Servlet:
package cn.bdqn.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.font.ImageGraphicAttribute;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet(name = "Servlet",urlPatterns = "/yanCode")
public class Servlet extends HttpServlet {
public void doPost(javax.servlet.http.HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request,response);
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String s="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
Random random = new Random();
int width=500;
int height=50;
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics graphics = image.getGraphics();//相当于画笔
//画背景
graphics.setColor(Color.gray);
graphics.fillRect(0,0,width,height);
graphics.setColor(Color.black);
for (int i = 0; i <4 ; i++) {
int index = random.nextInt(s.length());
String c = s.substring(index, index + 1);
graphics.drawString(c,width/5*(i+1),15);
}
ImageIO.write(image,"jpg",response.getOutputStream());
}
}
jsp:
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2017/10/10
Time: 13:04
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>验证码</title>
</head>
<body>
<img src="yanCode" alt="验证码" style=" 500px;height:50px">
<input type="button" value="看不清,更换验证码" id="btn" onclick="changeCode();">
<script type="text/javascript" src="js/jquery.min.js">
</script>
<script type="text/javascript" >
function changeCode() {
$("img").attr('src', 'yanCode?ts=' + new Date().getTime());
}
</script>
</body>
</html>