生成有4个随机数字和杂乱背景的图片,数字和背景颜色会改变,服务器端刷新(用history.go(-1)也会变)
原型参考ALIBABA http://china.alibaba.com/member/showimage------------产生验证码图片的文件-----image.jsp-------------------------------------------<%@ 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)));//调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成
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
ImageIO.write(image, "JPEG", response.getOutputStream());%> ---------------使用验证码图片的文件---------a.jsp------------------------------------<%@ page contentType="text/html;charset=gb2312" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>认证码输入页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head>
<body>
<form method=post action="check.jsp">
<table>
<tr>
<td align=left>系统产生的认证码:</td>
<td><img border=0 src="image.jsp"></td>
</tr>
<tr>
<td align=left>输入上面的认证码:</td>
<td><input type=text name=rand maxlength=4 value=""></td>
</tr>
<tr>
<td colspan=2 align=center><input type=submit value="提交检测"></td>
</tr>
</form>
</body>
</html>-----------------验证的页面----------check.jsp<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<html>
<head>
<title>认证码验证页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head><body>
<%
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
%>
系统产生的认证码为: <%= rand %><br>
您输入的认证码为: <%= input %><br>
<br>
<%
if (rand.equals(input)) {
%>
<font color=green>输入相同,认证成功!</font>
<%
} else {
%>
<font color=red>输入不同,认证失败!</font>
<%
}
%>
</body>
</html>
原型参考ALIBABA http://china.alibaba.com/member/showimage------------产生验证码图片的文件-----image.jsp-------------------------------------------<%@ 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)));//调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成
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
ImageIO.write(image, "JPEG", response.getOutputStream());%> ---------------使用验证码图片的文件---------a.jsp------------------------------------<%@ page contentType="text/html;charset=gb2312" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>认证码输入页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head>
<body>
<form method=post action="check.jsp">
<table>
<tr>
<td align=left>系统产生的认证码:</td>
<td><img border=0 src="image.jsp"></td>
</tr>
<tr>
<td align=left>输入上面的认证码:</td>
<td><input type=text name=rand maxlength=4 value=""></td>
</tr>
<tr>
<td colspan=2 align=center><input type=submit value="提交检测"></td>
</tr>
</form>
</body>
</html>-----------------验证的页面----------check.jsp<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<html>
<head>
<title>认证码验证页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head><body>
<%
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
%>
系统产生的认证码为: <%= rand %><br>
您输入的认证码为: <%= input %><br>
<br>
<%
if (rand.equals(input)) {
%>
<font color=green>输入相同,认证成功!</font>
<%
} else {
%>
<font color=red>输入不同,认证失败!</font>
<%
}
%>
</body>
</html>
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<%@ page import="java.awt.*"%>
<%@ page import="java.awt.image.*"%>
<%@ page import="java.util.*"%>
<%@ page import="javax.imageio.*"%>
<%
//在内存中创建图象
int iWidth=130,iHeight=18;
BufferedImage image=new BufferedImage(iWidth,iHeight,BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphics g=image.getGraphics();
//设定背景色
g.setColor(Color.white);
g.fillRect(0,0,iWidth,iHeight);
//画边框
g.setColor(Color.black);
g.drawRect(0,0,iWidth-1,iHeight-1);
//取随机产生的认证码(4位数字)
String rand=request.getParameter("Rand");
rand=rand.substring(0,rand.indexOf("."));
switch(rand.length())
{
case 1:rand="000"+rand;break;
case 2:rand="00"+rand;break;
case 3:rand="0"+rand;break;
default:rand=rand.substring(0,4);break;
}
//将认证码存入SESSION
session.setAttribute("Rand",rand);
//将认证码显示到图象中
g.setColor(Color.black);
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
g.drawString(rand,10,15);
//随机产生88个干扰点,使图象中的认证码不易被其它程序探测到
Random random=new Random();
for(int iIndex=0;iIndex<88;iIndex++)
{
int x=random.nextInt(iWidth);
int y=random.nextInt(iHeight);
g.drawLine(x,y,x,y);
}
//图象生效
g.dispose();
//输出图象到页面
ImageIO.write(image,"JPEG",response.getOutputStream());
%> 输出时应用验证码<script>document.write("<img border=0 src='/image.jsp?Rand="+Math.random()*10000+"'>");</script><br>
输认证码: <input name="Rand" maxlength=4 size="10"><br> 登录认证: String Rand=request.getParameter("Rand");
String strRand=(String)session.getAttribute("Rand");
if(!strRand.equals(Rand))
{
//未通过;
}