（转）ZXing解析二维码

1 ZXing解析二维码

上一篇文件已经说过如何用ZXing进行生成二维码和带图片的二维码，下面说下如何解析二维码

二维码的解析和生成类似，也可以参考google的一个操作类 BufferedImageLuminanceSource类，该类可在google的测试包中找到，另外j2se中也有该类，你可以将该类直接拷贝到源码中使用，你也可以自己写个。

1.1 BufferedImageLuminanceSource类

package t1;

import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import com.google.zxing.LuminanceSource;  

/**
 *
 * 二维码的解析需要借助BufferedImageLuminanceSource类，该类是由Google提供的，可以将该类直接拷贝到源码中使用，当然你也可以自己写个
 * 解析条形码的基类
 */  

public final class BufferedImageLuminanceSource extends LuminanceSource {  

  private static final double MINUS_45_IN_RADIANS = -0.7853981633974483; // Math.toRadians(-45.0)  

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

  private static final boolean EXPLICIT_LUMINANCE_CONVERSION;
  static {
    String property = System.getProperty("explicitLuminanceConversion");
    if (property == null) {
      property = System.getenv("EXPLICIT_LUMINANCE_CONVERSION");
    }
    EXPLICIT_LUMINANCE_CONVERSION = Boolean.parseBoolean(property);
  }  

  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);  

    if (image.getType() == BufferedImage.TYPE_BYTE_GRAY) {
      this.image = image;
    } else {
      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.");
      }  

      this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY);  

      if (EXPLICIT_LUMINANCE_CONVERSION) {  

        WritableRaster raster = this.image.getRaster();
        int[] buffer = new int[width];
        for (int y = top; y < top + height; y++) {
          image.getRGB(left, y, width, 1, buffer, 0, sourceWidth);
          for (int x = 0; x < width; x++) {
            int pixel = buffer[x];  

            // see comments in implicit branch
            if ((pixel & 0xFF000000) == 0) {
              pixel = 0xFFFFFFFF; // = white
            }  

            // .229R + 0.587G + 0.114B (YUV/YIQ for PAL and NTSC)
            buffer[x] =
                (306 * ((pixel >> 16) & 0xFF) +
                 601 * ((pixel >> 8) & 0xFF) +
                 117 * (pixel & 0xFF) +
                 0x200) >> 10;
          }
          raster.setPixels(left, y, width, 1, buffer);
        }  

      } else {  

        // The color of fully-transparent pixels is irrelevant. They are often, technically, fully-transparent
        // black (0 alpha, and then 0 RGB). They are often used, of course as the "white" area in a
        // barcode image. Force any such pixel to be white:
        if (image.getAlphaRaster() != null) {
          int[] buffer = new int[width];
          for (int y = top; y < top + height; y++) {
            image.getRGB(left, y, width, 1, buffer, 0, sourceWidth);
            boolean rowChanged = false;
            for (int x = 0; x < width; x++) {
              if ((buffer[x] & 0xFF000000) == 0) {
                buffer[x] = 0xFFFFFFFF; // = white
                rowChanged = true;
              }
            }
            if (rowChanged) {
              image.setRGB(left, y, width, 1, buffer, 0, sourceWidth);
            }
          }
        }  

        // Create a grayscale copy, no need to calculate the luminance manually
        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];
    }
    // The underlying raster of image consists of bytes with the luminance values
    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];
    // The underlying raster of image consists of area bytes with the luminance values
    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);
  }  

  /**
   * This is always true, since the image is a gray-scale image.
   *
   * @return true
   */
  @Override
  public boolean isRotateSupported() {
    return true;
  }  

  @Override
  public LuminanceSource rotateCounterClockwise() {
    int sourceWidth = image.getWidth();
    int sourceHeight = image.getHeight();  

    // Rotate 90 degrees counterclockwise.
    AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);  

    // Note width/height are flipped since we are rotating 90 degrees.
    BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY);  

    // Draw the original image into rotated, via transformation
    Graphics2D g = rotatedImage.createGraphics();
    g.drawImage(image, transform, null);
    g.dispose();  

    // Maintain the cropped region, but rotate it too.
    int width = getWidth();
    return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);
  }  

  @Override
  public LuminanceSource rotateCounterClockwise45() {
    int width = getWidth();
    int height = getHeight();  

    int oldCenterX = left + width / 2;
    int oldCenterY = top + height / 2;  

    // Rotate 45 degrees counterclockwise.
    AffineTransform transform = AffineTransform.getRotateInstance(MINUS_45_IN_RADIANS, oldCenterX, oldCenterY);  

    int sourceDimension = Math.max(image.getWidth(), image.getHeight());
    BufferedImage rotatedImage = new BufferedImage(sourceDimension, sourceDimension, BufferedImage.TYPE_BYTE_GRAY);  

    // Draw the original image into rotated, via transformation
    Graphics2D g = rotatedImage.createGraphics();
    g.drawImage(image, transform, null);
    g.dispose();  

    int halfDimension = Math.max(width, height) / 2;
    int newLeft = Math.max(0, oldCenterX - halfDimension);
    int newTop = Math.max(0, oldCenterY - halfDimension);
    int newRight = Math.min(sourceDimension - 1, oldCenterX + halfDimension);
    int newBottom = Math.min(sourceDimension - 1, oldCenterY + halfDimension);  

    return new BufferedImageLuminanceSource(rotatedImage, newLeft, newTop, newRight - newLeft, newBottom - newTop);
  }  

}  

1.2 操作类：DecodeTest

package t1;

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

import javax.imageio.ImageIO;

import com.google.zxing.Binarizer;
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.common.HybridBinarizer;

/**
 * 解析二维码
 * @author Administrator
 *
 */
public class DecodeHelper {  

    public static void main(String[] args) throws Exception {
         try {
             MultiFormatReader formatReader = new MultiFormatReader();
             String filePath = "e:\\new-1.gif"; //new.png
             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);   

             Hashtable<DecodeHintType, Object> hints = new Hashtable<DecodeHintType, Object>();
             hints.put(DecodeHintType.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();
             }
    }
}  

1.3 补充

a.读取二维码图片，并送给 Zxing LuminanceSource 和 Binarizer 两兄弟的处理。

b.处理完的位图和相应的解析参数，交由 MultiFormatReader 处理，并返回解析后的结果。

c.如果对上述 两兄弟的处理 和 MultiFormatReader  的解析有兴趣，可以读读源码。

 本博客与二维码相关的文章：

（转）ZXing生成二维码和带logo的二维码，模仿微信生成二维码效果
（转）js jquery.qrcode生成二维码 带logo 支持中文