菜鸟学Java（六）——简单验证码生成(Java版)

时间：2024-01-18 15:51:23

验证码大家都知道，它的作用也不用我多说了吧。如果不太清楚请参见百度百科中的解释，一般验证码的生成就是随机产生字符（数字、字母或者汉字等），然后将这些生成的字符绘制成一张图片，再在图片上加上一些干扰元素，如各种线条之类的。好了废话不多说一起往下看：

菜鸟学Java（六）——简单验证码生成(Java版)

简单的登录页面（代码并不完整，只有验证码部分） 
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <title>验证码</title>

    <script type="text/javascript">

 //刷新验证码的js函数

function changeCode() {

var imgNode = document.getElementById("vimg");                  

//重新加载验证码，达到刷新的目的

imgNode.src = "servlet/AuthImageServlet?t=" + Math.random();  // 防止浏览器缓存的问题

}

    </script>

  </head>

  <body>

    <form action="checkServlet" method="post">

        <label>输入验证码</label><br/>

        <input type="text" name="randomCode"/><img id="vimg"  title="点击更换" onclick="changeCode();" src="servlet/AuthImageServlet"><br/>

        <input type="submit" value="submit">

    </form>

  </body>

</html>

通过session.getAttribute("rand")，获得生成的验证码，然后跟用户输入的进行比较，再根据比较结果做相应的处理。

通过servlet生成验证码：

package com.util.servlet;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.IOException;

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;

import javax.servlet.http.HttpSession;

public class AuthImageServlet extends HttpServlet {

    private static final String CONTENT_TYPE = "text/html; charset=gb2312";

    //设置字母的大小,大小

    private Font mFont = new Font("Times New Roman", Font.PLAIN, 17);

    public void init() throws ServletException

    {

        super.init();

    }

    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 service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException

    {

        response.setHeader("Pragma","No-cache");

        response.setHeader("Cache-Control","no-cache");

        response.setDateHeader("Expires", 0);

        //表明生成的响应是图片

        response.setContentType("image/jpeg");   

        int width=100, height=18;

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);   

        Graphics g = image.getGraphics();

        Random random = new Random();

        g.setColor(getRandColor(200,250));

        g.fillRect(1, 1, width-1, height-1);

        g.setColor(new Color(102,102,102));

        g.drawRect(0, 0, width-1, height-1);

        g.setFont(mFont);   

        g.setColor(getRandColor(160,200));   

        //画随机线

        for (int i=0;i<155;i++)

        {

            int x = random.nextInt(width - 1);

            int y = random.nextInt(height - 1);

            int xl = random.nextInt(6) + 1;

            int yl = random.nextInt(12) + 1;

            g.drawLine(x,y,x + xl,y + yl);

        }   

        //从另一方向画随机线

        for (int i = 0;i < 70;i++)

        {

            int x = random.nextInt(width - 1);

            int y = random.nextInt(height - 1);

            int xl = random.nextInt(12) + 1;

            int yl = random.nextInt(6) + 1;

            g.drawLine(x,y,x - xl,y - yl);

        }   

        //生成随机数,并将随机数字转换为字母

        String sRand="";

        for (int i=0;i<6;i++)

        {

            int itmp = random.nextInt(26) + 65;

            char ctmp = (char)itmp;

            sRand += String.valueOf(ctmp);

            g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));

            g.drawString(String.valueOf(ctmp),15*i+10,16);

        }   

        HttpSession session = request.getSession(true);

        session.setAttribute("rand",sRand);

        g.dispose();

        ImageIO.write(image, "JPEG", response.getOutputStream());

    }   

}

web.xml中的servlet配置信息：

<?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>

    <servlet-name>AuthImageServlet</servlet-name>

    <servlet-class>com.util.servlet.AuthImageServlet</servlet-class>

  </servlet>

  <servlet-mapping>

    <servlet-name>AuthImageServlet</servlet-name>

    <url-pattern>/servlet/AuthImageServlet</url-pattern>

  </servlet-mapping>

  <welcome-file-list>

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

  </welcome-file-list>

</web-app>

就这样验证码的功能就实现了，很简单、很实用。当然还有更加美观，更加严密的方式，有兴趣的朋友可以深入研究。这里就跟大家分享一个比较简单的方式。欢迎各位批评指正。

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