JSP验证码生成点击按钮更新

piperzero

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点击“看不清换一张”

测试用例：

Index.jsp

<%@ page contentType="text/html; charset=utf-8" language="java"
	import="java.util.*" errorPage=""%>
<HTML>
	<head>
		<title>测试</title>
	</head>

	<BODY id="body">
		<form>
				<img border=0 src="ImageMaskServlet" width="40" height="16" id = "imageMask">
				<a href = "#" style = "font-size: 13px;margin-left: 5px;" onclick = "myReload()">看不清换一张</a>
		</form>
	    <script type="text/javascript">
	    //用于刷新验证码
		 function myReload(){  
            document.getElementById("imageMask").src=document.getElementById("imageMask").src+"?nocache="+new Date().getTime();  
        }  
		</script>
	</BODY>
</HTML>

ImageMaskServlet

package javaServlet;

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;

public class ImageMaskServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		int width = 60, height = 20;
		//创建图象 
		BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
		//获取图形上下文 
		Graphics graphics = image.getGraphics();
		//生成随机类
		Random random = new Random();
		//设定背景色 
		graphics.setColor(getRandColor(200, 250));
		//验证码大小
		graphics.fillRect(0, 0, width, height);
		//设置字体
		graphics.setFont(new Font("Times New Roman", Font.PLAIN, 18));
	    //graphics.setColor(getRandColor(160, 200));
		//随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
		for (int i = 0; i < 155; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			graphics.drawLine(x, y, x + xl, y + yl);
		}
		//取随机产生的认证码(4位数字) 
		String sRand = "";
		for (int i = 0; i < 4; i++) {
			//0~9
			String rand = String.valueOf(random.nextInt(10));
			sRand += rand;
			//设置数字颜色
			graphics.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
			//把随机产生的4位数画在图片上
			graphics.drawString(rand, 13 * i + 6, 16);
		}
		//放在session中
		request.getSession().setAttribute("imageMask", sRand);
		//图象生效 
		graphics.dispose();
		//输出图象到页面 
		ImageIO.write(image, "JPEG", response.getOutputStream());
	}
	//生成随机颜色
	public Color getRandColor(int fc, int bc) {
		Random random = new Random();
		if (fc > 255){
			fc = 255;
		}
		if (bc > 255){
			bc = 255;
		}
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}
}

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