2se.jar，将jar添加到classpath下。

package learn;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
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.LuminanceSource;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.Result;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.GlobalHistogramBinarizer;

public class DecodeTest {
	public static void main(String[] args) throws Exception {
		// 这里可以是条形图片码或者二维码图片
		// 这是二维码图片
		BufferedImage bi = ImageIO.read(new FileInputStream(new File("new.png")));
		// 这是条形码图片
		// BufferedImage bi = ImageIO.read(new FileInputStream(new
		// File("ean3.png")));
		if (bi != null) {
			Map<DecodeHintType, String> hints = new HashMap<>();
			hints.put(DecodeHintType.CHARACTER_SET, "utf-8");
			LuminanceSource source = new BufferedImageLuminanceSource(bi);
			// 这里还可以是 BinaryBitmap bitmap = new BinaryBitmap(new
			// HybridBinarizer(source));
			BinaryBitmap bitmap = new BinaryBitmap(
			        new GlobalHistogramBinarizer(source));
			Result res = new MultiFormatReader().decode(bitmap, hints);
			System.out.println(res);
			System.out.println("decode successfully!");
		}
	}
}

参考资料：http://blog.csdn.net/mihenyinghua/article/details/17224019