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java实现网页验证码功能

2019年07月19日  | 移动技术网IT编程  | 我要评论

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>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。

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