产生验证码图片

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("c");  
        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>

 

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/cuilupeng999/archive/2008/09/04/2880514.aspx