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session 注册简单验证码的实现

2015-10-12 15:52 393 查看

一：简单实现界面：

二：代码实现

index.jsp原码

<%@ 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">
-->

</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" />
<img alt="" src="<%=request.getContextPath() %>/ValidateColorServlet">
<input type="submit" value="submit"/>

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

CheckCodeservlet原码：

package com.hp.yanzhengma;

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 CheckCodeservlet extends HttpServlet {

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

}

ValidateColorServlet原码：

package com.hp.yanzhengma;

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();
}
}

web.xml配置原码：

<span style="font-size:18px;"><?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>1011sessionyanzhengma</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>

<servlet>
<servlet-name>ValidateColorServlet</servlet-name>
<servlet-class>com.hp.yanzhengma.ValidateColorServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>CheckCodeservlet</servlet-name>
<servlet-class>com.hp.yanzhengma.CheckCodeservlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>ValidateColorServlet</servlet-name>
<url-pattern>/ValidateColorServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>CheckCodeservlet</servlet-name>
<url-pattern>/checkCodeservlet</url-pattern>
</servlet-mapping>
</web-app></span>

三：体会

提示信息重定向于另一个jsp并打印出：

表单中链接servlet：

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