图片验证码

<div class="login-box clearfix" style="z-index:60;">
    <label>图形验证码</label>
    <div class="yzm-box">
        <input id="captcha" name="captcha" type="text" class="yzm" maxlength="10"
               placeholder="点击右侧图片可刷新" onblur="checkCaptcha();"/>
        <a style='cursor:pointer;'><img
                src="${pageContext.request.contextPath}/jcaptcha/captcha?d=" +new
                Date().getTime()
                onclick="this.src='${pageContext.request.contextPath}/jcaptcha/captcha?d='+new Date().getTime()"/></a>
    </div>
    <span id="captchaOk" class="ok" style="display:none;"></span>
    <div id="captchaErr" class="form-hint" style="display:none;"></div>

package com.bjpowernode.p2p.web;

import constant.Constants;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;

@Controller
public class JCaptchaController {

    private static final Logger logger =
            LogManager.getLogger(JCaptchaController.class);

    /**
     * 图片宽度：120px
     */
    public static final int WIDTH = 120;
    /**
     * 图片高度：50px
     */
    public static final int HEIGHT = 50;

    /**
     * 处理图片验证码方法
     *
     * @param request
     * @param response
     */
    @RequestMapping(value = "/jcaptcha/captcha")
    public void handleCaptchaRequest(HttpServletRequest request,
                                     HttpServletResponse response) {
        //生成6位随机验证码
        String captcha = this.getRandomCode(2);
        try {
            //创建字节数组输出流
            ByteArrayOutputStream jpegOutputStream = new
                    ByteArrayOutputStream();
            //创建图片缓存对象,BufferedImage.TYPE_INT_RGB ： 表示一个图像，该图像具有整数像素的 8 位 RGB 颜色
            BufferedImage bufferedImage = new BufferedImage(WIDTH, HEIGHT,
                    BufferedImage.TYPE_INT_RGB);
            //获取图片的画布
            Graphics graphics = bufferedImage.getGraphics();
            //设置画布背景色
            graphics.setColor(Color.WHITE);
            //设置画布填充区域
            graphics.fillRect(0, 0, WIDTH, HEIGHT);
            //边框区域
            graphics.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
            //设置字体颜色
            graphics.setColor(Color.BLUE);
            //设置字体样式
            graphics.setFont(new Font("微软雅黑", Font.ITALIC, 32));
            //填充数据
            graphics.drawString(captcha, 10, 38);

            //将生成的验证码存放到session中
            request.getSession().setAttribute(Constants.CAPTCHA, captcha);

            ImageIO.write(bufferedImage, "jpeg", jpegOutputStream);
            byte[] captchaChallengeAsJpeg = jpegOutputStream.toByteArray();

            //将验证码输出到页面
            response.setHeader("Cache-Control", "no-store");
            response.setHeader("Pragma", "no-cache");
            response.setDateHeader("Expires", 0L);
            response.setContentType("image/jpeg");
            ServletOutputStream respOs = response.getOutputStream();
            respOs.write(captchaChallengeAsJpeg);
            respOs.flush();
            respOs.close();


        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    /**
     * 生成0-9，a-z,A-Z的随机字符串
     *
     * @param count
     * @return
     */
    private String getRandomCode(int count) {
        String[] array =
                {"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", "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"};
        StringBuilder result = new StringBuilder();
        for (int i = 0; i < count; i++) {
            //生成一个下标0-61之间一个整数
            int index = (int) Math.round(Math.random() * 61);
            //从array数组中获取该下标字符放到result中
            result.append(array[index]);
        }

        return result.toString();
    }
}