在servlet中实现验证码的功能

1:使用的工具

myeclipse2015
jdk1.8
tomcat8.0

2:目录结构

在这里插入图片描述

3:源码

index.jsp

<%@ page language="java" import="java.util.*" 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>
<base href="<%=basePath%>">

<title>My JSP 'index.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 reloadCode(){
			//设置一个时间的变量 已达到每次点击的时间不同 就进行加载
			var time = new Date().getTime();
			document.getElementById("imagecode").src="<%=request.getContextPath()%>/servlet/ImageServlet?d="+time;
		}
	</script>
</head>

<body>
	<form action="<%=request.getContextPath()%>/servlet/LoginServlet" method="get">
	验证码：
	<input type="text" name="checkcode" />
	<img id="imagecode" alt="验证码" src="<%=request.getContextPath()%>/servlet/ImageServlet" />
	<a href="javascript:reloadCode();">看不清楚</a>
	<br>
	<input type="submit" value="提交">
	</form>
</body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<servlet>
	<servlet-name>ImageServlet</servlet-name>
	<servlet-class>com.bi.ImageServlet</servlet-class>
</servlet>
<servlet>
	<servlet-name>LoginServlet</servlet-name>
	<servlet-class>com.bi.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
	<servlet-name>LoginServlet</servlet-name>
	<url-pattern>/servlet/LoginServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
	<servlet-name>ImageServlet</servlet-name>
	<url-pattern>/servlet/ImageServlet</url-pattern>
</servlet-mapping>

<welcome-file-list>
	<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

</web-app>

ImageServlet.java

package com.bi;

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

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

public class ImageServlet extends HttpServlet {
	
	//生成验证码的方法
	public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException{
		//图像数据缓冲区
		BufferedImage bi = new BufferedImage(68, 22, BufferedImage.TYPE_INT_RGB);//长，宽，类型
		//绘制图片
		Graphics g = bi.getGraphics();
		Color c = new Color(200,150,255);//对应RGB的颜色值
		//画颜色
		g.setColor(c);
		//画背景
		g.fillRect(0, 0, 68, 22);//坐标xy,长宽
		//定义一个含有字母和数字的字符串数组
		char[] ch = "ABCDEFGHIJKLMNOPKRSTUVWXYE0123456789".toCharArray();
		//定义一个用来保存的stringbufferd
		StringBuffer sb = new StringBuffer();
		//获取随机的4个组合
		Random r = new Random();
		int len = ch.length,index;
		for(int i =0 ;i<4;i++){
			index = r.nextInt(len);
			//获取一个随机颜色
			g.setColor(new Color(r.nextInt(88),r.nextInt(188),r.nextInt(255)));
			//把字符换到图片上
			g.drawString(ch[index] + "", i*15+3, 18);
			//用来保存字符
			sb.append(ch[index]);
		}
		//保存到session中为了待会验证
		request.getSession().setAttribute("piccode", sb.toString());
		//输出
		ImageIO.write(bi, "JPG", response.getOutputStream());
		
	}

}

LoginServlet.java

package com.bi;

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

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

public class LoginServlet extends HttpServlet {
	
	public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException{
		
		//从session中获取值
		String piccode = (String)request.getSession().getAttribute("piccode");
		//从input输入框中获取用户输入的
		String checkcode = request.getParameter("checkcode");
		//把所获取到的值变为大写
		checkcode = checkcode.toUpperCase();
		//返回类型
		response.setContentType("text/html;charset=UTF-8");
		//获取输出流
		PrintWriter out= response.getWriter();
		
		if(checkcode.equals(piccode)){
			out.print("验证码输入正确");
			out.print(checkcode);
			out.print(piccode);
		}else{
			out.print("验证码输入错误");
		}
		out.flush();
		
		out.close();
	}

}

近期会更新其他的验证码验证方式

在servlet中实现验证码的功能

1:使用的工具

2:目录结构

3:源码

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