HTTP Servlet Response一次性验证码的实现（页码SR4）

╰+攻爆jí腚メ 2023-07-07 12:35 23阅读 0赞

前端

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>Insert title here</title>
    
    <script type="text/javascript">
    	window.onload = function(){
    		
    	}
    	
    	function changeImg(obj){
    		obj.src = "/WEB14/checkImg?time="+new Date().getTime();
    	}
    </script>
    
    </head>
    <body>
    	<form action="/WEB13/login" method="post">
    		用户名：<input type="text" name="username"><br/>
    		密码：<input type="password" name="password"><br/>
    		验证码：<input type="text" name="username"><img onclick="changeImg(this)" src="/WEB14/checkImg"><br/>
    		<input type="submit" value="登录"><br/>
    	</form>
    </body>
    </html>

验证码代码

package cn.aynortechnology.checkimg;
    
    import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics;
    import java.awt.Graphics2D;
    import java.awt.image.BufferedImage;
    import java.io.BufferedReader;
    import java.io.FileReader;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    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;
     
    /**
     * 验证码生成程序
     * 
     * 
     * 
     */
    public class CheckImgServlet extends HttpServlet {
     
    	// 集合中保存所有成语
    	private List<String> words = new ArrayList<String>();
     
    	@Override
    	public void init() throws ServletException {
    		// 初始化阶段，读取new_words.txt
    		// web工程中读取 文件，必须使用绝对磁盘路径
    		String path = getServletContext().getRealPath("/WEB-INF/new_words.txt");
    		try {
    			BufferedReader reader = new BufferedReader(new FileReader(path));
    			String line;
    			while ((line = reader.readLine()) != null) {
    				words.add(line);
    			}
    			reader.close();
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
     
    	public void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		// 禁止缓存
    		// response.setHeader("Cache-Control", "no-cache");
    		// response.setHeader("Pragma", "no-cache");
    		// response.setDateHeader("Expires", -1);
     
    		int width = 120;
    		int height = 30;
     
    		// 步骤一 绘制一张内存中图片
    		BufferedImage bufferedImage = new BufferedImage(width, height,
    				BufferedImage.TYPE_INT_RGB);
     
    		// 步骤二 图片绘制背景颜色 ---通过绘图对象
    		Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔
    		// 绘制任何图形之前 都必须指定一个颜色
    		graphics.setColor(getRandColor(200, 250));
    		graphics.fillRect(0, 0, width, height);
     
    		// 步骤三 绘制边框
    		graphics.setColor(Color.WHITE);
    		graphics.drawRect(0, 0, width - 1, height - 1);
     
    		// 步骤四 四个随机数字
    		Graphics2D graphics2d = (Graphics2D) graphics;
    		// 设置输出字体
    		graphics2d.setFont(new Font("宋体", Font.BOLD, 18));
     
    		Random random = new Random();// 生成随机数
    		int index = random.nextInt(words.size());
    		String word = words.get(index);// 获得成语
     
    		// 定义x坐标
    		int x = 10;
    		for (int i = 0; i < word.length(); i++) {
    			// 随机颜色
    			graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random
    					.nextInt(110), 20 + random.nextInt(110)));
    			// 旋转 -30 --- 30度
    			int jiaodu = random.nextInt(60) - 30;
    			// 换算弧度
    			double theta = jiaodu * Math.PI / 180;
     
    			// 获得字母数字
    			char c = word.charAt(i);
     
    			// 将c 输出到图片
    			graphics2d.rotate(theta, x, 20);
    			graphics2d.drawString(String.valueOf(c), x, 20);
    			graphics2d.rotate(-theta, x, 20);
    			x += 30;
    		}
     
    		// 将验证码内容保存session
    		request.getSession().setAttribute("checkcode_session", word);
     
    		// 步骤五 绘制干扰线
    		graphics.setColor(getRandColor(160, 200));
    		int x1;
    		int x2;
    		int y1;
    		int y2;
    		for (int i = 0; i < 30; i++) {
    			x1 = random.nextInt(width);
    			x2 = random.nextInt(12);
    			y1 = random.nextInt(height);
    			y2 = random.nextInt(12);
    			graphics.drawLine(x1, y1, x1 + x2, x2 + y2);
    		}
     
    		// 将上面图片输出到浏览器 ImageIO
    		graphics.dispose();// 释放资源
    		ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
     
    	}
     
    	public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		doGet(request, response);
    	}
     
    	/**
    	 * 取其某一范围的color
    	 * 
    	 * @param fc
    	 *            int 范围参数1
    	 * @param bc
    	 *            int 范围参数2
    	 * @return Color
    	 */
    	private Color getRandColor(int fc, int bc) {
    		// 取其随机颜色
    		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);
    	}
     
    }

[(页码SR1)HTTP Servlet Response设置响应头、重定向、定时刷新][SR1_HTTP Servlet Response]  
[(页码SR2)HTTP Servlet Response设置响应体、发送中文、图片][SR2_HTTP Servlet Response]  
[(页码SR3)HTTP Servlet Response文件下载基本代码][SR3_HTTP Servlet Response]  
[(页码SR4)HTTP Servlet Response一次性验证码的实现][SR4_HTTP Servlet Response]  
整合：HTTP Servlet Response完成文件下载、一次性验证码的实现

[SR1_HTTP Servlet Response]: https://blog.csdn.net/qq_40922845/article/details/104444704
[SR2_HTTP Servlet Response]: https://blog.csdn.net/qq_40922845/article/details/104448580
[SR3_HTTP Servlet Response]: https://blog.csdn.net/qq_40922845/article/details/104452337
[SR4_HTTP Servlet Response]: https://blog.csdn.net/qq_40922845/article/details/104460218