jsp中显示验证码的代码怎么写?
1个回答
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import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
/*生成验证码图片
*/
public class MakeCertPic {
//验证码图片中可以出现的字符集,可以根据需要修改
private char mapTable[]={
'a','b','c','d','e','f',
'g','h','i','j','k','l',
'm','n','o','p','q','r',
's','t','u','v','w','x',
'y','z','0','1','2','3',
'4','5','6','7','8','9'
};
/* 功能:生成彩色验证码图片
参数wedth为生成图片的宽度,参数height为生成图片的高度,参数os为页面的输出流
*/
public String getCertPic(int width,int height,OutputStream os){
if(width<=0)
width=60;
if(height<=0)
height=20;
BufferedImage image= new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphics g = image.getGraphics();
//设定背景颜色
g.setColor(new Color(0xDCDCDC));
g.fillRect(0,0,width,height);
//画边框
g.setColor(Color.black);
g.drawRect(0,0,width-1,height-1);
//随机产生的验证码
String strEnsure = "";
//4代表4为验证码,如果要产生更多位的验证码,则加大数值
for(int i = 0;i<4;++i){
strEnsure += mapTable[(int) (mapTable.length*Math.random())];
}
//将认证码显示到图像中,如果要生成更多位的验证码,增加drawString语句
g.setColor(Color.black);
g.setFont(new Font("Atlantic Inline",Font.PLAIN,18));
String str = strEnsure.substring(0,1);
g.drawString(str,8,17);
str = strEnsure.substring(1,2);
g.drawString(str, 20, 15);
str = strEnsure.substring(2,3);
g.drawString(str, 35, 18);
str = strEnsure.substring(3,4);
g.drawString(str, 45, 15);
//随机产生15个干扰点
Random rand = new Random();
for(int i=0; i<10; i++){
int x = rand.nextInt(width);
int y = rand.nextInt(height);
g.drawOval(x,y,1,1);
}
//释放图形上下文
g.dispose();
try{
//输出图形到页面
ImageIO.write(image, "JPEG", os);
}catch (IOException e){
return "";
}
return strEnsure;
}
}
makeCertPic.jsp页面用于调用生成验证码图片的JavaBean,并在客户端显示,源代码如下:
<%@page contentType="image/jpeg" %><%@page language="java" pageEncoding="utf-8"%><jsp:useBean id="image" scope="page" class="securityCode.pic.MakeCertPic"/><%
String str = image.getCertPic(0,0,response.getOutputStream());
//将验证码存入session中
session.setAttribute("certCode",str);
%>
下边是登录页面:
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>验证码测试登录页面</title>
<script type="text/javascript">
function changeimg()
{
var myimg = document.getElementById("code");
now = new Date();
myimg.src="makeCertPic.jsp?code="+now.getTime();
}
</script>
</head>
<body>
<center>
<form action="loginCheck.jsp" method="post" />
用户名:<input type="text" name="username" /><br>
密 码:<input type="password" name="password"/><br>
验证码:<input type="text" name="certCode"/>
<img id="code" src="makeCertPic.jsp"><a href="javascript:changeimg()">看不清,换一张 </a><br>
<input type="submit" value="登录"/>
</form>
</center>
</body>
</html>
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