Java实现验证码

时间：2022-02-13 16:34:45

闲言少叙，直接上代码：

1.创建一个简单的jsp，用来显示：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>Java验证码</title>
</head>

<body>
	<table width="100%" border="0" cellspacing="0" cellpadding="0">
		<tr>
			<td width="100"> </td>
			<td width="100">验证码：</td>
			<td width="150">
				<input id="veryCode" name="veryCode" type="text" class="yzm" value="" onmouseout="isRightCode()" /></td>
			<td width="135"><img id="imgObj" alt="" src="DrawImage"
				onclick="changeImg()" /></td>
			<td><a href="#" onclick="changeImg()">换一张</a></td>
			<td></td>
		</tr>
		<tr>
			<td style="line-height: 38px; color: #FF0000; text-align: center;" colspan="4" id="info"> </td>
			<td></td>
		</tr>
	</table>
	<script type="text/javascript" src="js/jQuery.js"></script>
	<script type="text/javascript" src="js/verifyCode.js"></script>
</body>
</html>
2.JavaScript代码：当然jQuary.js就直接自己找一个吧。下面是verifyCode.js 

/**
 * 验证code-js
 */

// 点击换一张验证码
function changeImg() {
	var imgSrc = $("#imgObj");
	var src = imgSrc.attr("src");
	imgSrc.attr("src", chgUrl(src));
	$("#info").html("");
}
// 时间戳
// 为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳
function chgUrl(url) {
	var timestamp = (new Date()).valueOf();
	url = url.substring(0, 17);
	if ((url.indexOf("&") >= 0)) {
		url = url + "×tamp=" + timestamp;
	} else {
		url = url + "?timestamp=" + timestamp;
	}
	return url;
}
// 验证码验证
function isRightCode() {
	var code = $("#veryCode").attr("value");
	// alert(code);
	code = "c=" + code;
	$.ajax({
		type : "POST",
		url : "ResultServlet",
		data : code,
		success : callback
	});
}
// 验证以后处理提交信息或错误信息
function callback(data) {
	if (data.toString() == 1) {
		$("#info").html("东阳提示您：验证成功了！");
		return;
	} else {
		$("#info").html(data);
		return;
	}
}
3.创建2个servlet，一个用来画图，一个用来验证结果，先来画图的DrawImage.java 

package com.wdy.yzm;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
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;

/**
 * 生成随机验证码图片
 * 
 * @author wangdy
 * 
 */
public class DrawImage extends HttpServlet {
	private static final long serialVersionUID = 1L;
	public static final int WIDTH = 120;
	public static final int HEIGHT = 30;

	// 在报java.lang.NoClassDefFoundError: Could not initialize class
	// javax.imageio.ImageIO错的时候加上这个很管用。
	static {
		ImageIO.scanForPlugins();
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		this.doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		// 创建缓存
		BufferedImage bi = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
		// 获得画布
		Graphics g = bi.getGraphics();
		// 设置背影色
		setBackGround(g);
		// 设置边框
		setBorder(g);
		// 画干扰线
		drawRandomLine(g);
		// 写随机数
		String random = drawRandomNum((Graphics2D) g);
		// 将随机汉字存在session中
		request.getSession().setAttribute("checkcode", random);
		// 将图形写给浏览器
		response.setContentType("image/jpeg");
		// 发头控制浏览器不要缓存
		response.setDateHeader("expries", -1);
		response.setHeader("Cache-Control", "no-cache");
		response.setHeader("Pragma", "no-cache");
		// 将图片写给浏览器
		ImageIO.write(bi, "jpg", response.getOutputStream());
	}

	/**
	 * 设置背景色
	 * 
	 * @param g
	 */
	private void setBackGround(Graphics g) {
		// 设置颜色
		g.setColor(new Color(249, 249, 249));
		// 填充区域
		g.fillRect(0, 0, WIDTH, HEIGHT);

	}

	/**
	 * 设置边框
	 * 
	 * @param g
	 */
	private void setBorder(Graphics g) {
		// 设置边框颜色
		// RGB
		g.setColor(new Color(210, 209, 205));
		// 边框区域
		g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
	}

	/**
	 * 画随机线条
	 * 
	 * @param g
	 */
	private void drawRandomLine(Graphics g) {
		// 设置颜色
		g.setColor(Color.GRAY);
		// 设置线条个数并画线
		for (int i = 0; i < 5; i++) {
			int x1 = new Random().nextInt(WIDTH);
			int y1 = new Random().nextInt(HEIGHT);
			int x2 = new Random().nextInt(WIDTH);
			int y2 = new Random().nextInt(HEIGHT);
			g.drawLine(x1, y1, x2, y2);
		}
	}

	/**
	 * 画随机汉字
	 * 
	 * @param g
	 * @return
	 */
	private String drawRandomNum(Graphics2D g) {
		StringBuffer sb = new StringBuffer();
		// 设置字体
		g.setFont(new Font("宋体", Font.BOLD, 20));
		// 准备常用汉字集
		// String base =
		// "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
		// String base =
		// "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
		// 准备常用字符集
		String base = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
		int x = 5;
		// 控制字数
		for (int i = 0; i < 4; i++) {
			// 生成0-255的随机数
			int R = new Random().nextInt(256);
			int G = new Random().nextInt(256);
			int B = new Random().nextInt(256);
			// 设置每个随机数的颜色
			g.setColor(new Color(R, G, B));
			// 设置字体旋转角度
			int degree = new Random().nextInt() % 30;
			// 截取汉字
			String ch = base.charAt(new Random().nextInt(base.length())) + "";
			sb.append(ch);
			// 正向角度
			g.rotate(degree * Math.PI / 180, x, 20);
			g.drawString(ch, x, 20);
			// 反向角度
			g.rotate(-degree * Math.PI / 180, x, 20);
			x += 30;
		}
		return sb.toString();
	}
}
再来用来验证结果的ResultServlet.java 

package com.wdy.yzm;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 结果验证Servlet
 * @author wangdy
 *
 */
public class ResultServlet extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doPost(request, response);
	}

	/**  
	 * 后台验证输入
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=utf-8");
		String validateC = (String) request.getSession().getAttribute("checkcode");
		//从前台传来的用户输入的验证码
		String veryCode = request.getParameter("c");
		PrintWriter out = response.getWriter();
		if (veryCode == null || "".equals(veryCode)) {
			out.println("请输入验证码！");
		} else {
//			if (validateC.equals(veryCode)) {
			//忽略大小写处理：
			if (validateC.equalsIgnoreCase(veryCode)) {
				out.println(1);
			} else {
				out.println("验证码输入错误！");
			}
		}
		out.flush();
		out.close();
	}

}
4.当然了，Servlet必须得配置在web.xml里的，如下： 

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	<servlet>
		<description>yzm</description>
		<display-name>yzm</display-name>
		<servlet-name>DrawImage</servlet-name>
		<servlet-class>com.wdy.yzm.DrawImage</servlet-class>
	</servlet>
	<servlet>
		<description>yzm</description>
		<display-name>yzm</display-name>
		<servlet-name>ResultServlet</servlet-name>
		<servlet-class>com.wdy.yzm.ResultServlet</servlet-class>
	</servlet>


	<servlet-mapping>
		<servlet-name>DrawImage</servlet-name>
		<url-pattern>/DrawImage</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>ResultServlet</servlet-name>
		<url-pattern>/ResultServlet</url-pattern>
	</servlet-mapping>
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
</web-app>
5.看结果：

Java实现验证码

以上就是所有代码和结果了。


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