package 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("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width=100;
int height=50;
//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);
//美化图片
//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);
//画边框
g.setColor(Color.blue);
g.drawRect(0,0,width-1,height-1);
String str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
//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);
//写验证码
g.drawString(ch+"",width/5*i,height/2);
}
//画干扰线
g.setColor(Color.green);
for (int i = 0; i <10 ; i++) {
//随机生成坐标点
int x1 = ran.nextInt(width);
int x2 = ran.nextInt(width);
int y1 = ran.nextInt(height);
int y2 = ran.nextInt(height);
g.drawLine(x1,x2,y1,y2);
}
//将图片输出到页面显示
ImageIO.write(image,"jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script>
/**
* 点击超链接或图片，需要换一张
* 给超链接和图片绑定单击事件
* 重新设置图片的src属性值
*/
window.onload=function () {
//获取图片对象
let img = document.getElementById("checkCode");
//绑定单击事件
img.onclick=function () {
/**
* 因为浏览器会有默认缓存，如果路径不变，只会访问缓存，所以加date改变参数，保证每次都不同
* @type {number}
*/
//加时间戳
let date=new Date().getTime();
img.src="/day13_response/checkCodeServlet?"+date;
}
}
</script>
</head>
<body>
<img id="checkCode" src="/day13_response/checkCodeServlet"/>
</body>
</html>
