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JavaWeb项目--网上商城（6-1）附随机验证码的实现

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>testUser</display-name>
  <servlet>
    <servlet-name>VerifyCodeServlet</servlet-name>
    <servlet-class>cn.itcast.vcode.servlet.VerifyCodeServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>cn.itcast.test.web.servlet.LoginServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>VerifyCodeServlet</servlet-name>
    <url-pattern>/VerifyCodeServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/LoginServlet</url-pattern>
  </servlet-mapping>
  
  <!-- 处理全站请求编码，无论是GET还是POST，默认是UTF-8 -->
  <filter>
      <filter-name>EncodingFilter</filter-name>
      <filter-class>cn.itcast.filter.EncodingFilter</filter-class>
      <init-param>
          <param-name>charset</param-name>
          <param-value>utf-8</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>EncodingFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'form.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">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
<script type="text/javascript">
    function _hyz() {
        /*
        1. 获取<img>元素
        2. 给它的src指向为/tools/VerifyCodeServlet
        */
        var img = document.getElementById("imgVerifyCode");
        // 需要给出一个参数，这个参数每次都不同，这样才能干掉浏览器缓存！
        img.src = "/testUser/VerifyCodeServlet?a=" + new Date().getTime();
    }
</script>
  </head>
  
  <body>
<%--
1. 写表单，其中包含图片（验证码）
2. 让图片显示出来：
　　把<img>的src指向VerifyCodeServlet，你需要在web.xml中部署VerfiyCodeServlet
3. 换一张
--%>
<form action="/testUser/LoginServlet" method="post">
    <%-- 添加一个参数：method=login --%>
    <input type="hidden" name="method" value="login">
用户名：<input type="text"  name="name"/><br/>
密　码：<input type="password" name="pwd"/><br/>
验证码：<input type="text" name="verifyCode"/><br/>
<img src="/testUser/VerifyCodeServlet" id="imgVerifyCode"/>
<a href="javascript:_hyz()">换一张</a>
<br/>
<input type="submit" value="提交"/>
</form>
  </body>
</html>

package cn.itcast.test.web.servlet;

import java.io.IOException;

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

import cn.itcast.servlet.BaseServlet;

public class LoginServlet extends BaseServlet {

    public String login(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        /*
         * 校验验证码
         * 1. 获取表单中的验证码
         * 2. 获取图片上的文字
         */
        String verifyCode = request.getParameter("verifyCode");
        // VerifyCodeServlet会把真正的验证码保存到session中
        String vcode = (String) request.getSession().getAttribute("vCode");
        System.out.println(verifyCode.equalsIgnoreCase(vcode));
        
        return "/form.jsp";
    }
}

第二种实现二维码验证

package com.atguigu.javaweb;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CheckCodeServlet extends HttpServlet {
    
    private static final long serialVersionUID = 1L;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        //1. 获取请求参数: CHECK_CODE_PARAM_NAME
        String paramCode = request.getParameter("CHECK_CODE_PARAM_NAME");
        
        //2. 获取 session 中的 CHECK_CODE_KEY 属性值
        String sessionCode = (String)request.getSession().getAttribute("CHECK_CODE_KEY");
        
        System.out.println(paramCode);
        System.out.println(sessionCode); 
        
        //3. 比对. 看是否一致, 若一致说明验证码正确, 若不一致, 说明验证码错误
        if(!(paramCode != null && paramCode.equals(sessionCode))){
            request.getSession().setAttribute("message", "验证码不一致!");
            response.sendRedirect(request.getContextPath() + "/index.jsp");
            return;
        }
        
        System.out.println("受理请求!");
        
    }

}

package com.atguigu.javaweb; 

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

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

public class ValidateColorServlet extends HttpServlet {

    public static final String CHECK_CODE_KEY = "CHECK_CODE_KEY";
    
    private static final long serialVersionUID = 1L;
    
    //设置验证图片的宽度, 高度, 验证码的个数
    private int width = 152;
    private int height = 40;
    private int codeCount = 6;
    
    //验证码字体的高度
    private int fontHeight = 4;
    
    //验证码中的单个字符基线. 即：验证码中的单个字符位于验证码图形左上角的 (codeX, codeY) 位置处
    private int codeX = 0;
    private int codeY = 0;
    
    //验证码由哪些字符组成
    char [] codeSequence = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz23456789".toCharArray();
    
