验证码的使用(Java和PHP版)

悠悠 2022-08-27 09:46 147阅读 0赞

验证码的作用大部分都是为减少服务器压力而设计的，这玩意也挺古老的，谈不上什么新奇。无论是java还是php生成验证码的原理都一样。

1.php验证码

<?php
    //checkNum.php
    session_start();
    function random($len)
    {
    $srcstr="ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    mt_srand();//配置乱数种子
    $strs="";
    for($i=0;$i <$len;$i++){
    $strs.=$srcstr[mt_rand(0,35)];
    }
    
    return strtoupper($strs);
    }
    $str=random(4); //随机生成的字符串" title="字符串" >字符串
    $width = 50; //验证码图片的宽度
    $height = 20; //验证码图片的高度
    
    @header("Content-Type:image/png");
    $_SESSION["code"] = $str;
    //echo $str;
    $im=imagecreate($width,$height);
    //背景色
    $back=imagecolorallocate($im,0xFF,0xFF,0xFF);
    //模糊点颜色
    $pix=imagecolorallocate($im,187,230,247);
    //字体色
    $font=imagecolorallocate($im,41,163,238);
    //绘模糊作用的点
    mt_srand();
    for($i=0;$i <1000;$i++)
    {
    imagesetpixel($im,mt_rand(0,$width),mt_rand(0,$height),$pix);
    }
    imagestring($im, 5, 7, 5,$str, $font);
    imagerectangle($im,0,0,$width-1,$height-1,$font);
    imagepng($im);
    imagedestroy($im);
    $_SESSION["code"] = $str;
    
    ?>

基本上都是先调用一个绘图的方法，把图像放到输出流，之后显示在页面上

![SouthEast][]

2.java版验证码

java这块就麻烦点，生成验证码的程序一般写在servlet里，这种是最简单的方式。稍复杂的可以用一些第三方的验证码jar包

（1）数字版验证码

package org.lxh;
    
    import java.io.IOException;
    
    import javax.servlet.ServletException;
    import javax.servlet.ServletOutputStream;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import java.awt.*;
    import java.awt.image.*;
    import java.util.*;
    
    import javax.imageio.*;
    
    import com.sun.image.codec.jpeg.JPEGCodec;
    import com.sun.image.codec.jpeg.JPEGImageEncoder;
    
    public class ImageCode2 extends HttpServlet {
    	private static final long serialVersionUID = 1L;
    
    	protected void doGet(HttpServletRequest request,
    			HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		this.doPost(request, response);
    	}
    
    	protected void doPost(HttpServletRequest request,
    			HttpServletResponse response) throws ServletException, IOException {
    		// 在内存中创建图象
    		int iWidth = 60, iHeight = 18;
    		BufferedImage image = new BufferedImage(iWidth, iHeight,
    				BufferedImage.TYPE_INT_RGB);
    		// 获取图形上下文
    		Graphics g = image.getGraphics();
    		// 设定背景色
    		g.setColor(Color.white);
    		g.fillRect(0, 0, iWidth, iHeight);
    		// 画边框
    		g.setColor(Color.black);
    		g.drawRect(0, 0, iWidth - 1, iHeight - 1);
    		// 取随机产生的认证码(4位数字)
    		Random random = new Random();
    		String rand = String.valueOf(random.nextInt(10000));
    		// rand=rand.substring(0,rand.indexOf("."));
    		switch (rand.length()) {
    		case 1:
    			rand = "000" + rand;
    			break;
    		case 2:
    			rand = "00" + rand;
    			break;
    		case 3:
    			rand = "0" + rand;
    			break;
    		default:
    			rand = rand;
    			break;
    		}
    		// 将认证码存入SESSION
    		request.getSession().setAttribute("Rand", rand);
    		// 将认证码显示到图象中
    		g.setColor(Color.black);
    		g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
    		g.drawString(rand, 10, 15);
    		// 随机产生88个干扰点,使图象中的认证码不易被其它程序探测到
    		// Random random = new Random();
    		for (int iIndex = 0; iIndex < 88; iIndex++) {
    			int x = random.nextInt(iWidth);
    			int y = random.nextInt(iHeight);
    			g.drawLine(x, y, x, y);
    		}
    		// 图象生效
    		g.dispose();
    
