点击切换验证码
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet(urlPatterns = "/checkcode")
public class CheckCode extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
// 创建画布
int width = 120;
int height = 40;
BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 获得画笔
Graphics g = bufferedImage.getGraphics();
// 填充背景颜色
g.setColor(Color.white);
g.fillRect(0, 0, width, height);
// 绘制边框
g.setColor(Color.red);
g.drawRect(0, 0, width - 1, height - 1);
// 生成随机字符
// 准备数据
String data = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
// 准备随机对象
Random r = new Random();
// 声明一个变量 保存验证码
String code = "";
// 书写4个随机字符
for (int i = 0; i < 4; i++) {
// 设置字体
g.setFont(new Font("宋体", Font.BOLD, 28));
// 设置随机颜色
g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
String str = data.charAt(r.nextInt(data.length())) + "";
g.drawString(str, 10 + i * 28, 30);
// 将新的字符 保存到验证码中
code = code + str;
} //绘制干扰线
for (int i = 0; i < 6; i++) {
// 设置随机颜色
g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width),
r.nextInt(height));
} //将验证码 打印到控制台
System.out.println(code);
// 将验证码放到session中
request.getSession().setAttribute("code_session", code);
// 将画布显示在浏览器中
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
doGet(request, response);
}}
html代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script>
window.onload = function () {
var img = document.getElementById("img");
img.onclick = function () {
img.src = "/test/checkcode?r=" + new Date().getTime();
};
};
</script></head>
<body>
<form action="/test/login" method="post">
| 用户名 | <input type="text" name="username"/> |
| 密码 | <input type="password" name="password"/> |
| 验证码： | <input type="password" name="checkcode"/> |
| <input type="submit" value="登录"/> |
</form>
</body>
</html>