实现javaweb滑块验证码的代码
时间: 2023-10-09 15:15:28 浏览: 61
以下是一个简单的基于JavaWeb的滑块验证码实现的代码示例:
```
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.util.Config;
public class SliderCaptchaServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final int WIDTH = 200; // 滑动块验证码宽度
private static final int HEIGHT = 80; // 滑动块验证码高度
private static final int BLOCK_SIZE = 30; // 滑块边长
private static final int SHADOW_GAP = 5; // 阴影偏移量
private Producer captchaProducer;
private String captchaParamName;
public void init() throws ServletException {
captchaParamName = getConfig().getInitParameter("captchaParamName"); // 从web.xml文件中获取参数名
captchaProducer = getConfig().getProducerImpl(); // 使用kaptcha库生成滑动块验证码
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpSession session = request.getSession(false);
String sessionId = session != null ? session.getId() : "NO_SESSION"; // 获取会话的ID
String challenge = captchaProducer.createText(); // 生成验证码文本
session.setAttribute(sessionId + "." + captchaParamName, challenge); // 存储验证码文本到会话中
BufferedImage challengeImage = captchaProducer.createImage(challenge); // 生成验证码图片
int x = (int) (Math.random() * (WIDTH - BLOCK_SIZE - SHADOW_GAP * 2)) + SHADOW_GAP; // 随机生成滑块的X坐标
int y = (int) (Math.random() * (HEIGHT - BLOCK_SIZE - SHADOW_GAP * 2)) + SHADOW_GAP; // 随机生成滑块的Y坐标
BufferedImage blockImage = challengeImage.getSubimage(x, y, BLOCK_SIZE, BLOCK_SIZE); // 获取滑块图片
BufferedImage shadowImage = new BufferedImage(BLOCK_SIZE, BLOCK_SIZE, BufferedImage.TYPE_INT_ARGB); // 生成滑块阴影
for (int i = 0; i < BLOCK_SIZE; i++) {
for (int j = 0; j < BLOCK_SIZE; j++) {
int alpha = (BLOCK_SIZE - i - j) * 255 / (2 * BLOCK_SIZE); // 根据像素位置计算透明度
int rgb = (0 << 24) | (0 << 16) | (0 << 8) | 0; // 构造黑色
shadowImage.setRGB(i, j, (rgb & 0x00FFFFFF) | (alpha << 24)); // 设置像素
}
}
BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_ARGB); // 生成最终图片
image.getGraphics().drawImage(challengeImage, 0, 0, null); // 绘制验证码图片
image.getGraphics().drawImage(shadowImage, x, y, null); // 绘制滑块阴影
response.setContentType("image/png"); // 设置响应类型为PNG图片
ServletOutputStream out = response.getOutputStream();
ImageIO.write(image, "png", out); // 写出最终图片
out.flush();
out.close();
}
}
```
使用该Servlet,只需在网页端通过`<img>`标签的`src`属性访问该Servlet,即可获取一个带有滑块验证码的PNG图片。
在验证时,只需要在客户端输入滑块验证码的拼图位置(即滑块左上角在图片中的位置),并将该位置与实际位置进行比较即可。