写一个验证码

来源：互联网发布：淘宝小镇姗姗模特是谁编辑：程序博客网时间：2024/06/02 11:10

1.导入image.jsp并放到相应的webRoot跟目录下面
2.在相应的地方写如下代码：
验证码：<input type="text" name="irand"><img id="irandImg" src="image.jsp"/><br/>
看不清楚，请点这里<a href="javascript:void(0);" onclick="changeIrand();"/>换一张</a>
3.添加js:
<script type="text/javascript">
   function changeIrand(){
  document.getElementById("irandImg").src = "image.jsp?k="+Math.random();
   }
</script>
4.image.jsp
<%@ page language="java" import="java.util.*" pageEncoding="GB2312"%>
<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc){//给定范围获得随机颜色
        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);
        }
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);

// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 获取图形上下文
Graphics g = image.getGraphics();

//生成随机类
Random random = new Random();

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

//设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));

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

// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
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);
}

// 取随机产生的认证码(4位数字)
String sRand="";
for (int i=0;i<4;i++){
    String rand=String.valueOf(random.nextInt(10));
    sRand+=rand;
    // 将认证码显示到图象中
    g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
    g.drawString(rand,13*i+6,16);
}

// 将认证码存入session
session.setAttribute("rand",sRand);
// 图象生效
g.dispose();

// 输出图象到页面
try{
ImageIO.write(image, "JPEG", response.getOutputStream());
out.clear();
out = pageContext.pushBody();
}catch(Exception e){
e.getMessage();
}
%>