    //初始化验证码图形属性
    public void init(){
        fontHeight = height - 2;
        codeX = width / (codeCount + 2);
        codeY = height - 4;
    }

    public void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //定义一个类型为 BufferedImage.TYPE_INT_BGR 类型的图像缓存
        BufferedImage buffImg = null;
        buffImg = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
    
        //在 buffImg 中创建一个 Graphics2D 图像
        Graphics2D graphics = null;
        graphics = buffImg.createGraphics();
        
        //设置一个颜色, 使 Graphics2D 对象的后续图形使用这个颜色
        graphics.setColor(Color.WHITE);
        
        //填充一个指定的矩形: x - 要填充矩形的 x 坐标; y - 要填充矩形的 y 坐标; width - 要填充矩形的宽度; height - 要填充矩形的高度
        graphics.fillRect(0, 0, width, height);
        
        //创建一个 Font 对象: name - 字体名称; style - Font 的样式常量; size - Font 的点大小
        Font font = null;
        font = new Font("", Font.BOLD, fontHeight);
        //使 Graphics2D 对象的后续图形使用此字体
        graphics.setFont(font);
        
        graphics.setColor(Color.BLACK);
        
        //绘制指定矩形的边框, 绘制出的矩形将比构件宽一个也高一个像素
        graphics.drawRect(0, 0, width - 1, height - 1);
        
        //随机产生 15 条干扰线, 使图像中的认证码不易被其它程序探测到
        Random random = null;
        random = new Random();
        graphics.setColor(Color.GREEN);
        for(int i = 0; i < 55; i++){
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int x1 = random.nextInt(20);
            int y1 = random.nextInt(20);
            graphics.drawLine(x, y, x + x1, y + y1);
        }
        
        //创建 randomCode 对象, 用于保存随机产生的验证码, 以便用户登录后进行验证
        StringBuffer randomCode;
        randomCode = new StringBuffer();
        
        for(int i = 0; i < codeCount; i++){
            //得到随机产生的验证码数字
            String strRand = null;
            strRand = String.valueOf(codeSequence[random.nextInt(36)]);
            
            //把正在产生的随机字符放入到 StringBuffer 中
            randomCode.append(strRand);
            
            //用随机产生的颜色将验证码绘制到图像中
            graphics.setColor(Color.BLUE);
            graphics.drawString(strRand, (i + 1)* codeX, codeY);
        }
        
        //再把存放有所有随机字符的 StringBuffer 对应的字符串放入到 HttpSession 中
        request.getSession().setAttribute(CHECK_CODE_KEY, randomCode.toString());
        
        //禁止图像缓存
        response.setHeader("Pragma", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        
        //将图像输出到输出流中
        ServletOutputStream sos = null;
        sos = response.getOutputStream();
        ImageIO.write(buffImg, "jpeg", sos); 
        sos.close();
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>Validate</display-name>
  <servlet>
    <servlet-name>validateColorServlet</servlet-name>
    <servlet-class>com.atguigu.javaweb.ValidateColorServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>validateColorServlet</servlet-name>
    <url-pattern>/validateColorServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>CheckCodeServlet</display-name>
    <servlet-name>CheckCodeServlet</servlet-name>
    <servlet-class>com.atguigu.javaweb.CheckCodeServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>CheckCodeServlet</servlet-name>
    <url-pattern>/checkCodeServlet</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    
  </welcome-file-list>
</web-app>

<%@page import="java.util.Date"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>

    <font color="red">
        <%= session.getAttribute("message") == null ? "" : session.getAttribute("message")%>
    </font>
    <form action="<%= request.getContextPath() %>/checkCodeServlet" method="post">
        name: <input type="text" name="name"/>
        checkCode: <input type="text" name="CHECK_CODE_PARAM_NAME"/> 
        <a href="javascript:getImger()">换一张</a>
        <img alt="" src="<%= request.getContextPath() %>/validateColorServlet"  id="ims"> 
        <input type="submit" value="Submit"/>
    </form>
    
</body>
<script type="text/javascript">
    function  getImger(){
        var img=document.getElementById("ims");
        img.src="<%= request.getContextPath() %>/validateColorServlet?a="+new Date().getTime();
    }

</script>
</html>

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原文地址：https://www.cnblogs.com/ou-pc/p/7911718.html

JavaWeb项目--网上商城 （6-1）附随机验证码的实现

JavaWeb项目--网上商城（6-1）附随机验证码的实现