web项目 验证码 *** 最爱那水货

1. jsp代码 ：

<Script>
    function changeImg(){
                document.getElementById("certImg").src ="makeCertPic.jsp?it="+Math.random();  /* +Math.random() */
            }
</Script>



                        <table width="100%" border="0" cellspacing="1" cellpadding="1">
                            <tr>
                                <td width="5%">&nbsp;</td>
                                <td nowrap width="11%" align="left" class="loginname">验证码：

                                </td>
                                <td nowrap width="68%" class="loginname">
                                    <div align="left">
                                        <input type="text" istyle="input01" name="certCode"
                                            class="input01" />
                                        <!-- <iframe width="200" height="60" id="certImg" src="makeCertPic.jsp"></iframe> -->
                                        <img id="certImg" src="makeCertPic.jsp" onclick="changeImg()" alt="看不清换一张">
                                        <!-- onclick="changeImg()" alt="看不清换一张" -->

                                    </div>

                                </td>

                            </tr>

                            <tr>
                                <td width="14%">&nbsp;</td>

                                <td nowrap width="18%" align="right" class="loginname">
                                    <div align="left">用户名：</div>
                                </td>
                                <td nowrap width="68%" class="loginname">
                                    <div align="left">
                                        <html:text styleClass="input01" property="user_code"
                                            onkeypress="return handleEnter(this, event,1)" />
                                        <!-- <a href="#" onclick="changeImg()">看不清换一张 </a> -->
                                    </div>
                                </td>
                            </tr>
                            <tr>
                                <td width="14%">&nbsp;</td>
                                <td nowrap width="18%" align="right" class="loginname">
                                    <div align="left">密&nbsp;&nbsp;码：</div>
                                </td>
                                <td nowrap width="68%" class="loginname">
                                    <div align="left">
                                        <html:password styleClass="input01" property="password"
                                            value="" />
                                    </div>
                                </td>

                            </tr>

                            <tr>


                                <td align="left">
                                <td nowrap align="right"><html:submit value='登　录'
                                        styleClass="button" onclick="return ck_login();" /></td>
                                <td nowrap align="left"><html:reset value='重　写'
                                        styleClass="button" /></td>
                                </td>
                            </tr>
                        </table>

2.链接的加jsp文件，用于加载验证码数据

<%@page import="com.test.makeCertPic"%>
<%@ page language="java" import="java.util.*" pageEncoding="GBK"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@page contentType="image/jpeg" %>

 <%
     makeCertPic pic = new makeCertPic();
     String str = pic.getCertPic(0, 0, response.getOutputStream());
     session.setAttribute("certCode", str);
     //关闭response ，不加会运行两次，且会报错
     out.clear();  
     out = pageContext.pushBody(); 
 %>

3.对应的验证码类 java代码

package com.test;

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.util.Random;
import javax.imageio.ImageIO;

/**
 * @author dzy 生成验证码图片
 */
public class makeCertPic {
    // 验证码图片中可以出现的字符集，可根据需要修改
    private char mapTable[] = { '0','1', '2', '3', '4', '5', '6', '7', '8','9' };

    /**
     * 功能:生成彩色验证码图片 参数width为生成图片的宽度,参数height为生成图片的高度,参数os为页面的输出流
     */
    public String getCertPic(int width, int height, OutputStream os) {
        if (width <= 0)
            width = 60;
        if (height <= 0)
            height = 20;
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        Graphics g = image.getGraphics();
        // 设定背景色
        g.setColor(new Color(0xDCDCDC));
        g.fillRect(0, 0, width, height);
        // 画边框
        g.setColor(Color.black);
        g.drawRect(0, 0, width - 1, height - 1);
        // 取随机产生的认证码
        String strEnsure = "";
        // 4代表4位验证码,如果要生成更多位的认证码,则加大数值
        for (int i = 0; i < 4; ++i) {
            strEnsure += mapTable[(int) (mapTable.length * Math.random())];
        }
        // 将认证码显示到图像中,如果要生成更多位的认证码,增加drawString语句
        g.setColor(Color.black);
        g.setFont(new Font("Atlantic Inline", Font.PLAIN, 18));
        String str = strEnsure.substring(0, 1);
        g.drawString(str, 8, 17);
        str = strEnsure.substring(1, 2);
        g.drawString(str, 20, 15);
        str = strEnsure.substring(2, 3);
        g.drawString(str, 35, 18);
        str = strEnsure.substring(3, 4);
        g.drawString(str, 45, 15);
        // 随机产生10个干扰点
        Random rand = new Random();
        for (int i = 0; i < 10; i++) {
            int x = rand.nextInt(width);
            int y = rand.nextInt(height);
            g.drawOval(x, y, 1, 1);
        }
        // 释放图形上下文
        g.dispose();
        try {
            // 输出图像到页面 
            ImageIO.write(image, "JPEG", os);
        } catch (IOException e) {
            return "";
        }
        return strEnsure;
    }
}

项目中的 验证码 尤其注意登陆时会被项目的filter类过滤排除，导致验证码加载不出来 ，需要在web.xml中 进行jsp的自定义过滤

 本项目中设置filter的xml文件 和 过滤的java代码如下：

    <filter>
        <filter-name>BtSystemFilter</filter-name>
        <filter-class>com.bettersoft.filters.BtSystemFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>BtSystemFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;
         HttpSession session = request.getSession();
        String uri = request.getRequestURI();    
         String projectName = request.getContextPath();
         String url=uri.substring(projectName.length());
        try
        {  
            if( uri.startsWith(projectName + "/services")
                    || uri.startsWith(projectName + "/axis2-web"))                //webservice
            {
                chain.doFilter(req, resp);
                }
              //过滤.jsp和.do
            else if (uri.endsWith(".jsp")|| uri.endsWith(".do"))
            { 
             //如果为系统登录类型资源不进行session检查    
             if((uri.equals(projectName+"/index.jsp"))
                 ||uri.equals(projectName+"/login.jsp")
                 ||uri.equals(projectName+"/main.jsp")
                 ||uri.equals(projectName+"/login.do")
                 ||uri.equals(projectName+"/showTRCA.jsp")//用证书登录时选择证书
                 ||uri.equals(projectName+"/bindCA.jsp")//用证书登录时绑定证书
                 ||uri.equals(projectName+"/error.jsp")
                 ||uri.equals(projectName+"/makeCertPic.jsp")//验证码
                 )
             {
                 chain.doFilter(req, resp); 
             }    
             else
             {   //session失效或未登录
                 if (session.getAttribute("com.bettersoft.admin.userbean") == null)
                 { response.sendRedirect(projectName + "/login.jsp?nologin=nologin");
                  }
                 else
                 {   //如果当前资源是系统菜单
                     if(CheckUserUtil.isSyeRes(url))
                     {  
                        if(CheckUserUtil.hasPermission(request, url))
                        {
                            chain.doFilter(req, resp);
                        }
                        else
                        {
                            response.sendRedirect(projectName + "/login.jsp?nologin=invalidurl");    
                        }    
                     }    
                     else
                     {
                         chain.doFilter(req, resp);     
                     }     
                      
                 }     
             }     
            }else
            {    
            chain.doFilter(req, resp); 
            }
         }
        catch(Exception e)
        {    e.printStackTrace();
             String  errormsg="未知的系统异常";
             if(e.getMessage()!=null)
                 {
                 //if(e.getMessage().length()<50)
                 errormsg=e.getMessage();
                 }
             request.setAttribute("errormsg",errormsg);
             request.getRequestDispatcher("/error.jsp").forward(request, response);
        }
    }

最后的效果图