Servlet 验证码

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package com.check;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Check extends HttpServlet {

public Color getRandColor(int fc,int bc){
     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);
     }
public void doGet(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);



     try{


         int width=60,height=20;
         BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
         OutputStream os=response.getOutputStream();
         Graphics g=image.getGraphics();
         Random random=new Random();
         g.setColor(getRandColor(200,250));
         g.fillRect(0,0,width,height);
         g.setFont(new Font("Times New Roman",Font.PLAIN,18));
         g.setColor(getRandColor(160,200));
         for(int i=0;i<155;i++){
         int x=random.nextInt(width);
         int y=random.nextInt(height);
         int x1=random.nextInt(12);
         int y1=random.nextInt(12);
         g.drawLine(x,y,x+x1,y+y1);
         }
         String sRand="";
         for(int i=0;i<4;i++){
         String rand=String.valueOf(random.nextInt(10));
         sRand+=rand;
         g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
         g.drawString(rand,13*i+6,16);
         }
        request.getSession().setAttribute("rand", sRand);
        g.dispose();
         ImageIO.write(image,"JPEG",os);
         os.flush();
         os.close();
         os=null;

     }

         catch(Exception e){
         e.printStackTrace();
         }
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}

}

package com.check;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Login extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

this.doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
String code=request.getParameter("code");
String rand=(String)request.getSession().getAttribute("rand");
if(!code.equals(rand)){
  request.setAttribute("error", "验证码错误");
  request.getRequestDispatcher("/Chec.jsp").forward(request, response);

  return;
}
request.getRequestDispatcher("/Succ.jsp").forward(request, response);
}

}

<%@ page language="java" import="java.util.*,java.sql.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<script src="js/jquery-1.6.4.js" type="text/javascript">

</script>
<script language="javascript">
function loadimage(){
document.getElementById("randImage").src="Check?"+Math.random();
}

</script>

    <base href="<%=basePath%>">

    <title>My JSP 'Register.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

</head>

<body>
   <form action="Login" method="post">
   <table>
<tr><td><input type="text" id="te" name="code"/></td><td><img alt="code" id="randImage" src="Check" width="60" height="20" border="1" align="absmiddle"/> </td></tr>
   <tr><td height="36" colspan="2" align="center" valign="middle"><a href="javascript:loadimage();"><font>看不清</font></a></td></tr>
   </table>
   <div>${error }</div>
   <input type="submit" id="bt" value="提交 "/>


   </form>
</body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>email</servlet-name>
    <servlet-class>com.email.Email</servlet-class>
</servlet>
<servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>check</servlet-name>
    <servlet-class>com.check.Check</servlet-class>
</servlet>
<servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>login</servlet-name>
    <servlet-class>com.check.Login</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>email</servlet-name>
    <url-pattern>/Email</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>check</servlet-name>
    <url-pattern>/Check</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>login</servlet-name>
    <url-pattern>/Login</url-pattern>
</servlet-mapping>
<welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>

过滤器

package com.movie;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;public class Chin implements Filter{public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {request.setCharacterEncoding("utf-8");chain.doFilter(request, response);}public void init(FilterConfig filterConfig) throws ServletException {}}

<filter>  <filter-name>encode</filter-name>   <filter-class>com.movie.Chin</filter-class>      </filter> <filter-mapping>  <filter-name>encode</filter-name>   <url-pattern>/*</url-pattern>   </filter-mapping>