在java中生成二维码，并直接输出到jsp页面

迷南。 2022-08-21 04:52 172阅读 0赞

在java中生成的二维码不存到磁盘里要直接输出到页面上，这就需要把生成的二维码直接以流的形式输出到页面上，我用的是myeclipse 和 tomcat

它的原理是：在加载页面时，根据img的src(code.jspx)找到对应的servlet(CodeServlet)，在servlet中编辑二维码中的内容，调用生成二维码的类EncoderHandler中的encoderQRcoder方法

1.首先要导入jar包（将jar包放到lib目录下）

导入jar包的名称为：Qrcode\_swetake

下载jar包的连接[http://download.csdn.net/detail/junlong750/9109003][http_download.csdn.net_detail_junlong750_9109003]

2.在java中生成二维码并以流的形式输出

package com.imooc.util;
    
    import java.awt.Color;
    import java.awt.Graphics2D;
    import java.awt.image.BufferedImage;
    
    import javax.imageio.ImageIO;
    import javax.servlet.http.HttpServletResponse;
    
    import com.swetake.util.Qrcode;
    
    
    public class QRCodeUtils {
    	
    	public void encoderQRCoder(String content, HttpServletResponse response) {
    		try {
    			Qrcode handler = new Qrcode();
    			handler.setQrcodeErrorCorrect('M');
    			handler.setQrcodeEncodeMode('B');
    			handler.setQrcodeVersion(7);
    			
    			System.out.println(content);
    			byte[] contentBytes = content.getBytes("UTF-8");
    			
    			BufferedImage bufImg = new BufferedImage(80, 80, BufferedImage.TYPE_INT_RGB);
    			
    			Graphics2D gs = bufImg.createGraphics();
    			
    			gs.setBackground(Color.WHITE);
    			gs.clearRect(0, 0, 140, 140);
    			
    			//设定图像颜色：BLACK
    			gs.setColor(Color.BLACK);
    			
    			//设置偏移量  不设置肯能导致解析出错
    			int pixoff = 2;
    			//输出内容：二维码
    			if(contentBytes.length > 0 && contentBytes.length < 124) {
    				boolean[][] codeOut = handler.calQrcode(contentBytes);
    				for(int i = 0; i < codeOut.length; i++) {
    					for(int j = 0; j < codeOut.length; j++) {
    						if(codeOut[j][i]) {
    							gs.fillRect(j * 3 + pixoff, i * 3 + pixoff,3, 3);
    						}
    					}
    				}
    			} else {
    				System.err.println("QRCode content bytes length = " + contentBytes.length + " not in [ 0,120 ]. ");
    			}
    			
    			gs.dispose();
    			bufImg.flush();
    			
    			
    			
    			//生成二维码QRCode图片
    			ImageIO.write(bufImg, "jpg", response.getOutputStream());
    			
    			
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    }

3.建立一个servlet

package com.imooc.servlet;
    
    
    
    import java.io.IOException;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import com.imooc.util.QRCodeUtils;
    /**
     * 
     * @author longjun
     *
     */
    public class CodeServlet extends HttpServlet {
    
    	private static final long serialVersionUID = 1L;
    	
    	@Override
    	protected void service(HttpServletRequest requset, HttpServletResponse response)
    			throws ServletException, IOException {
    		String content = "姓名:longjun 电话:123687495";
    		QRCodeUtils encoder = new QRCodeUtils();
    		encoder.encoderQRCoder(content, response);
    	}
    
    }

4在web.xml中的配置

<servlet>
        <servlet-name>CodeService</servlet-name>
        <servlet-class>com.imooc.servlet.CodeServlet</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>CodeService</servlet-name>
        <url-pattern>/code.jspx</url-pattern>
      </servlet-mapping>

5.jsp中的img(其中img的src为对应的CodeServlet的url)

[http_download.csdn.net_detail_junlong750_9109003]: http://download.csdn.net/detail/junlong750/9109003