<%@ page language="java" pageEncoding="UTF-8"%>
<%@ pagecontentType
="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*,com.swetake.util.Qrcode"%>
<%!Color getRandColor(int fc, int bc) {//給定范圍獲得隨機顏色
   Random random = new Random();
   if (fc > 255)
    fc = 255;
   if (bc > 255)
    bc = 255;
   int r = fc + random.nextInt(bc - fc);
   int g = fc + random.nextInt(bc - fc);
   int b = fc + random.nextInt(bc - fc);
   return new Color(r, g, b);
}%>
<%
//設置頁面不緩存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);

//    在內存中創建圖象
int width = 60, height = 20;
BufferedImage image = new BufferedImage(width, height,
    BufferedImage.TYPE_INT_RGB);

//    獲取圖形上下文
Graphics g = image.getGraphics();

//生成隨機類
Random random = new Random();

//    設定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);

//設定字體
g.setFont(new Font("Comic    Sans    MS", Font.PLAIN, 20));

//畫邊框
//g.setColor(new    Color());
//g.drawRect(0,0,width-1,height-1);

//    隨機產生155條干擾線，使圖象中的認證碼不易被其它程序探測到
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
   int x = random.nextInt(width);
   int y = random.nextInt(height);
   int xl = random.nextInt(12);
   int yl = random.nextInt(12);
   g.drawLine(x, y, x + xl, y + yl);
}

//    取隨機產生的認證碼(4位數字)
String sRand = "";
for (int i = 0; i < 4; i++) {
   String rand = String.valueOf(random.nextInt(10));
   sRand += rand;
   //    將認證碼顯示到圖象中
   g.setColor(new Color(20 + random.nextInt(110), 20 + random   .nextInt(110), 20 + random.nextInt(110)));
   //調用函數出來的顏色相同，可能是因為種子太接近，所以只能直接生成
   g.drawString(rand, 13 * i + 6, 16);
}

//    將認證碼存入SESSION
session.setAttribute("rand", sRand);

//    圖象生效
g.dispose();
out.clear();
out = pageContext.pushBody();

//    輸出圖象到頁面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>

 

注:要先下載com.swetake.util.Qrcode包