java登录验证码实现代码

VerifyCodeServlet.java类：

复制代码代码如下:

package com.spring.controller;
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;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
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;
    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' };
    /**
     * 初始化验证图片属性
     */
    public void initxuan() throws ServletException {
        // 从web.xml中获取初始信息
        // 宽度
        String strWidth ="80";
        // 高度
        String strHeight ="30";
        // 字符个数
        String strCodeCount = "4";
        // 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) {
        }
        x = width / (codeCount + 1);
        fontHeight = height - 2;
        codeY = height - 4;
    }
    @RequestMapping(value="xuan/verifyCode",method=RequestMethod.GET)
    public void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, java.io.IOException {
        initxuan();
        // 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，使图象中的认证码不易被其它程序探测到。
        g.setColor(Color.BLACK);
        for (int i = 0; i < 10; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.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。
            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 = 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();
    }
}

ResultServlet.java:

复制代码代码如下:

package com.spring.controller;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
public class ResultServlet {
     @RequestMapping(value="resultServlet/validateCode",method=RequestMethod.POST)
     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();
     }
}

jsp页面：

<%@ 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">

        <title>test verify code</title>

    </head>

    <body>

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

        <img id="imgObj"  alt="" src="xuan/verifyCode"/>

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

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

        <div id="info"></div>

    </body>

</html>

<script type="text/javascript">

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();

    urlurl = url.substring(0,17);

    if((url.indexOf("&")>=0)){

        urlurl = url + "×tamp=" + timestamp;

    }else{

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

    }

    return url;

}

function isRightCode(){

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

    code = "c=" + code;

    $.ajax({

        type:"POST",

        url:"resultServlet/validateCode",

        data:code,

        success:callback

    });

}

function callback(data){

    $("#info").html(data);

}

</script>