Java 使用zxing进行二维码编解码
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QR Code encoding and decoding using zxing
提问by LandonSchropp
Okay, so I'm going to take the off chance that someone here has used zxing before. I'm developing a Java application, and one of the things it needs to do is encode a byte array of data into a QR Code and then decode it at a later time.
好的，所以我要抓住这里有人以前使用过 zxing 的机会。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二维码，然后稍后对其进行解码。
Here's an example of what my encoder looks like:
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);
The beginning byte array in this code is just used to test it. The actual byte data will be varied.
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。
Here's what my decoder looks like:
这是我的解码器的样子：
//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)is a method which converts an array of bytes in a string of hexadecimal characters.
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。
When I try to run these two blocks of code together, this is the output:
当我尝试将这两个代码块一起运行时，这是输出：
48454c4c4f
202b0b78cc00ec11ec11ec11ec11ec11ec11ec
Clearly the text is being encoded, but the actual bytes of data are completely off. Any help would be appreciated here.
显然文本正在被编码，但数据的实际字节完全关闭。任何帮助将不胜感激。
采纳答案by LandonSchropp
So, for future reference for anybody who doesn't want to spend two days searching the internet to figure this out, when you encode byte arrays into QR Codes, you have to use the ISO-8859-1character set, not UTF-8.
因此，为了给不想花两天时间在互联网上搜索以解决这个问题的任何人的未来参考，当您将字节数组编码为二维码时，您必须使用ISO-8859-1字符集，而不是UTF-8.
回答by perennialmind
If you really need to encode UTF-8, you can try prepending the unicode byte order mark. I have no idea how widespread the support for this method is, but ZXing at least appears to support it: http://code.google.com/p/zxing/issues/detail?id=103
如果您确实需要对 UTF-8 进行编码，您可以尝试在 unicode 字节顺序标记之前添加。我不知道对这种方法的支持有多广泛，但 ZXing 至少似乎支持它：http: //code.google.com/p/zxing/issues/detail?id=103
I've been reading up on QR Mode recently, and I thinkI've seen the same practice mentioned elsewhere, but I've not the foggiest where.
我最近一直在阅读 QR 模式，我想我在其他地方看到过同样的做法，但我没有最迷茫的地方。
回答by BrunoJCM
I tried using ISO-8859-1 as said in the first answer. All went ok on encoding, but when I tried to get the byte[] using result string on decoding, all negative bytes became the character 63 (question mark). The following code does not work:
我尝试使用 ISO-8859-1，如第一个答案中所述。编码一切正常，但是当我尝试在解码时使用结果字符串获取字节 [] 时，所有负字节都变成了字符 63（问号）。以下代码不起作用：
// 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;
It looks so strange because the API in a very old version (don't know exactly) had a method thar works well:
看起来很奇怪，因为在一个非常旧的版本（不知道确切）中的 API 有一个方法 thar 工作得很好：
Vector byteSegments = result.getByteSegments();
So I tried to search why this method was removed and realized that there is a way to get ByteSegments, through metadata. So my decode method looks like:
所以我试图搜索为什么这个方法被删除并意识到有一种方法可以通过元数据获取 ByteSegments。所以我的解码方法看起来像：
// 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;
回答by Shaybc
this is my working example Java code to encode QR code using ZXing with UTF-8 encoding, please note: you will need to change the path and utf8 data to your path and language characters
这是我的工作示例 Java 代码，使用 ZXing 和 UTF-8 编码对二维码进行编码，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());
}
}
}
回答by klassek
For what it's worth, my groovy spike seems to work with both UTF-8 and ISO-8859-1 character encodings. Not sure what will happen when a non zxing decoder tries to decode the UTF-8 encoded image though... probably varies depending on the device.
就其价值而言，我的 groovy 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()
}
}
回答by lucrussell
Maybe worth looking at QRGen, which is built on top of ZXing and supports UTF-8 with this kind of syntax:
也许值得一看QRGen，它建立在 ZXing 之上并支持 UTF-8 与这种语法：
// if using special characters don't forget to supply the encoding
VCard johnSpecial = new VCard("J?hn D?e")
.setAdress("????? Str??t 1, 1234 D?estüwn");
QRCode.from(johnSpecial).withCharset("UTF-8").file();
