《生成登录验证码V1.0》
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2024-03-20 13:46:58
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1.登录页面:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<!-- <script type="text/javascript">
function changeImg(){
document.getElementById("img").src="CheckCodeServlet?a="+Math.random();//new Date()
}
</script>
<body>
<form action="LoginServlet" method="post">
用户名:<input type="text" name = "usrename" /><br>
密码:<input type="password" name = "password" /><br>
验证码:<input type="text" name = "checkcode" size="10"/><img src="CheckCodeServlet"><a id="img" href="javascript:changeImg()">看不清,换一张?</a><br>
<input type="submit" value="登录">
</form> -->
<script >
function changeImg(){
//因为路径不变,会有缓存,所以?加上一个每次回变化的值:new Date();或者Math.random();带值并不影响访问路径,只是地址栏会发生变化,防止缓存
document.getElementById('checkcode').src="CheckCodeServlet?aaa="+Math.random();
}
</script>
</head>
<body>
<form action="LoginServlet" method = "get">
<font size="6">会员登录</font>
<font size = "2"> USER LOGIN</font><br/>
用户名:<input type="text" name = "username"><br/>
密码:<input type="password" name = "userpwd"><br/>
验证码:<input type="text" name = "checkcode" size="10"><img id="checkcode" src="CheckCodeServlet"><a href="javascript:changeImg()">看不清?换一张</a><br/>
<input type="submit" value="登录">
</form>
</body>
</html>2.生成验证码的Servlet
package com.offcn.servlet;
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.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CheckCodeServlet extends HttpServlet {
//图片是通过src的地址链接进行访问,所以是get请求
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.生成验证码图片的宽度和高度
int width=60;
int height=30;
//2.设置一个字符串,从字符串中随机抽取4个字符,放在验证码的图片上
String data = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
Random random = new Random();
//3创建一个图片
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//4获得画板
Graphics g = image.getGraphics();
//5 填充一个矩形
// * 设置颜色
g.setColor(Color.BLACK);
g.fillRect(0, 0, width, height);
g.setColor(Color.WHITE);
g.fillRect(1, 1, width-2, height-2);
// * 设置字体:宋体,加粗|用的什么字体,大小
g.setFont(new Font("宋体", Font.BOLD|Font.ITALIC, 25));
//6 写随机字
for(int i = 0 ; i < 4 ; i ++){
// 设置颜色--随机数
g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));
// 获得随机字
int index = random.nextInt(data.length());
String str = data.substring(index, index + 1);
// 写字符到图片上,左上位置
g.drawString(str, width/6 * (i + 1), 20);
}
//7 干扰线
for(int i = 0 ; i < 3 ; i ++){
// 设置颜色--随机数
g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));
// 随机绘制线:两点确定一条线,两个随机数确定一个坐标点
g.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width),random.nextInt(height));
// 随机点:两个随机数确定一个圆心,半径,粗细
g.drawOval(random.nextInt(width), random.nextInt(height), 2, 2);
}
//8end 将图片响应给浏览器
ImageIO.write(image, "jpg", response.getOutputStream());
}
}
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