这篇文章主要为大家详细介绍了java实现网页验证码功能，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
本文实例为大家分享了java网页验证码的实现代码，供大家参考，具体内容如下
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="width: 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>
以上就是java中网页验证码功能的实现方法的详细内容。