java生成随机验证码

产生图片servlet 

import java.awt.Color; 

import java.awt.Font; 

import java.awt.Graphics2D; 

import java.awt.image.BufferedImage; 

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; 

/** 

* Package name : com.skcc.sample.action 

* File name : VerifyCodeServlet.java 

* Author : Administrator 

* Date : 2008-9-4 

* Description : VerifyCodeServlet 

*/ 

public class VerifyCodeServlet extends HttpServlet { 

/** 

* 验证码图片的宽度。 

*/ 

private int width = 60; 

/** 

* 验证码图片的高度。 

*/ 

private int height = 20; 

/** 

* 验证码字符个数 

*/ 

private int codeCount = 4; 

/** 

* xx 

*/ 

private int xx = 0; 

/** 

* 字体高度 

*/ 

private int fontHeight; 

/** 

* codeY 

*/ 

private int codeY; 

/** 

* codeSequence 

*/ 

char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 

'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 

'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; 

/** 

* 初始化验证图片属性 

*/ 

public void init() throws ServletException { 

// 从web.xml中获取初始信息 

// 宽度 

String strWidth = this.getInitParameter("width"); 

// 高度 

String strHeight = this.getInitParameter("height"); 

// 字符个数 

String strCodeCount = this.getInitParameter("codeCount"); 

// 将配置的信息转换成数值 

try { 

if (strWidth != null && strWidth.length() != 0) { 

width = Integer.parseInt(strWidth); 

} 

if (strHeight != null && strHeight.length() != 0) { 

height = Integer.parseInt(strHeight); 

} 

if (strCodeCount != null && strCodeCount.length() != 0) { 

codeCount = Integer.parseInt(strCodeCount); 

} 

} catch (NumberFormatException e) { 

e.printStackTrace(); 

} 

xx = width / (codeCount + 1); 

fontHeight = height - 2; 

codeY = height - 4; 

} 

/** 

* @param req 

* @param resp 

* @throws ServletException 

* @throws java.io.IOException 

*/ 

protected void service(HttpServletRequest req, HttpServletResponse resp) 

throws ServletException, java.io.IOException { 

// 定义图像buffer 

BufferedImage buffImg = new BufferedImage(width, height, 

BufferedImage.TYPE_INT_RGB); 

Graphics2D gd = buffImg.createGraphics(); 

// 创建一个随机数生成器类 

Random random = new Random(); 

// 将图像填充为白色 

gd.setColor(Color.WHITE); 

gd.fillRect(0, 0, width, height); 

// 创建字体，字体的大小应该根据图片的高度来定。 

Font font = new Font("Fixedsys", Font.PLAIN, fontHeight); 

// 设置字体。 

gd.setFont(font); 

// 画边框。 

gd.setColor(Color.BLACK); 

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

// 随机产生160条干扰线，使图象中的认证码不易被其它程序探测到。 

gd.setColor(Color.BLACK); 

for (int i = 0; i < 160; i++) { 

int x = random.nextInt(width); 

int y = random.nextInt(height); 

int xl = random.nextInt(12); 

int yl = random.nextInt(12); 

gd.drawLine(x, y, x + xl, y + yl); 

} 

// randomCode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 = new StringBuffer(); 

int red = 0, green = 0, blue = 0; 

// 随机产生codeCount数字的验证码。 

for (int i = 0; i < codeCount; i++) { 

// 得到随机产生的验证码数字。 

String strRand = String.valueOf(codeSequence[random.nextInt(36)]); 

// 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。 

red = random.nextInt(255); 

green = random.nextInt(255); 

blue = random.nextInt(255); 

// 用随机产生的颜色将验证码绘制到图像中。 

gd.setColor(new Color(red, green, blue)); 

gd.drawString(strRand, (i + 1) * xx, codeY); 

// 将产生的四个随机数组合在一起。 

randomCode.append(strRand); 

} 

// 将四位数字的验证码保存到Session中。 

HttpSession session = req.getSession(); 

session.setAttribute("validateCode", randomCode.toString()); 

// 禁止图像缓存。 

resp.setHeader("Pragma", "no-cache"); 

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

resp.setDateHeader("Expires", 0); 

resp.setContentType("image/jpeg"); 

// 将图像输出到Servlet输出流中。 

ServletOutputStream sos = resp.getOutputStream(); 

ImageIO.write(buffImg, "jpeg", sos); 

sos.close(); 

} 

} 

产生结果servlet 

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; 

/** 

* Package name : com.skcc.sample.action 

* File name : ResultServlet.java 

* Author : Administrator 

* Date : 2008-9-4 

* Description : ResultServlet 

*/ 

public class ResultServlet extends HttpServlet { 

/** 

* The doGet method of the servlet. <br> 

* 

* This method is called when a form has its tag value method equals to get. 

