java web 实现验证码 

  1 1.编写数字、英文随机生成的 server 类，源码：
  2 package com;
  3 
  4 import java.awt.Color;
  5 import java.awt.Font;
  6 import java.awt.Graphics;
  7 import java.awt.image.BufferedImage;
  8 import java.io.ByteArrayOutputStream;
  9 import java.io.IOException;
 10 import java.io.PrintWriter;
 11 
 12 import javax.imageio.ImageIO;
 13 import javax.servlet.ServletException;
 14 import javax.servlet.ServletOutputStream;
 15 import javax.servlet.http.HttpServlet;
 16 import javax.servlet.http.HttpServletRequest;
 17 import javax.servlet.http.HttpServletResponse;
 18 import javax.servlet.http.HttpSession;
 19 
 20 public class logcheck extends HttpServlet {
 21 
 22     public logcheck() {
 23         super();
 24     }
 25 
 26     
 27     public void destroy() {
 28         super.destroy(); 
 29     }
 30 
 31     public void doGet(HttpServletRequest request, HttpServletResponse response)
 32             throws ServletException, IOException {
 33 
 34         doPost(request, response);
 35     }
 36 
 37 
 38     /*实现的核心代码*/
 39     public void doPost(HttpServletRequest request, HttpServletResponse response)
 40             throws ServletException, IOException {
 41 
 42         response.setContentType("image/jpeg");
 43         HttpSession session=request.getSession();
 44         int width=60;
 45         int height=20;
 46         
 47         //设置浏览器不要缓存此图片
 48         response.setHeader("Pragma", "No-cache");
 49         response.setHeader("Cache-Control", "no-cache");
 50         response.setDateHeader("Expires", 0);
 51         
 52         //创建内存图像并获得图形上下文
 53         BufferedImage image=new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
 54         Graphics g=image.getGraphics();
 55         
 56         /*
 57          * 产生随机验证码
 58          * 定义验证码的字符表
 59          */
 60         String chars="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 61         char[] rands=new char[4];
 62         for(int i=0;i<4;i++){
 63             int rand=(int) (Math.random() *36);
 64             rands[i]=chars.charAt(rand);
 65         }
 66         
 67         /*
 68          * 产生图像
 69          * 画背景
 70          */
 71         g.setColor(new Color(0xDCDCDC));
 72         g.fillRect(0, 0, width, height);
 73         
 74         /*
 75          * 随机产生120个干扰点
 76          */
 77         
 78         for(int i=0;i<120;i++){
 79             int x=(int)(Math.random()*width);
 80             int y=(int)(Math.random()*height);
 81             int red=(int)(Math.random()*255);
 82             int green=(int)(Math.random()*255);
 83             int blue=(int)(Math.random()*255);
 84             g.setColor(new Color(red,green,blue));
 85             g.drawOval(x, y, 1, 0);
 86         }
 87         g.setColor(Color.BLACK);
 88         g.setFont(new Font(null, Font.ITALIC|Font.BOLD,18));
 89         
 90         //在不同高度输出验证码的不同字符
 91         g.drawString(""+rands[0], 1, 17);
 92         g.drawString(""+rands[1], 16, 15);
 93         g.drawString(""+rands[2], 31, 18);
 94         g.drawString(""+rands[3], 46, 16);
 95         g.dispose();
 96         
 97         //将图像传到客户端
 98         ServletOutputStream sos=response.getOutputStream();
 99         ByteArrayOutputStream baos=new ByteArrayOutputStream();
100         ImageIO.write(image, "JPEG", baos);
101         byte[] buffer=baos.toByteArray();
102         response.setContentLength(buffer.length);
103         sos.write(buffer);
104         baos.close();
105         sos.close();
106         
107         session.setAttribute("checkcode", new String(rands));
108     }
109 
110     
111     public void init() throws ServletException {
112         // Put your code here
113     }
114 
115 }
116 
117 2.用于显示验证码的页面：
118 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
119 <%
120 String path = request.getContextPath();
121 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
122 %>
123 
124 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
125 <html>
126   <head>
127     <base href="<%=basePath%>">
128     
129     <title>index</title>
130     <meta http-equiv="pragma" content="no-cache">
131     <meta http-equiv="cache-control" content="no-cache">
132     <meta http-equiv="expires" content="0">    
133     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
134     <meta http-equiv="description" content="This is my page">
135     <!--
136     <link rel="stylesheet" type="text/css" href="styles.css">
137     -->
138   </head>
139   
140   <body>
141   <form action="yanzheng" method="post">
142       <input type="text" name="name" size="5" maxlength="4">
143     <a href="index.jsp"><img border="0" src="logcheck"></a><br><br>
144     &nbsp&nbsp&nbsp&nbsp&nbsp<input type="submit" value="提交">
145   </form>
146   </body>
147 </html>
148 3.用于检验输入的验证码是否正确：
149 package com;
150 
151 import java.io.IOException;
152 import java.io.PrintWriter;
153 
154 import javax.jms.Session;
155 import javax.servlet.ServletException;
156 import javax.servlet.http.HttpServlet;
157 import javax.servlet.http.HttpServletRequest;
158 import javax.servlet.http.HttpServletResponse;
159 import javax.servlet.http.HttpSession;
160 
161 public class yanzheng extends HttpServlet {
162 
163     public yanzheng() {
164         super();
165     }
166 
167     public void destroy() {
168         super.destroy(); 
169     }
170 
171     public void doGet(HttpServletRequest request, HttpServletResponse response)
172             throws ServletException, IOException {
173 
174         doPost(request, response);
175     }
176     /*核心代码*/
177     public void doPost(HttpServletRequest request, HttpServletResponse response)
178             throws ServletException, IOException {
179 
180         String info=null;
181         /*获取输入的值*/
182         String value1=request.getParameter("name");
183 
184         /*获取图片的值*/
185         HttpSession session=request.getSession();
186         String value2=(String)session.getAttribute("checkcode");
187 
188         /*对比两个值（字母不区分大小写）*/
189         if(value2.equalsIgnoreCase(value1)){
190             info="验证码输入正确";
191         }else{
192             info="验证码输入错误";
193         }
194         System.out.println(info);
195         request.setAttribute("info", info);
196         request.getRequestDispatcher("/login.jsp").forward(request, response);
197     }
198 
199     
200     public void init() throws ServletException {
201         // Put your code here
202     }
203 
204 }
205 4.显示输入结构界面（输入验证码是否正确）：
206 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
207 <%
208 String path = request.getContextPath();
209 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
210 %>
211 
212 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
213 <html>
214   <head>
215     <base href="<%=basePath%>">
216     
217     <title>My JSP 'login.jsp' starting page</title>
218     
219     <meta http-equiv="pragma" content="no-cache">
220     <meta http-equiv="cache-control" content="no-cache">
221     <meta http-equiv="expires" content="0">    
222     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
223     <meta http-equiv="description" content="This is my page">
224     <!--
225     <link rel="stylesheet" type="text/css" href="styles.css">
226     -->
227 
228   </head>
229   
230   <body>
231     <%=request.getAttribute("info") %>
232   </body>
233 </html>
234 5.项目结构、效果截图：




 








            

            
posted @ 
2016-06-21 15:15 
烟雨观春柳 
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