JAVA生成二维码

生成二维码需要要用到Google的core3.0.0.jar
而这个jar包要求JDK版本为7.0以上。
因为优快云传文件有大小限制，所以我传到百度云上面，这里面包含了JDK7和core3.0.0
链接: https://pan.baidu.com/s/1i5cnwKt 密码: 76rm
JSP端显示图片：

  <img src="webToWeixinPay.action?&a=<%  
                                              Random a = new Random();  
                                              out.print(a.nextInt(100));//若要生成1-100的随机数则改为a.nextInt(100)+1即可  
                                              %>  "> 

获得URL，生成二维码：

       //要生成二维码的url,我这个url是微信支付生成的。
       String urlCode = "weixin://wxpay/bizpayurl?pr=yG8B9dr";

        //生成二维码 
        int width = 100;
        int height = 100;
        String format = "png";
        Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();
        hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
        BitMatrix bitMatrix = new MultiFormatWriter().encode(urlCode,
                BarcodeFormat.QR_CODE, width, height, hints);

        // 禁止图像缓存。
        this.getHttpServletResponse().setHeader("Pragma", "no-cache");
        this.getHttpServletResponse().setHeader("Cache-Control", "no-cache");
        this.getHttpServletResponse().setDateHeader("Expires", 0);

        this.getHttpServletResponse().setContentType("image/jpeg");

        // 将图像输出到Servlet输出流中。
        ServletOutputStream sos = this.getHttpServletResponse().getOutputStream();
        MatrixToImageWriter.writeToStream(bitMatrix, format, sos);
        sos.close();

图片输出所需要的代码：

package julit.weixin.test;

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); 
    } 
  } 

}