Servlet | 用 Response 搞一个验证码

解释说明都在注释里面了，直接上代码：

package com.wzq.response;

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,height = 50;
        //1. 创建一个对象，在内存中生成图片（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);
        g.fillRect(0,0,width,height);

        //2.2 画边框
        g.setColor(Color.BLUE);
        g.drawRect(0,0,width-1,height-1);

        //2.3 生成随机字符
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
        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);
        }

        //2.4 画干扰线
        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);
        }

        //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);
    }
}

html页面：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>验证码</title>

    <script>
        window.onload = function () {
     
     
            var img = document.getElementById("checkCode");
            img.onclick = function () {
     
     
                var date = new Date().getTime();
                //加时间戳是为了不重复的请求资源
                img.src = "/ResponseDemo/checkCodeServlet?"+date;  
            }
        }
    </script>

</head>
<body>
    <img id="checkCode" src="/ResponseDemo/checkCodeServlet">
</body>
</html>

效果：
在这里插入图片描述

Servlet | 用 Response 搞一个验证码

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