?? image.jsp
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<%@ page contentType="image/jpeg"
import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"
pageEncoding="gb2312"%>
<%
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
try {
//在內存中創建圖象
int width = 60; //圖像的寬度
int height = 20; //圖像的高度
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
//獲取圖形上下文
Graphics g = image.getGraphics();
//設定背景色
g.setColor(new Color(0xDCDCDC));
g.fillRect(0, 0, width, height);
//畫邊框
g.setColor(Color.black);
g.drawRect(0, 0, width - 1, height - 1);
//取隨機產生的認證碼(4位數字)
Random random = new Random();
//生成0-9999的隨機數
int randomNum = random.nextInt(9999);
//將驗證碼存在session中
// session.setAttribute("rand",sRand);
request.getSession().setAttribute("rand",
String.valueOf(randomNum));
String randStr = String.valueOf(randomNum);
switch (randStr.length()) {
case 1:
randStr = "000" + randStr;
break;
case 2:
randStr = "00" + randStr;
break;
case 3:
randStr = "0" + randStr;
break;
default:
randStr = randStr.substring(0, 4);
break;
}
//將認證碼顯示到圖象中
g.setColor(Color.black);
g.setFont(new Font("Atlantic Inline", Font.PLAIN, 18));
String Str = randStr.substring(0, 1);
g.drawString(Str, 8, 17);
Str = randStr.substring(1, 2);
g.drawString(Str, 20, 15);
Str = randStr.substring(2, 3);
g.drawString(Str, 35, 18);
Str = randStr.substring(3, 4);
g.drawString(Str, 45, 15);
// 隨機產生88個干擾點,使圖象中的認證碼不易被其它程序探測到
for (int i = 0; i < 20; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
g.drawOval(x, y, random.nextInt(5), random.nextInt(5));
}
// 圖象生效
g.dispose();
// 輸出圖象到頁面
ImageIO.write(image, "JPEG", response.getOutputStream());
out.clear();
out = pageContext.pushBody();
} catch (Exception e) {
e.printStackTrace();
out.println(e.toString());
}
%>
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