J2EE动态生成验证码可刷新
1、使用servlet生成验证码
package com.free.util;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class CodeMakerServlet extends HttpServlet
{
/**
*
*/
private static final long serialVersionUID = 1L;
//生成随机类
Random random = new Random();
//验证码字体
private Font[] codeFont =
{
new Font("Times New Roman", Font.PLAIN,18),
new Font("Times New Roman", Font.PLAIN, 18),
new Font("Times New Roman", Font.PLAIN,18),
new Font("Times New Roman", Font.PLAIN, 18)
};
//验证码数字颜色
private Color[] color =
{
Color.BLACK, Color.RED, Color.DARK_GRAY, Color.BLUE
};
String codeNumbers = "";
int width = 60, height = 20;
// 处理 HTTP get 请求
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
System.out.println("生成验证码");
// 清空缓冲区
response.reset();
// 注意这里的MIME类型
response.setContentType("image/png");
// 设置页面不缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 创建一个图像,验证码显示的图片大小
BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
// 设置背景
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
for (int i = 0; i < 4; i++)
{
drawCode(g, i);
}
//添加干扰线
drawNoise(g, 12);
// 绘制边框
//g.setColor(Color.gray);
//g.drawRect(0, 0, width - 1, height - 1);
// 将验证码内容保存进session中，用于验证用户输入是否正确时使用
HttpSession session = request.getSession(true);
session.removeAttribute("rand");
session.setAttribute("rand", codeNumbers);
// 重设字符串
codeNumbers = "";
// 利用ImageIO类的write方法对图像进行编码
ServletOutputStream sos = response.getOutputStream();
ImageIO.write(image, "PNG", sos);
sos.close();
}
// 绘制验证码
public void drawCode(Graphics graphics, int i)
{
String number = String.valueOf(random.nextInt(10));
graphics.setFont(codeFont[i]);
graphics.setColor(color[i]);
//绘制验证码到图片X、Y
graphics.drawString(number, 6 + i * 13,16);
codeNumbers += number;
}
// 绘制干扰线
public void drawNoise(Graphics graphics, int lineNumber)
{
graphics.setColor(getRandColor(160,200));
for (int i = 0; i < lineNumber; i++)
{
int pointX1 = 1 + (int)(Math.random() * width);
int pointY1 = 1 + (int)(Math.random() * height);
int pointX2 = 1 + (int)(Math.random() * width);
int pointY2 = 1 + (int)(Math.random() * height);
graphics.drawLine(pointX1, pointY1, pointX2, pointY2);
}
}
public 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);
}
// 处理 HTTP post 请求, 和doGet一样
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
doGet(request, response);
}
}
<%@ 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>servlet生成验证码</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="styles.css">
-->
<script type="text/javascript">
function refreshcode(){
document.getElementById("code").src="servlet/CodeMakerServlet?a="+Math.random()+100;
return false;
}
</script>
</head>
<body>
(servlet页面生成验证码)<br/><br/>
<form method=post action="check.jsp">
用户名：<input type="text" name="userName" size="15" value=""><br>
密码：<input type="text" name="password" size="15" value=""><br>
验证码：<input type="text" size="4" maxlength="4" name="rand"/>
<img id="code" src="servlet/CodeMakerServlet" title="看不清点击刷新验证码" style="cursor : pointer;" onclick="return refreshcode()"/>
<input type=submit value="提交">
</form>
</body>
</html>
