WEB项目-登录验证码

Servlet代码

package com.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.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/checkcode")
public class CheckcodeServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		/**
		 * 1、获取画布对象 2、获取画笔对象 2.1画一个实心的矩形，大小和画布相同 2.2画一个有边框的空心矩形 3、提前准备好数据
		 * ABCDEFGHIJKLMNabcdefghijklmnzxc1234567890 3.1随机获取4个数据
		 * 3.2把随机获取的数据画到画布上 4、画干扰线 5、把内存中的验证码输出到客户端
		 */
		int width = 120;
		int height = 30;
		// 获取画布对象
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		// 获取画笔对象
		Graphics g = image.getGraphics();
		//画一个实心矩形
		g.setColor(Color.GRAY);
		//设置画笔的颜色
		g.fillRect(0,0, width, height);
		//画一个边框
		g.setColor(Color.BLACK);
		g.drawRect(0, 0, width-1, height-1);
		//准备数据
		String words = "ABCDEFGHIJKLMNabcdefghijklmnzxc1234567890";
		//随机获取4个字符
		Random random = new Random();
		g.setColor(Color.RED);
		g.setFont(new Font("隶书",Font.BOLD,20));
		//验证码第一个字符的坐标
		int x = 20;
		int y = 20;
		//获取words中随机一个字符的下标
		for(int i = 0;i<4;i++){
			int index = random.nextInt(words.length());
			char ch = words.charAt(index);
			//画到画布上去
			g.drawString(ch+"", x, y);
			x+=20;
		}
		//画干扰线
		g.setColor(Color.BLACK);
		int x1,x2,y1,y2;
		for(int i = 0;i<4;i++){
			x1 = random.nextInt(width);
			y1 = random.nextInt(height);
			x2 = random.nextInt(width);
			y2 = random.nextInt(height);
			g.drawLine(x1, y1, x2, y2);
		}
		
		
		// 把图片输出到客户端
		ImageIO.write(image, "jpg", response.getOutputStream());
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

登录HTML页面代码

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h3>登录</h3>
	<form action="" method="post">
		用户名:<input type="text" name="username"/><br/>
		密码:&nbsp;&nbsp;&nbsp;&nbsp;<input type="password" name="password"/><br/>
		验证码：<img  id="imgId"alt="验证码" src="/Checkcode/checkcode" onclick="changeCode()"><br/>
		<input type="submit" value="登录"/>
		
	</form>
</body>
	<script type="text/javascript">
	//时间戳
		function changeCode(){
			var img = document.getElementById("imgId");
			img.src = "/Checkcode/checkcode?time="+new Date().getTime();
		}
		
		
	</script>
</html>

WEB项目-登录验证码

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