加减乘除验证码(java)

加减乘除验证码(java)

(1)CaptchaUtil .java

package com.durian.common.tool;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import javax.imageio.ImageIO;

public class CaptchaUtil {

	public static String[] fuhao = { "+", "-", "*", "/" };
	public static int num = 0;

	public static String result = "";

	// 生成随机算式
	public static String random() {

		List list = new ArrayList();
		Random ran = new Random();
		int n1 = ran.nextInt(10);
		int n2 = ran.nextInt(10);
		String f = fuhao[ran.nextInt(fuhao.length)];
		StringBuilder sb = new StringBuilder(4);

		switch (f) {
		case "+":
			num = n1 + n2;
			break;
		case "-":
			num = n1 - n2;
			break;
		case "*":
			num = n1 * n2;
			break;
		case "/":
			if (n2 == 0) {
				n2 = ran.nextInt(10) + 1;
				num = n1 / n2;
			} else {
				num = n1 / n2;
			}
			break;
		}
		sb.append(n1);
		sb.append(f);
		sb.append(n2);
		sb.append("=");

		result = num + "";
		return sb.toString();
	}

	public static void outputImage(String str, OutputStream os) {
		Random ran = new Random();
		// 创建图片对象
		BufferedImage img = new BufferedImage(100, 40, BufferedImage.TYPE_INT_RGB);
		// 获取画布
		Graphics g = img.getGraphics();
		// 设置背景
		g.setColor(Color.white);
		g.fillRect(0, 0, 100, 40);
		// 写字
		g.setColor(Color.black);
		g.setFont(new Font("微软雅黑", Font.PLAIN, 30));
		g.drawString(str, 10, 40);
		// 随机三条线
		g.drawLine(ran.nextInt(100), ran.nextInt(40), ran.nextInt(100), ran.nextInt(40));
		g.drawLine(ran.nextInt(100), ran.nextInt(40), ran.nextInt(100), ran.nextInt(40));
		g.drawLine(ran.nextInt(100), ran.nextInt(40), ran.nextInt(100), ran.nextInt(40));
		// 4. 输出结果
		// 常见的压缩格式：jpeg(有损压缩), png(无损压缩) ...
		try {
			ImageIO.write(img, "png", os);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

（2）CaptchaServlet.java

package com.durian.amanager.servlet;

import java.io.IOException;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.durian.amanager.constant.XConstant;
import com.durian.common.entity.Captcha;
import com.durian.common.tool.CaptchaUtil;
import com.durian.common.tool.IPUtil;

/**
 * 获取验证码
 * 
 * @author leng
 *
 */
@WebServlet(urlPatterns = "/captcha.png")
public class CaptchaServlet extends HttpServlet {

	private static final Logger logger = LoggerFactory.getLogger(CaptchaServlet.class);

	@Override
	protected void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("image/png");
		// 获取随机字符串
		String random = CaptchaUtil.random();
		Captcha captcha = Captcha.build(random, CaptchaUtil.result, new Date());
		HttpSession session = request.getSession();
		String sessionId = session.getId();
		String clientIp = IPUtil.getIpAddr(request);

		// 存入结果
		session.setAttribute(XConstant.CAPTCHA, captcha.getResult());

		// 输出图片
		CaptchaUtil.outputImage(random, response.getOutputStream());

		logger.info("获取验证码,客户端IP=" + clientIp + ",sessionId=" + sessionId + ",验证码信息:" + captcha.toJsonObjectString());
	}
}

(3)Captcha.java

package com.durian.common.entity;

import java.io.Serializable;
import java.util.Date;

import com.alibaba.fastjson.JSONObject;

/**
 * 验证码实体
 * 
 * @author leng
 *
 */
public class Captcha implements Serializable {

	/**
	 * 验证码
	 */
	private String captcha;

	/**
	 * 结果
	 */
	private String result;

	/**
	 * 创建时间
	 */
	private Date createTime;

	/**
	 * 超时时间(秒)(默认30分钟)
	 */
	private int timeout = 30_000;

	/**
	 * 构建验证码
	 * 
	 * @param captcha    显示内容
	 * @param result     验证码结果
	 * @param createTime 创建时间
	 * @return
	 */
	public static Captcha build(String captcha, String result, Date createTime) {
		Captcha cap = new Captcha();
		cap.setCaptcha(captcha);
		cap.setResult(result);
		cap.setCreateTime(createTime);
		return cap;
	}

	public String getCaptcha() {
		return captcha;
	}

	public void setCaptcha(String captcha) {
		this.captcha = captcha;
	}

	public String getResult() {
		return result;
	}

	public void setResult(String result) {
		this.result = result;
	}

	public Date getCreateTime() {
		return createTime;
	}

	public void setCreateTime(Date createTime) {
		this.createTime = createTime;
	}

	public int getTimeout() {
		return timeout;
	}

	public void setTimeout(int timeout) {
		this.timeout = timeout;
	}

	public String toJsonObjectString() {
		return JSONObject.toJSONString(this);
	}

}

(4)使用：

<img src="../captcha.png" id="captcha_form_reg" οnclick="this.src ='../captcha.png?t='+new Date().getTime()" />