模拟登陆验证码操作 

package com.project.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 验证码
 * Servlet implementation class CheckCodeServlet
 */
@WebServlet("/checkCode")
public class CheckCodeServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CheckCodeServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置响应信息的MIME类型为jpeg图片
        response.setContentType("image/jpeg");
        //创建130*53的内存图片
        BufferedImage img = new BufferedImage(130,53,BufferedImage.TYPE_INT_RGB);
        //得到画笔
        Graphics g = img.getGraphics();
        //随机产生背景颜色 
        g.setColor(new Color((int)(Math.random()*50+175),(int)(Math.random()*50+175),(int)(Math.random()*50+175)));
        //绘制实心矩形
        g.fillRect(0, 0, 130, 53);
        //设置字体格式
        g.setFont(new Font("宋体",Font.BOLD,30));
        //设置字体颜色
        g.setColor(new Color((int)(Math.random()*70+50),(int)(Math.random()*70+50),(int)(Math.random()*70+50)));
        
        for (int i=0; i<4; i++){
            //随机产生大写字母(A-Z)
            char c = (char) (Math.random()*26+65);
            //向图片写入文字，x每次增加12pix,y每次随机变化（22-52）pix
            g.drawString(c+"",24*i+12,(int)(Math.random()*30+22));
            //g.drawString(c+"",(int)(Math.random()*117+22),(int)(Math.random()*30+22));
        }
        
        //将img随机产生的图片，以二进制方式输出到客户端
        ImageIO.write(img, "jpeg", response.getOutputStream());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
    }

}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>登录界面</title>
<script type="text/javascript" src="/testweb/jquery-1.12.1.js"></script>
<script type="text/javascript">
     function imgChange(){
        //"/testweb/checkCode?a="+Math.random()清除浏览器缓存
        //随机从服务器产生随机数，不会从缓存中去取
        //浏览器存在缓存，当客户端浏览器向服务器发送请求时，会将下载的内容在浏览器缓存起来
        //如果客户端再次请求服务器的同一个页面，会先看浏览器缓存中是否有下载的资源，
        //如果有，会从浏览器缓存中获取资源如果没有，再从服务器下载
        $("#codeImg").attr("src","/testweb/checkCode?a="+Math.random());
    } 
    $(function(){
        $("#clc").click(function(){
            $("#codeImg").attr("src","/testweb/checkCode?a="+Math.random());
        })
    });
    
</script>
</head>
<body>
    <form action="login" method="post">
        用户名：<input type="text" name="userName"><br/>
        密码：<input type="password" name="pwd"><br/>
        <img alt="" src="/testweb/checkCode" id="codeImg">
        <input type="button" id="clc" value="点击切换验证码"><br/>
        <a href="javascript:imgChange()">看不清楚，换一张</a><br/>
        验证码：<input type="text" name="check">
    </form>
</body>
</html>

 

posted @ 2017-10-24 23:07  沉迷学习，日渐消瘦  阅读(177)  评论(0)    收藏  举报