动态生成验证码案例（Java）
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servlet代码
package cn.guizimo.web.servlet;
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("/checkCode")
public class CheckCode extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
int width = 100;
int height = 50;
//创建图片对象
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
//美化
Graphics g = image.getGraphics();
//背景
g.setColor(Color.PINK);
g.fillRect(0, 0, width, height);
//边框
g.setColor(Color.BLUE);
g.drawRect(0, 0, width - 1, height - 1);
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
Random ran = new Random();
for (int i = 1; i <= 4; i++) {
int index = ran.nextInt(str.length());
char ch = str.charAt(index);
g.drawString(ch+"",width/5*i,height/2);
}
//干扰线
g.setColor(Color.GREEN);
for (int i = 0; i < 10; i++) {
int x1 = ran.nextInt(width);
int x2= ran.nextInt(width);
int y1 = ran.nextInt(height);
int y2 = ran.nextInt(height);
g.drawLine(x1,y1,x2,y2);
}
//输出图片到浏览器
ImageIO.write(image, "jpg", resp.getOutputStream());
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doPost(req, resp);
}
}
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script>
window.onload = function () {
var img = document.getElementById("checkCode");
img.onclick = function () {
var data = new Date().getTime();
img.src = "/tomcat_test_war_exploded/checkCode?" + data;
}
}
</script>
</head>
<body>
<img id="checkCode" src="/tomcat_test_war_exploded/checkCode"/>
</body>
</html>
启动项目
点击图片可以切换验证码
感谢
黑马程序员
万能的网络
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