验证码实例

 1
 package com.lljr.servlet;

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.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
 * 验证码
 * @AUTHER LiuLonglong
 * @Motto Goals determine what you are going to be.
 * @URL http://www.cnblogs.com/mvilplss/
 */
public class VerificationServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;
    // 设置字母的大小,大小
    private Font mFont = new Font("宋体", Font.BOLD, 28);

    @Override
    protected void service(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // 创建画板缓冲区
        int width = 132;
        int height = 45;
        BufferedImage img = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        // 获取画板
        Graphics g = img.getGraphics();
        g.setColor(new Color(255, 255, 255));
        g.fillRect(0, 0, width, height);// 填充颜色
        g.setColor(new Color(102, 102, 102));
        g.drawRect(0, 0, width - 1, height - 1);// 画出边框
        // 画随机线
        Random random = new Random();
        for (int i = 0; i < 15; i++) {
            int x = random.nextInt(width - 1);
            int y = random.nextInt(height - 1);
            int xl = random.nextInt(12) + 1;
            int yl = random.nextInt(48) + 1;
            g.setColor(new Color(random.nextInt(255), random.nextInt(5), random
                    .nextInt(10)));
            g.drawLine(x, y, x + xl, y + yl);
        }
        // 画上字符串
        g.setColor(new Color(25, 11, 222));
        g.setFont(mFont);
        String[] chars = { "1", "2", "3", "4", "5", "6", "7", "8", "9", "0",
                "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l",
                "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "s",
                "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", "S", "Y", "Z" };
        String randomString = "";
        for (int i = 0; i < 6; i++) {
            int index = random.nextInt(62);
            int rc = random.nextInt(256);
            int gc = random.nextInt(256);
            int bc = random.nextInt(25);
            g.setColor(new Color(rc, gc, bc));
            g.drawString(chars[index], 21 * i + 5, 30);
            randomString += chars[index];
        }
        g.dispose();
        g.dispose();
        HttpSession session = request.getSession();
        session.setAttribute("system_verification_code", randomString);
        ImageIO.write(img, "JPEG", response.getOutputStream());
    }

}

页面请求验证码：

<img id="_verification" src="${basePath}/verificationServlet.servlet"></img>

<a href="javascript:void(0);" onclick="_verification_reload()">刷新</a>

刷新按钮js：

function _verification_reload(){
$("#_verification").attr("src","${basePath}/verificationServlet.servlet?a="+Math.random());
}

实现效果：

如果部分浏览器显示为一堆乱码时，请加上以下代码来设置浏览器接受的形式：

response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");