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: