jsp开发中图片验证码的简单实现
image.jsp
login.jsp
validate.jsp
<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="gbk"%>
<%!
Color getRandColor(int fc,int bc)
{
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);
}
%>
<%
out.clear();//这句针对resin服务器，如果是tomacat可以不要这句
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
int width=60, height=20;
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));
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);
}
char c[] = new char[62];
for (int i = 97, j = 0; i < 123; i++, j++) {
c[j] = (char) i;
}
for (int o = 65, p = 26; o < 91; o++, p++) {
c[p] = (char) o;
}
for (int m = 48, n = 52; m < 58; m++, n++) {
c[n] = (char) m;
}
String sRand="";
for (int i=0;i<4;i++){
int x = random.nextInt(62);
String rand=String.valueOf(c[x]);
sRand+=rand;
//String sRand="";
//for (int i=0;i<4;i++){
//String rand=String.valueOf(random.nextInt(10));
//sRand+=rand;
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);
g.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
out.clear();
out = pageContext.pushBody();
%>
login.jsp
<%@ page language="java" pageEncoding="gbk"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>用户登录</title>
<script language="javascript">
function loadimage(){
document.getElementById("randImage").src = "image.jsp?"+Math.random();
}
</script>
</head>
<body>
<form action="validate.jsp" method="post" name="loginForm">
<table width="256" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="118" height="22" valign="middle" align="center">
<input type="text" name="rand" size="15">
</td>
<td width="138" valign="middle" align="center">
<img alt="code..." name="randImage" id="randImage" src="image.jsp"
width="60" height="20" border="1" >
</td>
</tr>
<tr>
<td height="36" colspan="2" align="center" valign="middle">
<a href="javascript:loadimage();"><font class=pt95>看不清点我</font>
</a>
<input type=button value="test" onclick="alert('${sessionScope.rand}')"/>
</td>
</tr>
<tr>
<td height="36" colspan="2" align="center" valign="middle">
<input type="submit" name="login" value="提交">
</td>
</tr>
</table>
</form>
</body>
</html>
validate.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" pageEncoding="gbk" %>
<%
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
if(rand.equals(input)){
out.print("<script>alert('验证通过！');</script>");
} else{
out.print("<script>alert('请输入正确的验证码！');location.href='login.jsp';</script>");
}
%>