图片验证的问题..在线等.

only__happy 2009-10-06 04:15:21

为什么保存在session中的值与图片的值不一致..

我在页面中输出session的值 ..总比图片里面的值慢一拍！！

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palosky 2009-10-07

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你看我这个可以的！

这是servlet



package servlet;



import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.io.PrintWriter;

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;



public class ImageCode extends HttpServlet {



	/**

	 * 

	 */

	private static final long serialVersionUID = 1L;



	public void service(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {



		// 首先设置页面不缓存

		response.setHeader("Pragma", "No-cache");

		response.setHeader("Cache-Control", "no-cache");

		response.setDateHeader("Expires", 0);



		// 定义图片的高度和宽度

		int width = 200;

		int height = 40;



		// 创建一个图像对象

		BufferedImage image = new BufferedImage(width, height,

				BufferedImage.TYPE_INT_RGB);



		// 得到图像的环境对象

		Graphics g = image.createGraphics();



		Random random = new Random();

		

		// 用随机色填充图像背景

		g.setColor(getRandomColor(160, 250));

		g.fillRect(0, 0, width, height);

		for (int i = 0; i < 5; i++) {

			g.setColor(getRandomColor(50, 100));

			int x = random.nextInt(width);

			int y = random.nextInt(height);

			g.drawOval(x, y, 6, 6);

		}

		

		//设置字体

		String[] fonts = {"Times New Roman","Georgia","Sylfaen"};

		String font=fonts[random.nextInt(fonts.length)];

		//System.out.println(font);

		g.setFont(new Font(font, Font.LAYOUT_LEFT_TO_RIGHT, 33));

		

		//准备画随机数

		String sRand = "";// 随机字符串

		String chars = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

		char[] ch = chars.toCharArray();

		for (int i = 0; i < 6; i++) {

			// 生成6个数字或者字符

			String rand = String.valueOf(ch[random.nextInt(chars.length())]);

			sRand += rand;

			//System.out.println(sRand);



			int red=20 + random.nextInt(80);

			int green=20 + random.nextInt(100);

			int blue=20 + random.nextInt(90);

			

			// 设置字体的颜色

			g.setColor(new Color(red,green,blue));

			

			// 将随机数字画在图像上

			g.drawString(rand, 25*(i+1), 34);//在这里改变相邻字母的间距



			// 生成干扰线

			for (int k = 0; k < 12; k++) {

				int x = random.nextInt(width);

				int y = random.nextInt(height);

				int x1 = random.nextInt(9);

				int y1 = random.nextInt(9);

				g.drawLine(x, y, x + x1, y + y1);

			}

		}



		//将随机生成的字符串写入session

		HttpSession session=request.getSession();

		session.setAttribute("code", sRand);

		g.dispose();//使图像生效

		ImageIO.write(image, "JPEG", response.getOutputStream());//输出图像到页面

	}



	/**

	 * 产生一个随机颜色

	 * 

	 * @param fc

	 *            颜色分量最小值

	 * @param bc

	 *            颜色分量最大值

	 */

	public Color getRandomColor(int fc, int bc) {

		Random random = new Random();

		int t=random.nextInt(8);

		

		int[] r={247,243,201,225,220,205,247,236};

		int[] g={248,223,249,238,238,245,242,243};

		int[] b={216,206,218,225,204,209,185,189};



		return new Color(r[t], g[t], b[t]);

		//return new Color(r,g,b);

	}



}

这是主页index.jsp



<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>

<html>

	<head>

		<title>index.jsp</title>	

	</head>



	<body>

	<form name="form" action="result.jsp" method="post">

		验证码:

		<input type="text" name="code">

		<p>

			<img src="/Common/ImageCode" border="1px" 

				onclick="this.src='/Common/ImageCode?num='+Math.random();"

				title="看不清?单击图片重新获取" name="img"><p>

			<input type="submit" value="提交">

	</form><br>

	<%

		out.println("当前时间: "+new Date()); 

	%>

	</body>

</html>

这是提交后的页面result.jsp



<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>

<html>

  <head>

    <title>result.jsp</title>

  </head>

  

  <body>

  	<%

  		String code=(String)session.getAttribute("code");

  		String inputcode=request.getParameter("code");

  		inputcode=inputcode.toUpperCase();

  		out.println("验证码:"+code);

  		out.println("用户输入:"+inputcode); 

  	%>

  </body>

</html>

我写的是忽略大小写的验证码。