使用zxing进行QR码编码和解码

Question

好吧，所以我要打消这里有人以前使用过 zxing 的可能性。我正在开发一个Java应用程序，它需要做的一件事是将数据的字节数组编码为QR码，然后稍后对其进行解码。

这是我的编码器的示例：

byte[] b = {0x48, 0x45, 0x4C, 0x4C, 0x4F};
//convert the byte array into a UTF-8 string
String data;
try {
    data = new String(b, "UTF8");
}
catch (UnsupportedEncodingException e) {
 //the program shouldn't be able to get here
 return;
}

//get a byte matrix for the data
ByteMatrix matrix;
com.google.zxing.Writer writer = new QRCodeWriter();
try {
 matrix = writer.encode(data, com.google.zxing.BarcodeFormat.QR_CODE, width, height);
}
catch (com.google.zxing.WriterException e) {
 //exit the method
 return;
}

//generate an image from the byte matrix
int width = matrix.getWidth(); 
int height = matrix.getHeight(); 

byte[][] array = matrix.getArray();

//create buffered image to draw to
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

//iterate through the matrix and draw the pixels to the image
for (int y = 0; y < height; y++) { 
 for (int x = 0; x < width; x++) { 
  int grayValue = array[y][x] & 0xff; 
  image.setRGB(x, y, (grayValue == 0 ? 0 : 0xFFFFFF));
 }
}

//write the image to the output stream
ImageIO.write(image, "png", outputStream);

此代码中的起始字节数组仅用于测试它。实际的字节数据会有所不同。

我的解码器如下所示：

//get the data from the input stream
BufferedImage image = ImageIO.read(inputStream);

//convert the image to a binary bitmap source
LuminanceSource source = new BufferedImageLuminanceSource(image);
BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));

//decode the barcode
QRCodeReader reader = new QRCodeReader();

Result result;
try {
 result = reader.decode(bitmap, hints);
} catch (ReaderException e) {
 //the data is improperly formatted
 throw new MCCDatabaseMismatchException();
}

byte[] b = result.getRawBytes();
System.out.println(ByteHelper.convertUnsignedBytesToHexString(result.getText().getBytes("UTF8")));
System.out.println(ByteHelper.convertUnsignedBytesToHexString(b));

convertUnsignedBytesToHexString(byte) 是一种将字节数组转换为十六进制字符字符串的方法。

当我尝试一起运行这两个代码块时，这是输出：

48454c4c4f
202b0b78cc00ec11ec11ec11ec11ec11ec11ec

显然文本正在被编码，但实际的数据字节完全关闭。任何帮助将不胜感激。

Answer 1

因此，对于那些不想花两天时间在互联网上搜索来解决这个问题的人来说，当您将字节数组编码为 QR 码时，您必须使用 ISO-8859-1字符集，而不是 UTF-8。

Answer 2

这是我的工作示例 Java 代码，使用 ZXing 和 UTF-8 编码对 QR 代码进行编码，请注意：您需要将路径和 utf8 数据更改为您的路径和语言字符

package com.mypackage.qr;

import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.util.Hashtable;

import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.*;

public class CreateQR {

public static void main(String[] args)
{
    Charset charset = Charset.forName("UTF-8");
    CharsetEncoder encoder = charset.newEncoder();
    byte[] b = null;
    try {
        // Convert a string to UTF-8 bytes in a ByteBuffer
        ByteBuffer bbuf = encoder.encode(CharBuffer.wrap("utf 8 characters - i used hebrew, but you should write some of your own language characters"));
        b = bbuf.array();
    } catch (CharacterCodingException e) {
        System.out.println(e.getMessage());
    }

    String data;
    try {
        data = new String(b, "UTF-8");
        // get a byte matrix for the data
        BitMatrix matrix = null;
        int h = 100;
        int w = 100;
        com.google.zxing.Writer writer = new MultiFormatWriter();
        try {
            Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>(2);
            hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
            matrix = writer.encode(data,
            com.google.zxing.BarcodeFormat.QR_CODE, w, h, hints);
        } catch (com.google.zxing.WriterException e) {
            System.out.println(e.getMessage());
        }

        // change this path to match yours (this is my mac home folder, you can use: c:\\qr_png.png if you are on windows)
                String filePath = "/Users/shaybc/Desktop/OutlookQR/qr_png.png";
        File file = new File(filePath);
        try {
            MatrixToImageWriter.writeToFile(matrix, "PNG", file);
            System.out.println("printing to " + file.getAbsolutePath());
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
    } catch (UnsupportedEncodingException e) {
        System.out.println(e.getMessage());
    }
}

