How to implement web page verification code function in Java-javaTutorial-php.cn

How to implement web page verification code function in Java

黄舟

Release： 2017-10-11 10:03:22

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This article mainly introduces the Java web page verification code function in detail, which has certain reference value. Interested friends can refer to it.

The example in this article shares the Java web page verification code with everyone. The implementation code is for your reference. The specific content is as follows

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());
 
 
 }
}

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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(&#39;src&#39;, &#39;yanCode?ts=&#39; + new Date().getTime());
 
  }
 </script>
 </body>
</html>

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