（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。

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