    		ServletOutputStream outstream = response.getOutputStream();
    		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(outstream);
    
    		encoder.encode(image);
    		outstream.flush();
    	}
    
    }

之后在页面上请求这个servlet，验证码就出来了，页面代码如下所示：

<%@ 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>验证码的使用</title>
    
    </head>
    <script language="javascript" type="text/javascript">
      function changeImage(img){
       
       img.src="ImageCode?t="+new Date().getTime();
      }
     </script>
    <body>
        输入验证码：<input type="text"/><img src="ImageCode" id="img" οnclick="changeImage(this)" style="cursor: pointer;"/>
    </body>
    </html>

页面效果如下：

![SouthEast 1][]

（2）稍微复杂一点的验证码

package org.lxh;
    
    import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics2D;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    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 com.sun.image.codec.jpeg.JPEGCodec;
    import com.sun.image.codec.jpeg.JPEGImageEncoder;
    
    public class ImageCode extends HttpServlet {
    	// 定义可选择的字符
    	public static final char[] CHARS = { '2', '3', '4', '5', '6', '7', '8',
    			'9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M',
    			'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
    	static Random random = new Random();
    
    	public String getRandomString() {
    		StringBuffer buffer = new StringBuffer();
    		for (int i = 0; i < 6; i++) { // 生成六个字符
    			buffer.append(CHARS[random.nextInt(CHARS.length)]);
    		}
    		return buffer.toString();
    	}
    
    	public static Color getRandomColor() { // 得到随机颜色
    		return new Color(random.nextInt(255), random.nextInt(255),
    				random.nextInt(255));
    	}
    
    	public static Color getReverseColor(Color c) { // 得到颜色的反色
    		return new Color(255 - c.getRed(), 255 - c.getGreen(),
    				255 - c.getBlue());
    	}
    
    	public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		response.setContentType("image/jpeg"); // 设置输出类型
    		String randomString = getRandomString();
    		System.out.println(randomString);
    		// 将getSession（）设置为true，当会话不存在是返回null
    		request.getSession(true).setAttribute("ImageCode", randomString);
    
    		// 设置图片的宽、高
    		int width = 100;
    		int height = 30;
    
    		Color bcolor = getRandomColor(); // 前景色
    		Color fcolor = getReverseColor(getRandomColor()); // 设置背景色
    
    		// 创建一个彩色图片
    		BufferedImage bimage = new BufferedImage(width, height,
    				BufferedImage.TYPE_INT_BGR);
    		// 创建绘图对象
    		Graphics2D g = bimage.createGraphics();
    		// 字体样式为宋体,加粗，20磅
    		g.setFont(new Font("宋体", Font.BOLD, 20));
    		// 先画出背景色
    		g.setColor(bcolor);
    		g.fillRect(0, 0, width, height);
    		// 再画出前景色
    		g.setColor(fcolor);
    		// 绘制随机字符
    		g.drawString(randomString, 20, 22);
    		// 画出干扰点
    		for (int i = 0, n = random.nextInt(100); i < n; i++) {
    			g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
    		}
    
    		ServletOutputStream outstream = response.getOutputStream();
    		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(outstream);
    
    		encoder.encode(bimage);
    		outstream.flush();
    
    	}
    	public void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    	}
    }

这种方式的验证码是下面这个样子：

![SouthEast 2][]

后面的工作就简单了，如果要看验证码对不对，直接从session里取出和输入框里的比对一下就OK了。

[SouthEast]: /images/20220824/fc9f04ecb10d46408c3784a43ade8979.png
[SouthEast 1]: /images/20220824/7e17c9cb6b89452997d6134ac705a618.png
[SouthEast 2]: /images/20220824/6d14630a253a48d3bfc347b5f1fd35e2.png