J2EE动态生成验证码可刷新

hzfree001 2010-12-08 03:59:10

1、使用servlet生成验证码



package com.free.util;



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.ServletOutputStream;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;



public class CodeMakerServlet extends HttpServlet

{

      /**

	 * 

	 */

	private static final long serialVersionUID = 1L;

	

	//生成随机类

    Random random = new Random();

    

	//验证码字体

    private Font[] codeFont =

    {

        new Font("Times New Roman", Font.PLAIN,18), 

        new Font("Times New Roman", Font.PLAIN, 18),

        new Font("Times New Roman", Font.PLAIN,18),

        new Font("Times New Roman", Font.PLAIN, 18)

    };

    //验证码数字颜色

    private Color[] color =

    {

       Color.BLACK, Color.RED, Color.DARK_GRAY, Color.BLUE

    };



    String codeNumbers = "";



    int width = 60, height = 20;



    // 处理 HTTP get 请求

    public void doGet(HttpServletRequest request, HttpServletResponse response)

                      throws ServletException, IOException

    {

    	System.out.println("生成验证码");

        // 清空缓冲区

        response.reset();



        // 注意这里的MIME类型

        response.setContentType("image/png");



        // 设置页面不缓存

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

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

        response.setDateHeader("Expires", 0);



        // 创建一个图像,验证码显示的图片大小

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



        // 获取图形上下文

        Graphics g = image.getGraphics();

        

        // 设置背景

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

        g.fillRect(0, 0, width, height);



        for (int i = 0; i < 4; i++)

        {

            drawCode(g, i);

        }

        //添加干扰线

        drawNoise(g, 12);



        // 绘制边框

        //g.setColor(Color.gray);

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



        // 将验证码内容保存进session中，用于验证用户输入是否正确时使用

        HttpSession session = request.getSession(true);

        session.removeAttribute("rand");

        session.setAttribute("rand", codeNumbers);

        // 重设字符串

        codeNumbers = "";

        // 利用ImageIO类的write方法对图像进行编码

        ServletOutputStream sos = response.getOutputStream();

        ImageIO.write(image, "PNG", sos);

        sos.close();

    }



    // 绘制验证码

    public void drawCode(Graphics graphics, int i)

    {

        String number = String.valueOf(random.nextInt(10));

        graphics.setFont(codeFont[i]);

        graphics.setColor(color[i]);

        //绘制验证码到图片X、Y

        graphics.drawString(number, 6 + i * 13,16);



        codeNumbers += number;

    }



    // 绘制干扰线

    public void drawNoise(Graphics graphics, int lineNumber)

    {

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

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

        {

            int pointX1 = 1 + (int)(Math.random() * width);

            int pointY1 = 1 + (int)(Math.random() * height);

            int pointX2 = 1 + (int)(Math.random() * width);

            int pointY2 = 1 + (int)(Math.random() * height);

            graphics.drawLine(pointX1, pointY1, pointX2, pointY2);

        }

    }

    public Color getRandColor(int fc,int bc){//给定范围获得随机颜色

    	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);

	}

    // 处理 HTTP post 请求, 和doGet一样

    public void doPost(HttpServletRequest request, HttpServletResponse response)

        throws ServletException, IOException

    {

        doGet(request, response);

    }

}

调用页面



<%@ 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>servlet生成验证码</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 refreshcode(){

			document.getElementById("code").src="servlet/CodeMakerServlet?a="+Math.random()+100;

			return false;

		}

	</script>

  </head>

  

  <body>

  	(servlet页面生成验证码)<br/><br/>

  	<form method=post action="check.jsp">

  	用户名：<input type="text" name="userName" size="15" value=""><br>

	密码：<input type="text" name="password" size="15" value=""><br>

  	验证码：<input type="text" size="4" maxlength="4" name="rand"/>

    <img id="code" src="servlet/CodeMakerServlet" title="看不清点击刷新验证码" style="cursor : pointer;"  onclick="return refreshcode()"/>

  	<input type=submit value="提交">

  	</form>

  </body>

</html>