zxing生成和解析二维码

今天忙了一天的二维码，用了QRcode和ZXing两个开源包。结果发现

ZXing比QRcode更好用一些，它直接可以定义二维码生成图案的大小，而QRcode生成的二维码是根据二维码包含的内容多少来定的。所以生成的二维码图片大小不好确定。

下面主要说一下ZXing生成二维码的方法：

　　ZXing是google的开源资源，但是由于中国的某些原因使得访问谷歌的资源比较难，所以在网上找到了一个可以下载的连接：http://www.cr173.com/soft/65529.html

　　下载好需要的核心jar包后我们还需要下载一个可以将资源输出到文件或流的工具类MatrixToImageWriter，以下是百度到的源码：

package zxingTest;
import com.google.zxing.common.BitMatrix;
 
 import javax.imageio.ImageIO;
 import java.io.File;
 import java.io.OutputStream;
 import java.io.IOException;
 import java.awt.image.BufferedImage;
 
 
 public final class MatrixToImageWriter  {
 
   private static final int BLACK = 0xFF000000;
   private static final int WHITE = 0xFFFFFFFF;
 
   private MatrixToImageWriter() {}
 
   
   public static BufferedImage toBufferedImage(BitMatrix matrix) {
     int width = matrix.getWidth();
     int height = matrix.getHeight();
     BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
     for (int x = 0; x < width; x++) {
       for (int y = 0; y < height; y++) {
         image.setRGB(x, y, matrix.get(x, y) ? BLACK : WHITE);
       }
     }
     return image;
   }
 
   
   public static void writeToFile(BitMatrix matrix, String format, File file)
       throws IOException {
     BufferedImage image = toBufferedImage(matrix);
     if (!ImageIO.write(image, format, file)) {
       throw new IOException("Could not write an image of format " + format + " to " + file);
     }
   }
 
   
   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);
     }
   }
 
 }

接下来需要写一个测试类了，不过我已经测试过了，并进行了简单包装：

package zxingTest;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Hashtable;

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

public class TwoDimCodeUtil {

    /**
     * @Title: writeToFile 将二维码输出到文件
     * @Description: 将二维码输出到文件
     * @param fileName 文件名称
     * @param contents  二维码包含的内容
     * @param encodeType  字符编码
     * @param imgSize  二维码生成图片大小,单位像素
     * @param imgType 图片格式，jpg,png等
     * @throws
     */
    public static void writeToFile(String fileName,String contents,String encodeType,int imgSize,String imgType){
        Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();  
        hints.put(EncodeHintType.CHARACTER_SET,encodeType);  
        BitMatrix matrix = null;  
        try {  
            matrix = new MultiFormatWriter().encode(contents,BarcodeFormat.QR_CODE, imgSize, imgSize, hints);  
            File file = new File(fileName);  
            MatrixToImageWriter.writeToFile(matrix, imgType, file);  
        } catch (WriterException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
                e.printStackTrace();  
            }  
    }
    
    /**
     * @Title: writeToFile 将二维码输出到流
     * @Description: 将二维码输出到流
     * @param outputStream 输出流
     * @param contents  二维码包含的内容
     * @param encodeType  字符编码
     * @param imgSize  二维码生成图片大小
     * @param imgType 图片格式，jpg,png等
     * @throws
     */
    public static void writeToStream(OutputStream outputStream,String contents,String encodeType,int imgSize,String imgType){
        Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();  
        hints.put(EncodeHintType.CHARACTER_SET,encodeType);  
        BitMatrix matrix = null;  
        try {  
            matrix = new MultiFormatWriter().encode(contents,BarcodeFormat.QR_CODE, imgSize, imgSize, hints);  
            MatrixToImageWriter.writeToStream(matrix, imgType, outputStream);
        } catch (WriterException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
                e.printStackTrace();  
        }  
    }
    
    /**
     * @Title: writeToFile 将二维码输出到流,默认编码utf-8，文件类型jpg
     * @Description: 将二维码输出到流
     * @param outputStream 输出流
     * @param contents  二维码包含的内容
     * @param imgSize  二维码生成图片大小
     * @throws
     */
    public static void writeToStream(OutputStream outputStream,String contents,int imgSize){
        TwoDimCodeUtil.writeToStream(outputStream, contents, "UTF-8", imgSize, "jpg");
    }
}

下面是调用的一个例子：

public void showQRCode(){
        HttpServletRequest request=this.getRequest();
        HttpServletResponse response=this.getResponse();
        response.setHeader("Pragma","No-cache");
        response.setHeader("Cache-Control","no-cache");
        response.setDateHeader("Expires", 0);
        response.setContentType("image/jpeg"); 
        
        String content=request.getParameter("content");
        String widthstr= request.getParameter("width");
        int width=(widthstr==null||widthstr.equals(""))?140:Integer.valueOf(widthstr);
        System.out.println(content);
        try {
            TwoDimCodeUtil.writeToStream(response.getOutputStream(), content, width);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

页面调用：

<img src="/showQRCode.do?content=helloworld&width=140" />