登陆验证码
界面JSP代码
<span style="font-family:Comic Sans MS;font-size:18px;"><%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!-- <link rel="stylesheet" type="text/css" href="css/style.css"> -->
<style type="text/css">
</style>
<script type="text/javascript">
function changeCode(){
//多次加载同一张图片，浏览器会缓存，这里所以添加一个参数
var time=new Date().getTime();
document.getElementById("img").src="<%=request.getContextPath()%>/verificationCode?time"+time;
}
</script>
</head>
<body>
<div id="myCode">
<form action="Code" method="POST">
验证码 <input type="text" id="codeInput" name="codeInput" >
<img alt="验证码" id="img" src="<%=request.getContextPath()%>/verificationCode">
<a href="javascript:changeCode();"><img id="reflash" style=" 22px;height: 22px;" src="img/reflash.png"></a>
<br/><input type="submit" value="提交"/>
</form>
</div>
</body>
</html></span>我的Servlet代码<span style="font-family:Comic Sans MS;font-size:18px;">package com.tang.code;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class verificationCode extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/* BufferedImage是Image的一个子类，
BufferedImage生成的图片在内存里有一个图像缓冲区，
利用这个缓冲区我们可以很方便的操作这个图片，通常用来做图片修改操作如大小变换、
图片变灰、设置图片透明或不透明等。
*/
BufferedImage bi=new BufferedImage(68,22,BufferedImage.TYPE_INT_RGB);
//Graphics 类是所有图形上下文的抽象基类，允许应用程序在组件（已经在各种设备上实现）以及闭屏图像上进行绘制。
Graphics g=bi.getGraphics();
Color c=new Color(200,150,255);
g.setColor(c);
/*fillRect(int x,int y,int width, int height)
* x - 要绘制矩形的 x 坐标。
* y - 要绘制矩形的 y 坐标。
* width - 要绘制矩形的宽度。
* height - 要绘制矩形的高度。
*/
g.fillRect(0, 0, 68, 22);
char[] ch="ABCDEFGHIGKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789".toCharArray();
//实例化随机对象
Random r=new Random();
int len=ch.length,index;
StringBuffer sb=new StringBuffer();
for(int i=0;i<4;i++){
//产生0~len长度的随机数
index=r.nextInt(len);
System.out.println("index=r.nextInt(len)："+index);
//设置字的颜色
//new Color(r.nextInt(88),r.nextInt(88),r.nextInt(255))
g.setColor(new Color(r.nextInt(88),r.nextInt(88),r.nextInt(255)));
//drawString(String str, int x, int y) 使用此图形上下文的当前字体和颜色绘制由指定 string 给定的文本。
g.drawString(ch[index]+"",(i*15)+3,18);
sb.append(ch[index]);
}
//保存到session中，在服务器中通过获取session对比验证码是否正确
request.getSession().setAttribute("pircode", sb.toString());
ImageIO.write(bi,"JPG",response.getOutputStream());
}
}</span>