}

Answer 3

就其价值而言，我的常规尖峰似乎适用于 UTF-8 和 ISO-8859-1 字符编码。不确定当非 zxing 解码器尝试解码 UTF-8 编码图像时会发生什么...可能因设备而异。

// ------------------------------------------------------------------------------------
// Requires: groovy-1.7.6, jdk1.6.0_03, ./lib with zxing core-1.7.jar, javase-1.7.jar 
// Javadocs: http://zxing.org/w/docs/javadoc/overview-summary.html
// Run with: groovy -cp "./lib/*" zxing.groovy
// ------------------------------------------------------------------------------------

import com.google.zxing.*
import com.google.zxing.common.*
import com.google.zxing.client.j2se.*

import java.awt.image.BufferedImage
import javax.imageio.ImageIO

def class zxing {
    def static main(def args) {
        def filename = "./qrcode.png"
        def data = "This is a test to see if I can encode and decode this data..."
        def charset = "UTF-8" //"ISO-8859-1" 
        def hints = new Hashtable<EncodeHintType, String>([(EncodeHintType.CHARACTER_SET): charset])

        writeQrCode(filename, data, charset, hints, 100, 100)

        assert data == readQrCode(filename, charset, hints)
    }

    def static writeQrCode(def filename, def data, def charset, def hints, def width, def height) {
        BitMatrix matrix = new MultiFormatWriter().encode(new String(data.getBytes(charset), charset), BarcodeFormat.QR_CODE, width, height, hints)
        MatrixToImageWriter.writeToFile(matrix, filename.substring(filename.lastIndexOf('.')+1), new File(filename))
    }

    def static readQrCode(def filename, def charset, def hints) {
        BinaryBitmap binaryBitmap = new BinaryBitmap(new HybridBinarizer(new BufferedImageLuminanceSource(ImageIO.read(new FileInputStream(filename)))))
        Result result = new MultiFormatReader().decode(binaryBitmap, hints)

        result.getText()        
    }

}

Answer 4

如果确实需要编码 UTF-8，可以尝试在前面添加 unicode 字节顺序标记。我不知道这种方法的支持有多广泛，但 ZXing 至少看起来支持它：
http://code.google.com/p/zxing/issues/ detail?id=103

我最近一直在阅读 QR 模式，我认为我在其他地方看到过相同的做法，但我不知道最模糊的地方。

Answer 5

我尝试使用 ISO-8859-1，如第一个答案中所述。编码一切顺利，但是当我尝试使用解码结果字符串获取 byte[] 时，所有负字节都变成了字符 63（问号）。下面的代码不起作用：

// Encoding works great
byte[] contents = new byte[]{-1};
QRCodeWriter codeWriter = new QRCodeWriter();
BitMatrix bitMatrix = codeWriter.encode(new String(contents, Charset.forName("ISO-8859-1")), BarcodeFormat.QR_CODE, w, h);

// Decodes like this fails
LuminanceSource ls = new BufferedImageLuminanceSource(encodedBufferedImage);
Result result = new QRCodeReader().decode(new BinaryBitmap( new HybridBinarizer(ls)));
byte[] resultBytes = result.getText().getBytes(Charset.forName("ISO-8859-1")); // a byte[] with byte 63 is given
return resultBytes;

它看起来很奇怪，因为一个非常旧的版本中的API（不确切知道）有一个运行良好的方法：

Vector byteSegments = result.getByteSegments();

所以我尝试搜索为什么这个方法被删除并意识到有一种方法通过元数据获取 ByteSegments。所以我的解码方法如下所示：

// Decodes like this works perfectly
LuminanceSource ls = new BufferedImageLuminanceSource(encodedBufferedImage);
Result result = new QRCodeReader().decode(new BinaryBitmap( new HybridBinarizer(ls)));
Vector byteSegments = (Vector) result.getResultMetadata().get(ResultMetadataType.BYTE_SEGMENTS);  
int i = 0;
int tam = 0;
for (Object o : byteSegments) {
    byte[] bs = (byte[])o;
    tam += bs.length;
}
byte[] resultBytes = new byte[tam];
i = 0;
for (Object o : byteSegments) {
    byte[] bs = (byte[])o;
    for (byte b : bs) {
        resultBytes[i++] = b;
    }
}
return resultBytes;

Answer 6

也许值得一看 QRGen，它构建在 ZXing 之上，并支持具有这种语法的 UTF-8 ：

// if using special characters don't forget to supply the encoding
VCard johnSpecial = new VCard("Jöhn Dɵe")
                        .setAdress("ëåäöƞ Sträät 1, 1234 Döestüwn");
QRCode.from(johnSpecial).withCharset("UTF-8").file();