图片验证码

最新推荐文章于 2024-09-06 08:16:20 发布

最新推荐文章于 2024-09-06 08:16:20 发布 · 186 阅读

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#Cache #浏览器 #Servlet

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public class ImageServlet extends HttpServlet{

	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		//设置Content-type响应头
		resp.setContentType("image/jpeg");
		
		//设置http头，不允许客户端缓存验证码图片(单个是指针对某一个浏览器生效)
		resp.setHeader("pragma", "No-cache");
		resp.setHeader("Cache-Control", "No-cache");
		resp.setDateHeader("Expires", 0);
		
		//向客户端输出二进制数据
		OutputStream out = resp.getOutputStream();
		
		//以下代码用来生成验证码图片
		int width = 80;
		int height = 20;
		BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
		Graphics g = image.getGraphics();
		g.fillRect(0, 0, width, height);
		g.setFont(new Font("Times New Roman",Font.ITALIC,18));
		
		String checkCode= "";
		Random random = new Random();
		for(int i = 0; i < 4; i++){
			String rand = String.valueOf(random.nextInt(10));
			checkCode += rand;
			//随即设置数字颜色，增加识别验证码的难度，防止识别软件盗用使用
			g.setColor(new Color(20+random.nextInt(110),
					20+random.nextInt(110),
					20+random.nextInt(110)));
			
			g.drawString(rand, i * 20 + 6, 16);
		}
		g.dispose();    //生成图片完毕
		
		//将产生的验证码存Session中
		
	    req.getSession().setAttribute("checkCode",checkCode);
	    
		ImageIO.write(image,"JPEG",out);
	}

直接调用Servlet就是....