* 

* @param request the request send by the client to the server 

* @param response the response send by the server to the client 

* @throws ServletException if an error occurred 

* @throws IOException if an error occurred 

*/ 

public void doGet(HttpServletRequest request, HttpServletResponse response) 

throws ServletException, IOException { 

doPost(request, response); 

} 

/** 

* The doPost method of the servlet. <br> 

* 

* This method is called when a form has its tag value method equals to post. 

* 

* @param request the request send by the client to the server 

* @param response the response send by the server to the client 

* @throws ServletException if an error occurred 

* @throws IOException if an error occurred 

*/ 

public void doPost(HttpServletRequest request, HttpServletResponse response) 

throws ServletException, IOException { 

response.setContentType("text/html;charset=utf-8"); 

String validateC = (String) request.getSession().getAttribute("validateCode"); 

String veryCode = request.getParameter("veryCode"); 

PrintWriter out = response.getWriter(); 

if(veryCode==null||"".equals(veryCode)){ 

out.println("验证码为空"); 

}else{ 

if(validateC.equals(veryCode)){ 

out.println("验证码正确"); 

}else{ 

out.println("验证码错误"); 

} 

} 

out.flush(); 

out.close(); 

} 

} 

js文件 

function changeImg(){ 

var imgSrc = $("#imgObj"); 

var src = imgSrc.attr("src"); 

imgSrc.attr("src",chgUrl(src)); 

} 

//时间戳 

//为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳 

function chgUrl(url){ 

var timestamp = (new Date()).valueOf(); 

url = url.substring(0,17); 

if((url.indexOf("&")>=0)){ 

url = url + "×tamp=" + timestamp; 

}else{ 

url = url + "?timestamp=" + timestamp; 

} 

return url; 

} 

function isRightCode(){ 

var code = $("#veryCode").attr("value"); 

code = "c=" + code; 

$.ajax({ 

type:"POST", 

url:"resultServlet", 

data:code, 

success:callback 

}); 

} 

function callback(data){ 

$("#info").html(data); 

} 

页面verifyCode.jsp 

<%@ 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"> 

<script type="text/javascript" src="js/verifyCode.js"></script> 

<script type="text/javascript" src="js/jquery.js"></script> 

<title>test verify code</title> 

</head> 

<body> 

<input id="veryCode" name="veryCode" type="text"/> 

<img id="imgObj" alt="" src="verifyCodeServlet"/> 

<a href="#" onclick="changeImg()">换一张</a> 

<input type="button" value="验证" onclick="isRightCode()"/> 

<div id="info"></div> 

</body> 

</html> 

最后记得配好web.xml 

<servlet> 

< servlet-name>VerifyCodeServlet</servlet-name> 

< servlet-class>com.sample.action.VerifyCodeServlet</servlet-class> 

</servlet> 

<servlet> 

< servlet-name>ResultServlet</servlet-name> 

< servlet-class>com.sample.action.ResultServlet</servlet-class> 

</servlet> 

< servlet-mapping> 

< servlet-name>VerifyCodeServlet</servlet-name> 

< url-pattern>/verifyCodeServlet</url-pattern> 

< /servlet-mapping> 

<servlet-mapping> 

< servlet-name>ResultServlet</servlet-name> 

< url-pattern>/resultServlet</url-pattern> 

< /servlet-mapping> 

转自：http://blog.csdn.net/cuilupeng999/archive/2008/09/04/2880514.aspx

package servlet; 

import java.awt.Color; 
import java.awt.Font; 
import java.awt.Graphics2D; 
import java.awt.image.BufferedImage; 
import java.io.IOException; 
import java.io.PrintWriter; 
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; 
/** 
* 生成随机验证码 
* @author cuiran 
* @date 2009-1-20 
* 
*/ 

@SuppressWarnings("serial") 
public class ValidateCodeServlet extends HttpServlet { 


//验证图片的宽度 
private int width=60; 
//验证图片的高度 
private int height=20; 
//验证码字符个数 
private int codeCount=4; 
private int x=0; 
//字体高度 
private int fontHeight; 
private int codeY; 
char[] codeSequence={'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 
'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; 
public ValidateCodeServlet() { 
super(); 
} 


public void destroy() { 
super.destroy(); 
} 


public void doGet(HttpServletRequest request, HttpServletResponse response) 
throws ServletException, IOException { 
this.doPost(request, response); 
} 


public void doPost(HttpServletRequest request, HttpServletResponse response) 
throws ServletException, IOException { 
//定义图像buffer 
BufferedImage buffImg=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); 
Graphics2D g=buffImg.createGraphics(); 
//创建一个随机数生成器类 
Random random=new Random(); 
//将图像填充为白色 
g.setColor(Color.WHITE); 
g.fillRect(0, 0, width, height); 
//创建字体，字体的大小应该根据图片的高度来定 
Font font=new Font("Fixedsys",Font.PLAIN,fontHeight); 

//设置字体 
g.setFont(font); 

