Java Web简单的图片验证码

最新推荐文章于 2023-11-02 20:36:39 发布

粗鄙之语

最新推荐文章于 2023-11-02 20:36:39 发布

阅读量1.3k

点赞数

CC 4.0 BY-SA版权

分类专栏： Java 文章标签：验证码 servlet java web

本文链接：https://blog.youkuaiyun.com/iyeahme/article/details/43833119

Java 专栏收录该内容

2 篇文章

订阅专栏

本文介绍了一个简单的图片验证码生成类，该类能够生成包含字母和数字的验证码图片，并提供验证功能。文章提供了完整的Java代码实现，包括随机颜色生成、验证码字符串生成及图片绘制等关键步骤。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

封装了一个类，可以比较简单地生成图片验证码：

代码如下：

public class CheckCode {
	private final static String CodeMap = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
	private final static String CHECK_CODE = "CHECK_CODE";
	private final static int MapLength = 62;
	private final static int RGB = 255;
	private BufferedImage image = null;
	private Graphics graphics = null;
	private Random random = null;
	private Font font = null;
	private int width = 100;
	private int height = 30;
	private int codeLength = 4;
	private StringBuilder builder = null;

	public CheckCode() {
		init();
	}

	private void init() {
		image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
		graphics = image.getGraphics();
		random = new Random();
		font = new Font("Times New Roman", Font.BOLD, 18);
		graphics.setColor(randColor());
		graphics.fillRect(0, 0, width, height);
		builder = new StringBuilder();
		makeCode();
		graphics.dispose();
	}
<span style="white-space:pre">	</span>//生成随机颜色
	private Color randColor() {
		int r = random.nextInt(RGB);
		int g = random.nextInt(RGB);
		int b = random.nextInt(RGB);
		return new Color(r, g, b);
	}

	private String randStr() {
		int index = random.nextInt(MapLength);
		return CodeMap.charAt(index) + "";
	}

	private void makeCode() {
		graphics.setFont(font);
		for (int i = 0; i < codeLength; i++) {
			graphics.setColor(randColor());
			String str = randStr();
			builder.append(str);
			graphics.drawString(str, i * 20 + 10, 20);
		}
	}
<span style="white-space:pre">	</span>//向客户端输出验证码
	public void write(HttpServletRequest request, HttpServletResponse response) {
		request.getSession().setAttribute(CHECK_CODE, toString());
		try {
			ImageIO.write(image, "png", response.getOutputStream());
		} catch (IOException e) {
			e.printStackTrace();
			return;
		}
	}
<span style="white-space:pre">	</span>//检查请求数据中的验证码是否正确
	public static boolean check(HttpServletRequest request) {
		String tmp = request.getParameter(CHECK_CODE);
		String code = (String) request.getSession().getAttribute(CHECK_CODE);
		if (tmp == null || code == null)
			return false;
		tmp = tmp.trim().toUpperCase();
		if (code.equals(tmp))
			return true;
		return false;
	}

	@Override
	public String toString() {
		return builder.toString().toUpperCase();
	}
}

可以直接在Servlet里调用：

CheckCode checkCode=new CheckCode();
checkCode.write(request,resopnse);

还要设置ContentType

response.setContentType("image/png");

最好能禁用缓存：

  <span style="white-space:pre">		</span>response.setHeader("Pragma", "No-cache");
                response.setHeader("Cache-Control", "no-cache");
                response.setDateHeader("Expires", 0);

在html中引用Servlet地址：

<img src="Servlet路径" alt="验证码">

这个类是给一个朋友写的，比较仓促，有些地方做得不够严谨，在需要的时候可以稍作修改