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" />