//画边框 
g.setColor(Color.BLACK); 
g.drawRect(0, 0, width-1, height-1); 
//随机产生160条干扰线，使图像中的认证码不易被其他程序探测到 
g.setColor(Color.BLACK); 
for(int i=0;i<160;i++){ 
int x=random.nextInt(width); 
int y=random.nextInt(height); 
int x1=random.nextInt(12); 
int y1=random.nextInt(12); 
g.drawLine(x, y, x+x1, y+y1); 

} 
//randomCode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=new StringBuffer(); 
int red=0,green=0,blue=0; 

//随机产生codeCount数字的验证码 
for(int i=0;i<codeCount;i++){ 
//得到随机产生的验证码数字 
String strRand=String.valueOf(codeSequence[random.nextInt(36)]); 
//产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同 
red=random.nextInt(255); 
green=random.nextInt(255); 
blue=random.nextInt(255); 

//用随机产生的颜色将验证码绘制到图像中 
g.setColor(new Color(red,green,blue)); 
g.drawString(strRand, (i+1)*x, codeY); 
//将产生的四个随机数组合在一起。 
randomCode.append(strRand); 

} 

//将四位数字的验证码保存到session中 
HttpSession session=request.getSession(); 
session.setAttribute("validataCode", randomCode.toString()); 


//禁止图像缓存 
response.setHeader("Paragma", "no-cache"); 
response.setHeader("Cache-Control", "no-cache"); 
response.setDateHeader("Expires", 0); 

response.setContentType("image/jpeg"); 
//将图像输出到servlet输出流中 
ServletOutputStream sos=response.getOutputStream(); 
ImageIO.write(buffImg, "jpeg", sos); 
sos.close(); 
request.getRequestDispatcher("/index.jsp").include(request, response); 
} 
/** 
* 初始化验证图片属性 
*/ 
public void init() throws ServletException { 
//从web.xml中获取初始信息 
//宽度 
String strWidth=this.getInitParameter("width"); 
//高度 
String strHeight=this.getInitParameter("height"); 
//字符个数 
String strCodeCount=this.getInitParameter("codeCount"); 
//将配置信息转换成数值 
try{ 
if(strWidth!=null&&strWidth.length()!=0){ 
width=Integer.parseInt(strWidth); 
} 
if(strHeight!=null&&strHeight.length()!=0){ 
height=Integer.parseInt(strHeight); 
} 
if(strCodeCount!=null&strCodeCount.length()!=0){ 
codeCount=Integer.parseInt(strCodeCount); 
} 
}catch(NumberFormatException e){ 

} 
x=width/(codeCount+1); 
fontHeight=height-2; 
codeY=height-4; 
} 

} 

 

 

java里的验证码

 最近在一个J2EE系统里，要用到验证码，找到如下比较好的方法，是写成servlet的

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;
import javax.imageio.*;

/**
 * @author  yeeku.H.lee [e-mail]
 * @version  1.0
 * <br>Copyright (C), 2005-2008, yeeku.H.Lee
 * <br>This program is protected by copyright laws.
 * <br>Program Name:
 * <br>Date: 
 */
public class AuthImg extends HttpServlet
{
    private Font mFont = new Font("Arial Black", Font.PLAIN, 16);
    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);
        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));
        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);
        }
        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);
        }

        String sRand="";
        for (int i=0;i<6;i++)
        {
   String tmp = getRandomChar();
            sRand += tmp;
            g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
         g.drawString(tmp,15*i+10,15);
        }

        HttpSession session = request.getSession(true);
        session.setAttribute("rand",sRand);
        g.dispose();
        ImageIO.write(image, "JPEG", response.getOutputStream());
    }
    private String getRandomChar()
    {
  int rand = (int)Math.round(Math.random() * 2);
  long itmp = 0;
  char ctmp = '\u0000';
  switch (rand)
  {
   case 1:
    itmp = Math.round(Math.random() * 25 + 65);
    ctmp = (char)itmp;
    return String.valueOf(ctmp);
   case 2:
    itmp = Math.round(Math.random() * 25 + 97);
    ctmp = (char)itmp;
    return String.valueOf(ctmp);
   default :
    itmp = Math.round(Math.random() * 9);
    return String.valueOf(itmp);
  }
    }
}
 其中这是加了干扰线的了，并且用session来保存验证码了，
在登陆的jsp页面中，应该这样设置
 验证码如图：<img src="authImg" id="authImg"/>看不清？<a href="#" onClick="refresh()">单击此处刷新</a>
然后refesh()函数如下写
<script>
   function refresh()
   {
    document.getElementById("authImg").src='authImg?now=' + new Date();
   }
  </script>
之所以在最后加now,是防止浏览器的缓存

最后再在web.xml里配置下servlet

 <servlet>
        <servlet-name>img</servlet-name>
        <servlet-class>org.yeeku.web.AuthImg</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>img</servlet-name>
     <url-pattern>/authImg</url-pattern>
    </servlet-mapping>

分类: JAVA