简单的验证码实现
程序员文章站
2022-05-24 21:07:45
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前端界面代码如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<img alt="验证码" src="/shopping/YZM" title="看不清楚，换一张" onclick="change(this)">
</body>
</html>
<script type="text/javascript">
function change(obj) {
obj.src="/shopping/YZM?time"+Math.random();
}
</script>
servlet中的代码如下：
package com.lhc.Servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
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 YZMServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
// 使用java图形界面技术绘制一张图片
int width = 30 * 4;
int height = 30;
// 1. 创建一张内存图片
BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 2.获得绘图对象
Graphics graphics = bufferedImage.getGraphics();
// 3、绘制背景颜色
graphics.setColor(Color.LIGHT_GRAY);
graphics.fillRect(0, 0, width, height);
// 4、绘制图片边框
graphics.setColor(Color.LIGHT_GRAY);
graphics.drawRect(0, 0, width - 1, height - 1);
// 5、输出验证码内容
graphics.setColor(Color.BLACK);
graphics.setFont(new Font("宋体", Font.BOLD, 20));
// 随机输出4个字符
Graphics2D graphics2d = (Graphics2D) graphics;
String s = "ABCDEFGHGKLMNPQRSTUVWXYZ23456789";
Random random = new Random();
//session中要用到
String msg="";
int x = 5;
for (int i = 0; i < 4; i++) {
int index = random.nextInt(32);
String content = String.valueOf(s.charAt(index));
msg+=content;
double theta = random.nextInt(45) * Math.PI / 180;
//让字体扭曲
graphics2d.rotate(theta, x, 18);
graphics2d.drawString(content, x, 18);
graphics2d.rotate(-theta, x, 18);
x += 30;
}
// 6、绘制干扰线
graphics.setColor(Color.GRAY);
for (int i = 0; i < 3; i++) {
int x1 = random.nextInt(width)-50;
int x2 = random.nextInt(width)-50;
int y1 = random.nextInt(height);
int y2 = random.nextInt(height);
graphics.drawLine(x1, y1, x2, y2);
}
// 释放资源
graphics.dispose();
// 图片输出 ImageIO
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
}