數(shù)字驗(yàn)證碼是一種最常用的驗(yàn)證字符碼形式，以下為數(shù)字實(shí)現(xiàn)的JSP源碼： Num.jsp
<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %><%!
Color getRandColor(int cc,int bb)
{
Random random = new Random();
if(fc>255) cc=255;
if(bc>255) bb=255;
int r=cc+random.nextInt(bb-cc);
int g=cc+random.nextInt(bb-cc);
int b=cc+random.nextInt(bb-cc);
returnnew Color(r,g,b);
} //獲取隨機(jī)顏色
%>
<%
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
int width=80; //定義驗(yàn)證碼圖片的長度
int height=30; //定義驗(yàn)證碼圖片的寬度
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
//定義字體形式
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
int i_x = random.nextInt(width);
int i_y = random.nextInt(height);
int i_xl = random.nextInt(12);
int i_yl = random.nextInt(12);
g.drawLine(i_x,i_y,i_x+i_xl,i_y+i_yl);
}
//用線條畫背景
String s_Rand="";
for (int i=0;i<4;i++)
{
String rand=String.valueOf(random.nextInt(10));
s_Rand+=rand;
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
g.drawString(rand,13*i+6,16);
}
//產(chǎn)生4位隨機(jī)碼
session.setAttribute("rand",s_Rand);
//將驗(yàn)證碼存入Session中
g.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
//輸出驗(yàn)證圖片
