JavaWeb 实现简单的验证码
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后端
package cn.itcast.web.servlet;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
int width = 100;
int height = 50;
//1.创建一对象，在内存中图片(验证码图片对象)
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//2.美化图片
//2.1 填充背景色
Graphics g = image.getGraphics();//画笔对象
g.setColor(Color.PINK);//设置画笔颜色
g.fillRect(0, 0, width, height);
//2.2画边框
g.setColor(Color.BLUE);
g.drawRect(0, 0, width - 1, height - 1);
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
//生成随机角标
Random ran = new Random();
for (int i = 1; i <= 4; i++)
int index = ran.nextInt(str.length());
//获取字符
char ch = str.charAt(index);//随机字符
//2.3写验证码
g.drawString(ch + "", width / 5 * i, height / 2);
//2.4画干扰线
g.setColor(Color.GREEN);
//随机生成坐标点
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);
//3.将图片输出到页面展示
ImageIO.write(image, "jpg", response.getOutputStream());
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
this.doPost(request, response);
前端
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script>
/*
分析：
点击超链接或者图片，需要换一张
1.给超链接和图片绑定单击事件
2.重新设置图片的src属性值
*/
window.onload = function ()
//1.获取图片对象
var img = document.getElementById("checkCode");
//2.绑定单击事件
img.onclick = function ()
//加时间戳
var date = new Date().getTime();
img.src = "/项目名/checkCodeServlet?" + date;
function f()
var img = document.getElementById("checkCode");
var date = new Date().getTime();
img.src = "/项目名/checkCodeServlet?" + date;
</script>
</head>
<body>
<img id="checkCode" src="/项目名/checkCodeServlet"/>
<a href="javascript:void(0);" onclick="f()">看不清换一张？</a>
</body>
</html>
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