java 验证码彩色验证码

最新推荐文章于 2025-09-10 22:21:01 发布

l8693946

最新推荐文章于 2025-09-10 22:21:01 发布

阅读量573

点赞数

CC 4.0 BY-SA版权

文章标签： java servlet import random string image

本文链接：https://blog.youkuaiyun.com/l8693946/article/details/1931737

本文介绍了一个使用Java生成并验证验证码图片的方法。该方法通过在内存中创建图像、添加随机干扰线和数字来生成验证码，并将其保存在HTTP会话中进行后续验证。用户通过输入验证码与服务器端保存的验证码进行对比，实现简单的安全性验证。

package untitled1;

import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;
import javax.imageio.*;
/**
*
* @author http://www.tot.name
* @version
*/
public class Image extends HttpServlet {

/** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg");
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
HttpSession session=request.getSession();
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 获取图形上下文
Graphics g = image.getGraphics();

// 生成随机类
Random random = new Random();

// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);

// 设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));

// 画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);

// 随机产生 155 条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}

// 取随机产生的认证码 (4 位数字 )
String sRand="";
for (int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
// 将认证码显示到图象中
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand,13*i+6,16);
}

// 将认证码存入 SESSION
session.setAttribute("rand",sRand);
// 图象生效
g.dispose();
ServletOutputStream responseOutputStream =response.getOutputStream();
// 输出图象到页面
ImageIO.write(image, "JPEG", responseOutputStream);

// 以下关闭输入流！
responseOutputStream.flush();
responseOutputStream.close();
}
Color getRandColor(int fc,int bc){// 给定范围获得随机颜色
Random random = new Random();
if(fc>255) fc=255;
if(bc>255) bc=255;
int r=fc+random.nextInt(bc-fc);
int g=fc+random.nextInt(bc-fc);
int b=fc+random.nextInt(bc-fc);
return new Color(r,g,b);
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/** Handles the HTTP <code>GET</code> method.
* @param request servlet request
* @param response servlet response
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}

/** Handles the HTTP <code>POST</code> method.
* @param request servlet request
* @param response servlet response
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}

/** Returns a short description of the servlet.
*/
public String getServletInfo() {
return "Short description";
}
// </editor-fold>
}

--------------- 使用验证码图片的文件 ---------index.jsp------------------------------------

<%@ page contentType="text/html;charset=gb2312" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title> 认证码输入页面 </title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head>
<body>
<form method=post action="check.jsp">
<table>
<tr>
<td align=left> 系统产生的认证码： </td>
<td><img border=0 src="http://www.zhmy.com/image"></td>
</tr>
<tr>
<td align=left> 输入上面的认证码： </td>
<td><input type=text name=rand maxlength=4 value=""></td>
</tr>
<tr>
<td colspan=2 align=center><input type=submit value=" 提交检测 "></td>
</tr>
</form>
</body>
</html>

----------------- 验证的页面 ----------check.jsp------------------------------

<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<html>
<head>
<title> 认证码验证页面 </title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head>

<body>
<%
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
%>
系统产生的认证码为： <%= rand %><br>
您输入的认证码为： <%= input %><br>
<br>
<%
if (rand.equals(input)) {
%>
<font color=green> 输入相同，认证成功！ </font>
<%
} else {
%>
<font color=red> 输入不同，认证失败！ </font>
<%
}
%>
</body>
</html>